Eight Pitfalls in Evaluating Green Energy Solutions

4 07 2016

Does the recent climate accord between US and China mean that many countries will now forge ahead with renewables and other green solutions? I think that there are more pitfalls than many realize.

Pitfall 1. Green solutions tend to push us from one set of resources that are a problem today (fossil fuels) to other resources that are likely to be problems in the longer term.  

The name of the game is “kicking the can down the road a little.” In a finite world, we are reaching many limits besides fossil fuels:

  1. Soil quality–erosion of topsoil, depleted minerals, added salt
  2. Fresh water–depletion of aquifers that only replenish over thousands of years
  3. Deforestation–cutting down trees faster than they regrow
  4. Ore quality–depletion of high quality ores, leaving us with low quality ores
  5. Extinction of other species–as we build more structures and disturb more land, we remove habitat that other species use, or pollute it
  6. Pollution–many types: CO2, heavy metals, noise, smog, fine particles, radiation, etc.
  7. Arable land per person, as population continues to rise

The danger in almost every “solution” is that we simply transfer our problems from one area to another. Growing corn for ethanol can be a problem for soil quality (erosion of topsoil), fresh water (using water from aquifers in Nebraska, Colorado). If farmers switch to no-till farming to prevent the erosion issue, then great amounts of Round Up are often used, leading to loss of lives of other species.

Encouraging use of forest products because they are renewable can lead to loss of forest cover, as more trees are made into wood chips. There can even be a roundabout reason for loss of forest cover: if high-cost renewables indirectly make citizens poorer, citizens may save money on fuel by illegally cutting down trees.

High tech goods tend to use considerable quantities of rare minerals, many of which are quite polluting if they are released into the environment where we work or live. This is a problem both for extraction and for long-term disposal.

Pitfall 2. Green solutions that use rare minerals are likely not very scalable because of quantity limits and low recycling rates.  

Computers, which are the heart of many high-tech goods, use almost the entire periodic table of elements.

Figure 1. Slide by Alicia Valero showing that almost the entire periodic table of elements is used for computers.

When minerals are used in small quantities, especially when they are used in conjunction with many other minerals, they become virtually impossible to recycle. Experience indicates that less than 1% of specialty metals are recycled.

Figure 2. Slide by Alicia Valero showing recycling rates of elements.

Green technologies, including solar panels, wind turbines, and batteries, have pushed resource use toward minerals that were little exploited in the past. If we try to ramp up usage, current mines are likely to deplete rapidly. We will eventually need to add new mines in areas where resource quality is lower and concern about pollution is higher. Costs will be much higher in such mines, making devices using such minerals less affordable, rather than more affordable, in the long run.

Of course, a second issue in the scalability of these resources has to do with limits on oil supply. As ores of scarce minerals deplete, more rather than less oil will be needed for extraction. If oil is in short supply, obtaining this oil is also likely to be a problem, also inhibiting scalability of the scarce mineral extraction. The issue with respect to oil supply may not be high price; it may be low price, for reasons I will explain later in this post.

Pitfall 3. High-cost energy sources are the opposite of the “gift that keeps on giving.” Instead, they often represent the “subsidy that keeps on taking.”

Oil that was cheap to extract (say $20 barrel) was the true “gift that keeps on giving.” It made workers more efficient in their jobs, thereby contributing to efficiency gains. It made countries using the oil more able to create goods and services cheaply, thus helping them compete better against other countries. Wages tended to rise, as long at the price of oil stayed below $40 or $50 per barrel (Figure 3).

Figure 3. Average wages in 2012$ compared to Brent oil price, also in 2012$. Average wages are total wages based on BEA data adjusted by the CPI-Urban, divided total population. Thus, they reflect changes in the proportion of population employed as well as wage levels.

More workers joined the work force, as well. This was possible in part because fossil fuels made contraceptives available, reducing family size. Fossil fuels also made tools such as dishwashers, clothes washers, and clothes dryers available, reducing the hours needed in housework. Once oil became high-priced (that is, over $40 or $50 per barrel), its favorable impact on wage growth disappeared.

When we attempt to add new higher-cost sources of energy, whether they are high-cost oil or high-cost renewables, they present a drag on the economy for three reasons:

  1. Consumers tend to cut back on discretionary expenditures, because energy products (including food, which is made using oil and other energy products) are a necessity. These cutbacks feed back through the economy and lead to layoffs in discretionary sectors. If they are severe enough, they can lead to debt defaults as well, because laid-off workers have difficulty paying their bills.
  2.  An economy with high-priced sources of energy becomes less competitive in the world economy, competing with countries using less expensive sources of fuel. This tends to lead to lower employment in countries whose mix of energy is weighted toward high-priced fuels.
  3. With (1) and (2) happening, economic growth slows. There are fewer jobs and debt becomes harder to repay.

In some sense, the cost producing of an energy product is a measure of diminishing returns–that is, cost is a measure of the amount of resources that directly and indirectly or indirectly go into making that device or energy product, with higher cost reflecting increasing effort required to make an energy product. If more resources are used in producing high-cost energy products, fewer resources are available for the rest of the economy. Even if a country tries to hide this situation behind a subsidy, the problem comes back to bite the country. This issue underlies the reason that subsidies tend to “keeping on taking.”

The dollar amount of subsidies is also concerning. Currently, subsidies for renewables (before the multiplier effect) average at least $48 per barrel equivalent of oil.1 With the multiplier effect, the dollar amount of subsidies is likely more than the current cost of oil (about $80), and possibly even more than the peak cost of oil in 2008 (about $147). The subsidy (before multiplier effect) per metric ton of oil equivalent amounts to $351. This is far more than the charge for any carbon tax.

Pitfall 4. Green technology (including renewables) can only be add-ons to the fossil fuel system.

A major reason why green technology can only be add-ons to the fossil fuel system relates to Pitfalls 1 through 3. New devices, such as wind turbines, solar PV, and electric cars aren’t very scalable because of high required subsidies, depletion issues, pollution issues, and other limits that we don’t often think about.

A related reason is the fact that even if an energy product is “renewable,” it needs long-term maintenance. For example, a wind turbine needs replacement parts from around the world. These are not available without fossil fuels. Any electrical transmission system transporting wind or solar energy will need frequent repairs, also requiring fossil fuels, usually oil (for building roads and for operating repair trucks and helicopters).

Given the problems with scalability, there is no way that all current uses of fossil fuels can all be converted to run on renewables. According to BP data, in 2013 renewable energy (including biofuels and hydroelectric) amounted to only 9.4% of total energy use. Wind amounted to 1.1% of world energy use; solar amounted to 0.2% of world energy use.

Pitfall 5. We can’t expect oil prices to keep rising because of affordability issues.  

Economists tell us that if there are inadequate oil supplies there should be few problems:  higher prices will reduce demand, encourage more oil production, and encourage production of alternatives. Unfortunately, there is also a roundabout way that demand is reduced: wages tend to be affected by high oil prices, because high-priced oil tends to lead to less employment (Figure 3). With wages not rising much, the rate of growth of debt also tends to slow. The result is that products that use oil (such as cars) are less affordable, leading to less demand for oil. This seems to be the issue we are now encountering, with many young people unable to find good-paying jobs.

If oil prices decline, rather than rise, this creates a problem for renewables and other green alternatives, because needed subsidies are likely to rise rather than disappear.

The other issue with falling oil prices is that oil prices quickly become too low for producers. Producers cut back on new development, leading to a decrease in oil supply in a year or two. Renewables and the electric grid need oil for maintenance, so are likely to be affected as well. Related posts include Low Oil Prices: Sign of a Debt Bubble Collapse, Leading to the End of Oil Supply? and Oil Price Slide – No Good Way Out.

Pitfall 6. It is often difficult to get the finances for an electrical system that uses intermittent renewables to work out well.  

Intermittent renewables, such as electricity from wind, solar PV, and wave energy, tend to work acceptably well, in certain specialized cases:

  • When there is a lot of hydroelectricity nearby to offset shifts in intermittent renewable supply;
  • When the amount added is sufficient small that it has only a small impact on the grid;
  • When the cost of electricity from otherwise available sources, such as burning oil, is very high. This often happens on tropical islands. In such cases, the economy has already adjusted to very high-priced electricity.

Intermittent renewables can also work well supporting tasks that can be intermittent. For example, solar panels can work well for pumping water and for desalination, especially if the alternative is using diesel for fuel.

Where intermittent renewables tend not to work well is when

  1. Consumers and businesses expect to get a big credit for using electricity from intermittent renewables, but
  2. Electricity added to the grid by intermittent renewables leads to little cost savings for electricity providers.

For example, people with solar panels often expect “net metering,” a credit equal to the retail price of electricity for electricity sold to the electric grid. The benefit to electric grid is generally a lot less than the credit for net metering, because the utility still needs to maintain the transmission lines and do many of the functions that it did in the past, such as send out bills. In theory, the utility still should get paid for all of these functions, but doesn’t. Net metering gives way too much credit to those with solar panels, relative to the savings to the electric companies. This approach runs the risk of starving fossil fuel, nuclear, and grid portion of the system of needed revenue.

A similar problem can occur if an electric grid buys wind or solar energy on a preferential basis from commercial providers at wholesale rates in effect for that time of day. This practice tends to lead to a loss of profitability for fossil fuel-based providers of electricity. This is especially the case for natural gas “peaking plants” that normally operate for only a few hours a year, when electricity rates are very high.

Germany has been adding wind and solar, in an attempt to offset reductions in nuclear power production. Germany is now running into difficulty with its pricing approach for renewables. Some of its natural gas providers of electricity have threatened to shut down because they are not making adequate profits with the current pricing plan. Germany also finds itself using more cheap (but polluting) lignite coal, in an attempt to keep total electrical costs within a range customers can afford.

Pitfall 7. Adding intermittent renewables to the electric grid makes the operation of the grid more complex and more difficult to manage. We run the risk of more blackouts and eventual failure of the grid. 

In theory, we can change the electric grid in many ways at once. We can add intermittent renewables, “smart grids,” and “smart appliances” that turn on and off, depending on the needs of the electric grid. We can add the charging of electric automobiles as well. All of these changes add to the complexity of the system. They also increase the vulnerability of the system to hackers.

The usual assumption is that we can step up to the challenge–we can handle this increased complexity. A recent report by The Institution of Engineering and Technology in the UK on the Resilience of the Electricity Infrastructure questions whether this is the case. It says such changes, ” .  .  . vastly increase complexity and require a level of engineering coordination and integration that the current industry structure and market regime does not provide.” Perhaps the system can be changed so that more attention is focused on resilience, but incentives need to be changed to make resilience (and not profit) a top priority. It is doubtful this will happen.

The electric grid has been called the worlds ‘s largest and most complex machine. We “mess with it” at our own risk. Nafeez Ahmed recently published an article called The Coming Blackout Epidemic, discussing challenges grids are now facing. I have written about electric grid problems in the past myself: The US Electric Grid: Will it be Our Undoing?

Pitfall 8. A person needs to be very careful in looking at studies that claim to show favorable performance for intermittent renewables.  

Analysts often overestimate the benefits of wind and solar. Just this week a new report was published saying that the largest solar plant in the world is so far producing only half of the electricity originally anticipated since it opened in February 2014.

In my view, “standard” Energy Returned on Energy Invested (EROEI) and Life Cycle Analysis (LCA) calculations tend to overstate the benefits of intermittent renewables, because they do not include a “time variable,” and because they do not consider the effect of intermittency. More specialized studies that do include these variables show very concerning results. For example, Graham Palmer looks at the dynamic EROEI of solar PV, using batteries (replaced at eight year intervals) to mitigate intermittency.2 He did not include inverters–something that would be needed and would reduce the return further.

Figure 4. Graham Palmer's chart of Dynamic Energy Returned on Energy Invested from "Energy in Australia."

Palmer’s work indicates that because of the big energy investment initially required, the system is left in a deficit energy position for a very long time. The energy that is put into the system is not paid back until 25 years after the system is set up. After the full 30-year lifetime of the solar panel, the system returns 1.3 times the initial direct energy investment.

One further catch is that the energy used in the EROEI calculations includes only a list of direct energy inputs. The total energy required is much higher; it includes indirect inputs that are not directly measured as well as energy needed to provide necessary infrastructure, such as roads and schools. When these are considered, the minimum EROEI needs to be something like 10. Thus, the solar panel plus battery system modeled is really a net energy sink, rather than a net energy producer.  

Another study by Weissbach et al. looks at the impact of adjusting for intermittency. (This study, unlike Palmer’s, doesn’t attempt to adjust for timing differences.) It concludes, “The results show that nuclear, hydro, coal, and natural gas power systems . . . are one order of magnitude more effective than photovoltaics and wind power.”

Conclusion

It would be nice to have a way around limits in a finite world. Unfortunately, this is not possible in the long run. At best, green solutions can help us avoid limits for a little while longer.

The problem we have is that statements about green energy are often overly optimistic. Cost comparisons are often just plain wrong–for example, the supposed near grid parity of solar panels is an “apples to oranges” comparison. An electric utility cannot possibility credit a user with the full retail cost of electricity for the intermittent period it is available, without going broke. Similarly, it is easy to overpay for wind energy, if payments are made based on time-of-day wholesale electricity costs. We will continue to need our fossil-fueled balancing system for the electric grid indefinitely, so we need to continue to financially support this system.

There clearly are some green solutions that will work, at least until the resources needed to produce these solutions are exhausted or other limits are reached. For example, geothermal may be solutions in some locations. Hydroelectric, including “run of the stream” hydro, may be a solution in some locations. In all cases, a clear look at trade-offs needs to be done in advance. New devices, such as gravity powered lamps and solar thermal water heaters, may be helpful especially if they do not use resources in short supply and are not likely to cause pollution problems in the long run.

Expectations for wind and solar PV need to be reduced. Solar PV and offshore wind are both likely net energy sinks because of storage and balancing needs, if they are added to the electric grid in more than very small amounts. Onshore wind is less bad, but it needs to be evaluated closely in each particular location. The need for large subsidies should be a red flag that costs are likely to be high, both short and long term. Another consideration is that wind is likely to have a short lifespan if oil supplies are interrupted, because of its frequent need for replacement parts from around the world.

Some citizens who are concerned about the long-term viability of the electric grid will no doubt want to purchase their own solar systems with inverters and back-up batteries. I see no reason to discourage people who want to do this–the systems may prove to be of assistance to these citizens. But I see no reason to subsidize these purchases, except perhaps in areas (such as tropical islands) where this is the most cost-effective way of producing electric power.

Notes:

[1] In 2013, the total amount of subsidies for renewables was $121 billion according to the IEA. If we compare this to the amount of renewables (biofuels + other renewables) reported by BP, we find that the subsidy per barrel of oil equivalent in was $48 per barrel of oil equivalent. These amounts are likely understated, because BP biofuels include fuel that doesn’t require subsidies, such as waste sawdust burned for electricity.

[2] Palmer’s work is published in Energy in Australia: Peak Oil, Solar Power, and Asia’s Economic Growth, published by Springer in 2014. This book is part of Prof. Charles Hall’s “Briefs in Energy” series.





Another sublime article on ERoEI

26 05 2016

ERoEI for Beginners

Not sure if I can come to terms with the concept of kite flying with wind turbines, but there you go……  doesn’t make renewables look good, that’s for sure.  Reblogged from Euan’s excellent website…..

The Energy Return on Energy Invested (ERoEI or EROI) of any energy gathering system is a measure of that system’s efficiency. The concept was originally derived in ecology and has been transferred to analyse human industrial society. In today’s energy mix, hydroelectric power ± nuclear power have values > 50. At the other end of the scale, solar PV and biofuels have values <5.

It is assumed that ERoEI >5 to 7 is required for modern society to function. This marks the edge of The Net Energy Cliff and it is clear that new Green technologies designed to save humanity from CO2 may kill humanity through energy starvation instead. Fossil fuels remain comfortably away from the cliff edge but march closer to it for every year that passes. The Cheetah symbolises an energy system living on the edge.

I first came across the concept of Energy Return on Energy Invested (ERoEI) several years ago in Richard Heinberg’s book The Party’s Over [1]. I had never contemplated the concept before and I was immediately struck by its importance. If we used more energy to get the energy we need to survive then we will surely perish.

Shortly thereafter I joined The Oil Drum crew and had the great pleasure of meeting Professor Charles Hall,  the Godfather of ERoEI analysis who developed the concept during his PhD studies and first published the term in 1977. ERoEI would become a point of focus for Oil Drum posts. Nate Hagens and David Murphy, both Oil Drum crew, have now completed PhDs on ERoEI analysis aided and abetted by the conversation that the Oil Drum enabled.

But recently I have received this via email from Nate:

10 years on the same questions and issues are being addressed – (and maybe 40 years on for Charlie). A new tier of people are aware of EROI but it is still very fringe idea?

Are we wrong to believe that ERoEI is a fundamentally important metric of energy acquisition or is it simply that the work done to date is not sufficiently rigorous or presented in a way that economists and policy makers can understand. At this point I will cast out a bold idea that money was invented as a proxy for energy because ERoEI was too complex to fathom.

And I have this via email from my friend Luis de Sousa who did not like the Ferroni and Hopkirk paper [3] nor my post reviewing it:

On the grand scheme of things: PV ERoEI estimates range from 30 down to 0.8. Before asking the IEA (or whomever) to start using ERoEI, the community producing these estimates must come down to a common, accepted methodology for its assessment. As it stands now, EROEI is not far from useless to energy policy.

And while I disagree with Luis on a number of issues, on this statement I totally concur. So what has gone wrong? Professor Hall points out that it is not the concept that is at fault but non-rigorous application of certain rules that must be followed in the analysis. In this post I will endeavour to review the main issues and uncertainties, and while it is labelled “for Beginners”, I will flirt with an intermediate level of complexity.

What is ERoEI?

ERoEI is simply the ratio of energy gathered to the amount of energy used to gather the energy (the energy invested):

ERoEI = energy gathered / energy invested

Note that in common vernacular the term energy production is used. But in fact humans produce very little energy, but what distinguishes us from other species is that we have become very efficient at gathering energy that already exists and building machines that can convert the energy to goods (motor cars, televisions and computers) and services (heat and light and mobility) that collectively define our wealth.

This began by gathering fire wood and food and progressed to gathering coal, oil and natural gas. This led to gathering U and Th and learning how to convert this to enormous amounts of thermal and electrical energy. And now we attempt to gather solar energy through photovoltaics, wind turbines and liquid biofuels.

The prosperity of humanity depends upon the efficiency with which we gather energy. 100 years ago and 50 years ago we hit several jackpots in the form of vast coal, oil and gas deposits. These were so rich and large that energy virtually spewed out of them for next to no energy or financial investment. Examples include the Black Thunder coal field (USA), the Ghawar oil field (Saudi Arabia) and the Urengoy gas field (Russia) to name but a few. But these supergiant deposits are now to varying degrees used up. And as global population has grown together with expectations of prosperity that are founded on energy gathering activities, humanity has had to expand its energy gathering horizons to nuclear power, solar power and energy from waste. And it is known that some of the strategies deployed have very low ERoEI, for example corn ethanol is around 1 to 2 [2] and solar PV between 1 and 5 [2,3] depending upon where it is sited and the boundaries used to estimate energy costs. Consider that an ERoEI greater than 5 to 7 is deemed necessary to sustain the society we know (see below) then it is apparent that we may be committing energy and economic suicide by deliberately moving away from fossil fuels.

Low ERoEI is expected to correlate with high cost and in the normal run of events investors should steer clear of such poor investment returns. But the global energy system is now dictated by climate concern, and any scheme that portends to produce energy with no CO2 is embraced by policymakers everywhere and financial arrangements are put in place to enable deployment, regardless of the ERoEI.

Net Energy

Net energy is the close cousin of ERoEI being the surplus energy made available to society from our energy gathering activities. It is defined simply as:

net energy = ERoEI-1

If we have ERoEI = 1, then the net energy is zero. We use as much energy to gather energy as energy gathered. The “1” always represents the energy invested. If ERoEI falls below 1 we end up with an energy sink. Low ERoEI systems are effectively energy conversions where it may be convenient or politically expedient for us to convert one energy carrier into another with little or no energy gain. Corn ethanol is a good example where fertiliser, natural gas, diesel, electricity, land, water and labour gets converted into ethanol, a liquid fuel that can go in our cars. But it does leave the question why we don’t just use liquefied natural gas as a transport fuel in the first place and save on all the bother that creating corn ethanol involves?

The Net Energy Cliff

Many years ago during a late night blogging session on The Oil Drum, and following a post by Nate Hagens, I came up with a way of plotting ERoEI that for many provided an instantaneous understanding of its importance. The graph has become known as the net energy cliff, following nomenclature of Nate and others.

Figure 1 The Net Energy Cliff shows how with declining ERoEI society must commit ever larger amounts of available energy to energy gathering activities. Below ERoEI = 5 to 7 such large numbers of people would be working for the energy industries that there would not be enough people left to fill all the other positions our current altruistic society offers.

The graph plots net energy as a % of ERoEI and shows how energy for society (in blue) varies with ERoEI. In red is the balance being the energy used to gather energy.

It is the shape of the boundary between blue and red that is of interest. If we start at 50 and work our way down the ERoEI scale moving to the right, we see that energy invested (red) increases very slowly from 2% at ERoEI=50 to 10% at ERoEI=10. But beyond 10, the energy invested increases exponentially to 20% at ERoEI=5 and to 50% at ERoEI=2. At ERoEI = 1, 100% of the energy used is spent gathering energy and we are left with zero gain.

This is important because it is the blue segment that is available for society to use. This pays for infrastructure, capital projects, mining and manufacturing, agriculture, food processing and retailing, education, healthcare and welfare, defence and government. In fact it is the amount of net energy that powers everything in society as we know it today. The net energy from past energy gathering has accumulated to create what we identify as capital and wealth. Nothing could be more important, and yet the concept remains on the fringe of energy policy and public awareness. One of the problems is that measuring ERoEI consistently is difficult to do. One problem is retaining objectivity. If you manufacture PV modules you are unlikely to claim that the ERoEI is less than 5, and there are a multitude of variables that can be adjusted to provide whatever answer is deemed to be good.

This depiction of Net Energy is also useful in defining that all energy and labour can be divided into energy and labour used in the energy industries and the industries that support them and energy and labour used by society that consumes the surpluses produced by the energy industries. More on this later.

It has been assumed by many that ERoEI > 7 was required for the industrial society we live in to function although the source of this assertion remains elusive. But the blue-red boundary provides a clear visual picture of why this may be so. Below 7 and humanity falls off the net energy cliff where a too large portion of our human resources and capital need to be invested in simply staying alive to the detriment of the services provided by net energy such as health care, education and pensions.

System boundaries

Energy Inputs

One of the main uncertainties in ERoEI analysis is where to set the system boundaries. I have not found a simple text or graphic that adequately explains this vital concept.

Figure 2 A simplified scheme for an energy system divided into construction, operation and decommissioning with accumulated inputs and outputs. Graphic from this excellent presentation by Prieto and Hall

Figure 2 provides an illustration of the life cycle of an energy system divided into three stages 1) construction, 2) operation and 3) decommissioning. Energy inputs occur at each stage but energy outputs will normally only occur during the operational phase. It should be straight forward to account for all the energy inputs and outputs to calculate ERoEI but it isn’t. For example many / most of our energy systems today are still operational. We do not yet have final numbers for oil produced from single fields. And the decommissioning energy costs are not yet known. Most wind turbines ever built are still operational, producing energy and the ultimate energy produced will depend upon how long they last. And then perhaps some turbines are offered a new lease of life via refurbishment etc.

Energy inputs can normally be divided as follows [2]:

  1. On site energy consumption
  2. Energy embedded in materials used
  3. Energy consumed by labour
  4. Auxiliary services

Moving from 1 to 4 may be considered expansion of the ERoEI boundary where energy embedded in materials and energy consumed by labour are added to on-site energy consumption. There follows some examples of ambiguity that remains in deciding what to include and what to leave out. These examples are given for purely illustrative purposes.

No one should question that the electricity used by a PV factory should be included. But do you include electricity / energy used to heat or cool the factory? Or just the electricity used to run the machines? Including heating or cooling  introduces a site specific variable which will mean that the energy inputs to a PV panel may vary according to where it was manufactured. There are many such site specific variables like transport, energy costs, labour energy costs, health and safety energy costs etc, which when combined in our globalised market has made China the lowest energy cost centre for PV manufacturing today.

It is clear to me that the energy cost of all materials used in the energy production process must be included. And this should include materials consumed at the construction, operational and decommissioning stages. In the oil industry this will include the materials in the oil platform, the helicopter and the onshore office. In the solar PV industry this will include all the materials in the panels, in the factory, and in the support gantries and inverter. As a general rule of thumb, massive energy gathering systems that contain a huge amount of materials will have reduced ERoEI because of the energy embedded in those materials.

It is also clear to me that the energy cost of all labour should be included in the ERoEI analysis for construction, operation and decommissioning. But it is far less clear how it should be calculated. The energy consumed by labourers varies greatly from country to country and with time. Should we just include the energy consumed by a labourer on his/her 8 hour shift? Or should we include the full 24/7? Should the energy consumed by labourers getting to and from work be included? – of course it should. Should the energy consumed on vacations be included? – not so clear. And how can any of this be calculated in the first place?

The standard way to calculate the energy cost of labour is to examine the energy intensity of GDP. For most countries, the total amount of primary energy consumed  is roughly known and the total GDP is known. This provides a means of converting MJ to $ and we can then look at the $ earnings of a labourer to get a rough handle on the notional energy use that may be attributed to his salary scale. This is far from perfect but is currently the only practical method available.

Auxiliary services become even more difficult to differentiate. Some argue that the energy cost of the highway network, power distribution network and services like schools and hospitals should be pro-rated into new energy production systems. My own preference is to generally exclude these items from an ERoEI analysis unless there are good reasons for not doing so. I think it is useful to go back to the question are we expending energy on energy gathering or are we expending energy on society and most of the infrastructure upon which new energy systems depend was built using prior surpluses allocated to society. In my view it becomes too complex to pro-rate these into an ERoEI calculation. The power grid delivering power to the PV factory already existed. But if a new power line needs to be built to export renewable electricity then that should be accounted for.

Energy Outputs

One might imagine that measuring the energy output would be more straightforward, but it is not so. Many earlier studies on the ERoEI of oil set a boundary at the well head or on site tank farm. And it is relatively straightforward to measure the oil production from a field like Forties in the North Sea. But crude oil itself is rarely used directly as a fuel. It is the refined products that are used. To actually use the oil we need to ship or pipe it to shore and then on to a refinery. The energy cost of transport may add 10% to energy inputs and refining may add yet another 10%. It has been suggested that one approach is to calculate ERoEI at Point of Use. Crude oil on an offshore platform is of no use to anyone. Gasoline in a filling station is what we want and all the energy inputs involved in getting the gasoline to the forecourt need to be counted.

But here we meet another dilemma. The refinery may produce paraffin and gasoline. The ERoEI of both are likely to be similar at the refinery gate. But the gasoline is burned in an engine to produce kinetic energy used for transport and in so doing about 70% of the energy is lost as waste heat. The paraffin may be burned in a stove with near 100% conversion efficiency to space heating. Do we reduce the ERoEI of gasoline by 70% to reflect energy losses during use?

This introduces the concept of energy quality where we know that final energy conversions are in three main forms 1) heat 2) motion and 3) electricity that has a myriad of different uses. Is it really possible to compare these very different energy outputs using the single umbrella of ERoEI? The routine followed by ERoEI analysts to date is to adjust ERoEI for energy quality though I’m unsure how that is done [2]. Another option that I like is to hypothetically normalise all outputs to a single datum, for example MWh of electricity (see below). But this again gets to a level of complexity that is beyond this blog post.

There are some other important energy quality factors. Dispatch for electricity is one. Producing a vast amount of electricity from wind on a stormy Sunday night has little to no value. While the ability to produce electricity on demand at 6 pm on a freezing Wednesday evening in January (NH) is of great value. Curtailed wind should clearly be deducted from wind energy produced in the ERoEI calculation. Just like the oil spilled from the Deep Water Horizon in the Gulf of Mexico should not be counted as oil produced from the Macondo field.

External environmental factors may also have to be considered as part of the energy quality assessment. It is clear that the oil spilled from the Deep Water Horizon had to be cleared up immediately and the energy cost of doing so almost bankrupted BP. But it is less clear that the energy cost of eliminating CO2 emissions needs to be borne by the energy production industries. For example, the cost of carbon capture and storage would fall on the consumer and not the energy producer.

Using energy proxies

In ERoEI analysis direct energy use can normally be measured, for example gas and diesel used on an oil platform or the electricity used in a factory. But the indirect energy consumed by, for example materials and labour, are less easy to measure and are often based on proxies.  It is nearly impossible to measure the energy embedded in an offshore oil platform. Instead the mass of steel and the number of man days of labour used in construction can be estimated and from these the energy expended and now embedded in the platform can be estimated.

As already discussed, the standard way of estimating the energy cost of labour is to use the energy intensity of GDP data from the countries in question combined with workers salaries.

For materials Murphy et al [2] provide this useful summary (Figure 3)

Figure 3 The estimated energy content of common materials [2]

From this the most striking feature is the vast range within certain materials and between materials. For example aluminium ranges from 100 to 272 GJ/tonne. Steel 9 to 32 GJ/tonne. Part of this will be down to methodological differences in the way the numbers are derived. But part of it may be down to real differences reflecting different energy efficiencies of smelting plants.

ERoEI of Global Fuels and Energy Flows

So what is the current status of ERoEI in the global energy mix? Hall et al 2014 [4] provide the following summary table which is the foundation of the summary graph below.

Figure 4 Summary of the ERoEI for a range of fuels and renewable energies.

Figure 5 Placing main energy sources on The Net Energy Cliff framework shows that hydro-electric power, high altitude kites and perhaps nuclear power have very high ERoEI and embracing these technologies may prevent humanity from falling off the Net Energy Cliff. The new bright Green energies of bio-fuels, solar PV and buffered wind (see below) are already over the cliff edge and if we continue to embrace these technologies human society may perish as we expend too large a portion of our energy endowment simply getting energy. Fossil fuels remain comfortably to the left of the cliff edge but are marching ever closer towards it with every year that passes. Eeq = electricity equivalent (see below).

In order to compare fossil fuels with electricity flows on a single diagram it is essential to reduce all of the energy types to a common datum. Its quite simply not valid to compare the ERoEI of coal at the mine mouth with nuclear power since in converting the coal to electricity, much of the energy is lost. The easiest route is to rebase everything to electricity equivalent (Eeq) where I follow the BP convention and adjust the ERoEI of  fossil fuels by a factor of 0.38 to account for energy conversion losses in a modern power station.

In an earlier thread, Owen posted a link to a pre-print by Weisbach et al [5] who follow similar methodology reporting all data as electricity. To a large extent their numbers are similar to those reported here with the exception of nuclear that is quoted to be  75. Weisbach report values for solar PV and wind that are “buffered” to include the energy cost of intermittency. This reduces the ERoEI for solar PV by about half and wind by a factor of 4. “Buffered” ERoEIs are therefore also included in Figure 6.

The inclusion of high altitude kite is based on a calculation provided by site sponsor KiteGen. I have checked the calculation and am satisfied that the ERoEI is potentially >>50. This will be the subject of another post. But suffice to say here that wind speed at altitude may be double that on the ground and power increases by the cube of wind speed. And the mass of the KiteGen structure is a small fraction of a large wind turbine. Hence it is theoretically straightforward to reach an ERoEI at altitude that is many multiples of the ERoEI of a wind turbine.

Figure 6 At altitude the wind speed may be double that on the ground. Accessing that kinetic energy resource provides potential for a 2 to 4 fold uplift in the power available for wind generation. This calculation does not include further uplift from higher capacity factor and reduced intermittency at altitude.

The key and fundamental observation from Figure 6 is that three energy sources potentially have ERoEI >> 50 making them vastly superior to all others using this metric. These are hydroelectric power, possibly nuclear power (depending upon whose numbers are believed) and possibly high altitude wind power once the technology matures.

These primary high ERoEI sources are followed by coal and natural gas which are the most viable and easily accessible energy sources for electricity today. And yet energy policies are dictating that coal be phased out. This will not matter for so long as natural gas remains plentiful at high ERoEI. The high ERoEI group may also include nuclear power depending upon whose ERoEI numbers one believes.

Biofuels are already over the net energy cliff and should never have been pursued in the first place. Solar PV is at best marginal, at worst an energy sink.

There is a vast range in estimates for nuclear power from 5 to 75 [4, 5]and it is difficult to make sense of these numbers. Nuclear power either sits close to the cliff edge or is a high ERoEI low carbon saviour of humanity. Oil will not be used for electricity production and the fact it sits close to the cliff edge today in Eeq form does not matter too much since the energy quality of oil has a special status as an essential transport fuel and this will unlikely change much in the decades ahead.

Concluding thoughts

The concept of ERoEI is vital to understanding the human energy system. 50 years ago, our principal sources of energy – oil, gas and coal – had such high net energy return that no one need bother or worry about ERoEI. Vast amounts of net energy were simply available for all who had the level of technological development to build a power station and a transmission grid. It is part of human nature to “high grade” mineral deposits targeting the richest seams first. In economic terms these return the biggest profit and in energy terms when it comes to oil, gas and coal, they return the highest levels of net energy. An inevitable consequence of this aspect of human nature commonly known as greed is that we have already used up the highest ERoEI fossil fuel resources and as time passes the ERoEI of new resources is steadily falling. This translates to a higher price required to bring on that marginal barrel of oil.

At the present time, our energy web comprises a myriad of different resources. The legacy supergiants – Ghawar, Black Thunder and Urengoy et al – are still there in the mix supplemented by a vast range of lower ERoEI (more expensive) resources. The greatest risk to human society today is the notion that we can somehow replace high ERoEI fossil fuels with new renewable energies like solar PV and biofuels. These exist within the energy web because they are subsidised by the co-existing high ERoEI fossil fuels. The subsidy occurs at multiple levels from fossil fuels used to create the renewable devices and biofuels to fossil fuels providing the load balancing services. Fossil fuels provide the monetary wealth to pay the subsidies. Society is at great risk from Greens promoting the new renewable agenda to politicians and school children whilst ignoring the thermodynamic impossibility of current solar PV technology and biofuels ever being able to power human society unaided. The mass closure of coal fired power stations may prove to be fatal for many should blackouts occur.

Wind power, and in particular high altitude wind power, may be different although in the case of ground-based wind turbines care must be taken in moving offshore to ever larger devices that consume ever larger quantities of energy in their creation. And to be viable, ground based turbines must be able to prove they can deliver dispatchable power without subsidies.

It is proposed that money was invented as a means of exchange for the work energy does on our behalf. If we lived in a society with a single global currency (the EJ) and without taxes or subsidies, then money may represent a fair proxy for ERoEI although distortions would remain from the different efficiencies with which that money (EJ) was spent. However, in the real world, different currencies, interest rates, debts, taxes and subsidies exist that allow the thermodynamic rules of the energy world to be bent, albeit temporarily. We are at risk of exchanging gold for dirt.

Acknowledgement

The post was much improved by comments provided by Prof Charles Hall.

References

[1] Richard Heinberg: The Party’s Over – oil, war and the fate of industrial societies. Pub by Clairview 2003

[2] David J. Murphy 1,*, Charles A.S. Hall 2, Michael Dale 3 and Cutler Cleveland 4: Order from Chaos: A Preliminary Protocol for Determining the EROI of Fuels (2011): Sustainability 2011, 3, 1888-1907; doi:10.3390/su3101888

[3] Ferruccio Ferroni and Robert J. Hopkirk 2016: Energy Return on Energy Invested (ERoEI) for photovoltaic solar systems in regions of moderate insolation: Energy Policy 94 (2016) 336–344

[4] Charles A.S. Hall n, Jessica G. Lambert, Stephen B. Balogh: EROI of different fuels and the implications for society: Energy Policy 64 (2014) 141–152

[5] D. Weißbacha,b, G. Ruprechta, A. Hukea,c, K. Czerskia,b, S. Gottlieba, A. Husseina,d (Preprint): Energy intensities, EROIs, and energy payback times of electricity generating power plants





It’s the nett energy George…..

7 02 2016

George-Monbiot-L

George Monbiot

George Monbiot has written another piece on the current oil situation, but whilst I agree mostly with what he says, he still doesn’t ‘get it’………

Oil, the industry that threatens us with destruction, is being bailed out with public money

By George Monbiot, published in the Guardian 3rd February 2016

Those of us who predicted, during the first years of this century, an imminent peak in global oil supplies could not have been more wrong. People like the energy consultant Daniel Yergin, with whom I disputed the topic, appear to have been right: growth, he said, would continue for many years, unless governments intervened.

Oil appeared to peak in the United States in 1970, after which production fell for 40 years. That, we assumed, was the end of the story. But through fracking and horizontal drilling, production last year returned to the level it reached in 1969. Twelve years ago, the Texas oil tycoon T. Boone Pickens announced that “never again will we pump more than 82 million barrels”. By the end of 2015, daily world production reached 97 million.

Following one of those links, I have to admit, surprised me…..  I had no idea the US’ oil production had almost reached its 1970 peak….. I may have confused how much they were extracting with what they were consuming. And, that chart is already out of date, the extraction rate is now in freefall…

usoilprod

What everyone who comments on this fails to say is that whilst the numbers of barrels tabled in their spreadsheets might well be there, and they may be following the money, absolutely nobody is following the nett number of Megajoules.  A barrel of oil from the last dot on the above chart may well contain less than a quarter of the nett energy content of one from a dot at the toe of the curve.

George then adds….:

Saudi Arabia has opened its taps, to try to destroy the competition and sustain its market share: a strategy that some peak oil advocates once argued was impossible.

Methinks he should visit Gail Tverberg’s site for proper analysis….

saudiexport

Saudi Arabia has been pumping flat out for years, with no discernible market flooding power.  It may in fact be trying very hard to meet its own fast growing domestic demand which is having an obvious impact on how much it is exporting, which is discernably less than it was way back in 1980……. so how can you blame them for flooding the market?

George continues with…..:

Instead of a collapse in the supply of oil, we confront the opposite crisis: we’re drowning in the stuff. The reasons for the price crash – an astonishing slide from $115 a barrel to $30 over the past 20 months – are complex: among them are weaker demand in China and a strong dollar. But an analysis by the World Bank finds that changes in supply have been a much greater factor than changes in demand.

Whilst Gail Tverberg says…..:

Some people talk about peak energy (or oil) supply. They expect high prices and more demand than supply. Other people talk about energy demand hitting a peak many years from now, perhaps when most of us have electric cars.

Neither of these views is correct. The real situation is that we right now seem to be reaching peak energy demand through low commodity prices. I see evidence of this in the historical energy data recently updated by BP (BP Statistical Review of World Energy 2015).

Growth in world energy consumption is clearly slowing. In fact, growth in energy consumption was only 0.9% in 2014. This is far below the 2.3% growth we would expect, based on recent past patterns. In fact, energy consumption in 2012 and 2013 also grew at lower than the expected 2.3% growth rate (2012 – 1.4%; 2013 – 1.8%).

Figure 1- Resource consumption by part of the world. Canada etc. grouping also includes Norway, Australia, and South Africa. Based on BP Statistical Review of World Energy 2015 data.

Recently, I wrote that economic growth eventually runs into limits. The symptoms we should expect are similar to the patterns we have been seeing recently (Why We Have an Oversupply of Almost Everything (Oil, labor, capital, etc.)). It seems to me that the patterns in BP’s new data are also of the kind that we would expect to be seeing, if we are hitting limits that are causing low commodity prices.

Of course, people like George who want to keep growth going, only using wind and nuclear power, don’t understand we are hitting limits.

When oil hit $147 at the time of the GFC, it literally bankrupted the economy. Having hit peak conventional oil, trillions of dollars had to be invested (read, borrowed…) to capitalise on the much higher hanging and less energetic fruit. Which made us get less with more, when we should be doing the exact opposite, doing more with less…..

George then has a big whinge about fossil subsidies at the expense of renewables.  The way I see it however, is that as all renewables are manufactured with fossil fuels, as they get cheaper, the costs of making the renewables also goes down, so that to some extent, any fossil subsidy is a hidden renewables subsidy…..  Furthermore, without further subsidies, oil and coal companies will go bust to which George says….:

A falling oil price drags down the price of gas, exposing coal mining companies to the risk of bankruptcy: good riddance to them.

Which, George, unfortunately also means good riddance to renewables….  He then ends with…….:

So they lock us into the 20th Century, into industrial decline and air pollution, stranded assets and – through climate change – systemic collapse. Governments of this country cannot resist the future forever. Eventually they will succumb to the inexorable logic, and recognise that most of the vast accretions of fossil plant life in the Earth’s crust must be left where they are. And those massive expenditures of public money will prove to be worthless.

Crises expose corruption: that is one of the basic lessons of politics. The oil price crisis finds politicians with their free-market trousers round their ankles. When your friends are in trouble, the rigours imposed religiously upon the poor and public services suddenly turn out to be negotiable. Throw money at them, trash their competitors, rig the outcome: those who deserve the least receive the most.

At last……  George recognises systemic collapse, for all the wrong reasons unfortunately. It may look like corruption to him, but it sure as hell looks like limits to growth to me.





What it would take for the US to run on 100% renewable energy

11 06 2015

The internet never ceases to amaze me as a source of hopium.  This article on vox, Here’s what it would take for the US to run on 100% renewable energy, manages to knock the wind out of the techno-utopian belief that we could run Business as Usual with renewables, even though it totally misses the most important point about why it can’t be done…....

It sets the scene with:

It is technically and economically feasible to run the US economy entirely on renewable energy, and to do so by 2050. That is the conclusion of a new study in the journal Energy & Environmental Science, authored by Stanford scholar Mark Z. Jacobson and nine colleagues.

Jacobson is well-known for his ambitious and controversial work on renewable energy. In 2001 he published, with Mark A. Delucchi, a two-part paper (one, two) on “providing all global energy with wind, water, and solar power.” In 2013 he published a feasibility study on moving New York state entirely to renewables, and in 2014 he created a road map for California to do the same.

This road map looks like this:

jacobson-us-renewables-2015At least, this road map shows a decline in total energy use over the period to 2050, which is fine, we absolutely have to reduce energy consumption.  Except of course I think we need to do this by at least 90%, but who’s splitting hairs…?

The author, , then goes on to explain what is required to do this:

The core of the plan is to electrify everything, including sectors that currently run partially or entirely on liquid fossil fuels. That means shifting transportation, heating/cooling, and industry to run on electric power.

Electrifying everything produces an enormous drop in projected demand, since the energy-to-work conversion of electric motors is much more efficient than combustion motors, which lose a ton of energy to heat. So the amount of energy necessary to meet projected demand drops by a third just from the conversion. With some additional, relatively modest efficiency measures, total demand relative to BAU drops 39.3 percent. That’s a much lower target for WWS to meet.

Fine……. so far.

So how could the economy be electrified on this ambitious timeline? Brace yourself:

Heating, drying, and cooking in the residential and commercial sectors: by 2020, all new devices and machines are powered by electricity. …

Large-scale waterborne freight transport: by 2020–2025, all new ships are electrified and/or use electrolytic hydrogen, all new port operations are electrified, and port retro- electrification is well underway. …

Rail and bus transport: by 2025, all new trains and buses are electrified. …

Off-road transport, small-scale marine: by 2025 to 2030, all new production is electrified. …

Heavy-duty truck transport: by 2025 to 2030, all new vehicles are electrified or use electrolytic hydrogen. …

Light-duty on-road transport: by 2025–2030, all new vehicles are electrified. …

Short-haul aircraft: by 2035, all new small, short-range planes are battery- or electrolytic-hydrogen powered. …

Long-haul aircraft: by 2040, all remaining new aircraft are electrolytic cryogenic hydrogen … with electricity power for idling, taxiing, and internal power….

Electrolytic cryogenic hydrogen?  My eyes glazed over here……….

Here’s what the paper says:

Power plants: by 2020, no more construction of new coal, nuclear, natural gas, or biomass fired power plants; all new power plants built are WWS.

2020 is just FIVE YEARS away………  but who’s counting?

…to meet most energy demand with wind and solar, you have to radically overbuild electrical generation capacity. To wit: the authors estimate that total US energy demand in 2050 will average 2.6 terawatts. To produce that much energy, they propose building power plants with a total of 6.5 TW of capacity. By way of comparison, the US currently has about 1.2 TW of installed electric generation capacity, so this plan would involve expanding generation capacity fivefold in 35 years.

Here’s what that would require:

… 328,000 new onshore 5 MW wind turbines (providing 30.9% of U.S. energy for all purposes), 156,200 off-shore 5 MW wind turbines (19.1%), 46,480 50 MW new utility-scale solar-PV power plants (30.7%), 2,273 100 MW utility-scale CSP power plants (7.3%), 75.2 million 5 kW residential rooftop PV systems (3.98%), 2.75 million 100 kW commercial/government rooftop systems (3.2%), 208 100 MW geothermal plants (1.23%), 36,050 0.75 MW wave devices (0.37%), 8,800 1 MW tidal turbines (0.14%), and 3 new hydroelectric power plants (all in Alaska).

That will meet average demand. Then you need 1,364 additional new CSP plants and 9,380 50 MW solar-thermal collection systems (“for heat storage in soil”) “to produce peaking power, to account for additional loads due to losses in and out of storage, and to ensure reliability of the grid.”

Is that realistic? asks Roberts……

Uh, no says Roberts….. No it isn’t. The authors inadvertently give away the game:

We do not believe a technical or economic barrier exists to ramping up production of WWS technologies, as history suggests that rapid ramp-ups of production can occur given strong enough political will. For example during World War II, aircraft production increased from nearly zero to 330,000 over five years.

The phrase “given strong enough political will” is open-ended enough to allow virtually anything through. But what would create this political will, equal to what gripped the US in the wake of the Pearl Harbor attack? The authors don’t say much about it, other than a hopeful note at the end that their quantification of the benefits of such a transition “should reduce social and political barriers to implementing the roadmaps.”

But here’s the key thing for me.  exactly how would the US build an increasing quantity of renewables, growing year after year, while reducing fossil fuel use, year after year, at the same time..?  And we all know how much fossil energy it takes to build all those wind turbines…..

Something major would have to be abandoned.  Like maybe the US military?  After all, once the Arabs’ oil is no longer needed, it won’t need ‘defending’!  Dream on.  This is no Pearl Harbor.  This is civilisational change…..  and the only other time we’ve had change on this scale was when…..  fossil fuels were discovered and exploited!  I’m definitely not holding my breath, but you already knew this.





Less than the sum of its parts: Rethinking “all of the above” clean energy

6 06 2015

Well, this is different.  If you needed more proof of why I think going 100% renewables is pure fantasy, this new way of parsing the facts using Capacity Factor should convince you.  Sometimes, even the obvious takes time to become obvious!  Mind you, I can’t agree with “build wind not solar”, because some places have no wind and loads of solar (and vice versa).  In the end, renewables are best in standalone systems, and even then, will only ‘solve’ our energy problems for only as long as we have fossil fuels to work the system, and we can’t afford to burn any more.  We can’t even afford the financial system to pay for it, and certainly not the nuclear grid these guys at Brave New Climate believe in……

Originally published over at Brave New Climate.

Guest Post by John Morgan. John is Chief Scientist at a Sydney startup developing smart grid and grid scale energy storage technologies.  You can follow John on twitter at @JohnDPMorgan.


The fastest path to decarbonization would seem to be combining every kind of low carbon energy available – the so-called “all of the above” camp of clean energy advocacy.  The argument runs that different kinds of clean energy are complementary and we should build as much of each as we can manage.  This is not in fact the case, and I’ll show that a mix of wind and solar significantly decreases the total share of energy that all renewables can capture.  The “all of the above” approach to emissions reduction needs to be reconsidered.

In a recent essay Breakthrough Institute writers Jesse Jenkins and Alex Trembath have described a simple limit on the maximum contribution of wind and solar energy: it is increasingly difficult for the market share of variable renewable energy [VRE] sources to exceed their capacity factor.  For instance, if wind has a capacity factor of 35%, this says it is very difficult to increase wind to more than 35% of electrical energy.  Lets look at why this is so, and extend the principle to a mix of renewables.

The capacity factor (CF) is the fraction of ‘nameplate capacity’ (maximum output) a wind turbine or solar generator produces over time, due to variation in wind, or sunlight.  Wind might typically have a CF of 35%, solar a CF of 15% (and I’ll use these nominal values throughout).

Jesse and Alex’s “CF% = market share” rule arises because it marks the point in the build out of variable renewables at which the occasional full output of wind and solar generators exceeds the total demand on the grid.

At this point it gets very hard to add additional wind or solar.  If output exceeds demand, production must be curtailed, energy stored, or consumers incentivized to use the excess energy.  Curtailment is a direct economic loss to the generators. So is raising demand by lowering prices.  Energy storage is very expensive and for practical purposes technically unachievable at the scale required.  It also degrades the EROEI of these generators to unworkable levels.

Jesse and Alex make this argument in detail, backed up with real world data for fully connected grids (i.e. not limited by State boundaries), with necessary qualifications, and I urge you to read their essay.

The “CF% = market share” boundary is a real limit on growth of wind and solar.  Its not impossible to exceed it, just very difficult and expensive. Its an inflexion point; bit like peak oil, its where the easy growth ends.  And the difficulties are felt well before the threshold is crossed.  I’ve referred to this limit elsewhere as the “event horizon” of renewable energy.

So if wind is limited to say 35% of energy, and solar to 15%, can we add them together and achieve 50% share?  The Breakthrough authors seem to think so, writing that “this threshold indicates that wind and solar may be able to supply anywhere from a third to a half of all electricity needs”.  That would be a very considerable addition of low carbon energy.  But unfortunately this is not the case.

Here’s the problem with adding solar: it produces about half as much energy as wind for the same capacity.  And the capacity factor rule sets a limit on total variable renewable capacity.  So at the limit solar capacity is not additive to wind, it displaces wind, while producing less energy.  Any amount of solar lowers the share of energy that wind and solar together can acquire, and the optimal mix for decarbonization is all wind and no solar.

This is a general corollary to the capacity factor rule – adding lower capacity factor generation to the mix reduces the potential share of variable renewable energy.  It is the energy equivalent of Gresham’s Law – “Bad energy drives out good”.  Far from targeting a “mix of renewables”, we are better off targeting just the one with the highest capacity factor.  We should build wind and not solar.

You can see this dynamic in the following figure, which plots the limiting share of wind and solar energy (VRE) in the grid as a function of solar’s share of wind and solar capacity.  Adding solar capacity cannibalizes wind capacity, and reduces the total amount of low carbon energy that these sources can ultimately provide.  Solar is not additive to wind; its subtractive.

The situation becomes even clearer if we shift focus from installed capacity to energy delivered.  In the plot below, the x-axis now shows the fraction of wind and solar energy that is produced by solar.

Introducing solar energy into the mix causes a rapid drop in the maximum grid penetration of all variable renewable energy.  Wind alone could potentially achieve 35% of grid energy share.  But with 50% solar, the maximum share that wind and solar together can achieve is just 21%.

In other words, building out solar effectively robs us of a whole climate stabilization “wedge”.

It should be remarked that this capacity factor rule sets too optimistic a limit.  The Breakthrough writers cite estimates that only 55%-60% of grid energy could be replaced by variable sources, due to stability requirements.  This means VRE share will struggle to exceed 60% of capacity factor, and the limits described above will be reduced by that factor.  So while wind alone could achieve up to about 21% of all electricity, a 50-50 mix of solar and wind is practically limited to only 12%.

This is a lot to give away.

So long as we only have a small amount of solar and wind we can build as much of either as we like.  The limit only becomes apparent at higher penetration.  But this happens much more quickly if there’s a lot of solar in the mix.

There may be good reasons to build solar in the early stages of a clean energy expansion.  The rate of emissions reduction matters, and while supply chains are developing, building both solar and wind might help.  But if this trajectory is to continue we will need to shift resources to wind fairly early on, and allow solar capacity to decline.

This should prompt a rethink of the simplistic “all of the above” response to emissions reduction, and the popular notion that there should be a mix of renewables.  If it doesn’t even work for wind and solar, does it work anywhere at all?  Its time to pick some winners, and support for renewable energy at scale should increasingly favour wind over solar.

And we should also think about how to decarbonise the remaining eighty percent of the grid that variable renewables can’t touch.





Wind turbines hit limits to growth before 50% wind power penetration

2 03 2015

Here is another blogpost clearly explaining the limits of renewable energy using mathematics… you know, that discipline you cannot argue with?  Originally published at Energy Skeptic dot com where loads of other interesting stuff on energy matters are accessible.  I highly recommend that site to all my DTM followers…..

thisisweherewindturbinescomefrom


Material requirements of 50% wind power in the USA hit limits to growth

Wind turbines can’t be made forever because natural gas, coal, oil, uranium (thorium), neodymium, and other energy resources and minerals needed for wind turbines are finite, and the energy to recycle is limited.

Oil, the master resource, coal, and natural gas are required to make the millions of tons of steel, copper, fiberglass, plastic, epoxy, and concrete as well as deliver and maintain hundreds of thousands of wind turbines providing 50% or more of electricity as fossil fuels decline.

2,029,104,500 MWh = Wind power to equal 50% of annual electricity generation in 2013 (4,058,209,000 MWh / 2)
5,606.4 MWh power per year per 2 MW turbine (2 MW * .32 national average capacity * 24 hours * 365 days) summer
361,926 Number of 2 MW turbines required (2,029,104,500 MWh / 5,606.4 MWh) You’d need 531,318 wind turbines to allow for the lowest capacity of .218 in august 2013 (EIA).
Area required 104,586 square miles — the entire state of Colorado (361,926 2 MW turbines * 2 * 92.47 acres per MW) (AWEO)
Materials per 2 MW turbine in short tons: 265.5 steel, 1025.5 concrete, 39 iron, 3 copper, 24.3 fiberglass, 10 epoxy, 2.4 plastic (average of Elsam, Guezuraga), and rare earth metals neodymium 800 pounds, dysprosium 130 pounds (ED).
Total amount of materials needed for 361,926 wind turbines in short tons: 96,091,353 steel, 371,155,113 concrete containing 74,213,022 cement (20% of concrete), 144,770 tons neodymium, 23,525 dysprosium, 14,115,114 iron, 1,085,778 copper, 8,794,802 fiberglass, 3,619,260 epoxy, 868,622 plastic
Annual steel production world-wide 1,833,395 tons in 2014 (worldsteel) = 52 years of world steel production (96,092,353 / 1,833,395)
Annual cement production USA 142,464,000 tons (USGS) = 52% of annual cement production (roads, buildings, sewers, and other infrastructure will suffer)
Neodymium world production is 7,840 tons/year. Windmill turbines would require 18.5 years of production. Dysprosium production is 112 tons/year requiring 210 years of dysprosium production (ED).
Fossil energy required to build windmills: The vehicles that mine iron ore run on diesel. Vehicles and equipment that process iron ore are mostly made of steel. Iron and steel are made by blast furnace or direct reduction using coal or natural gas. Imported steel arrives on ships burning diesel. Cement (20% of concrete) is made in a kiln using coal or natural gas. Fiberglass, epoxy, and plastic are made out of petroleum.

If the plan is to build 150% wind power to increase the capacity credit for reliable power, or immigration and birth rates increase the US population to 1 billion as expected in census projections by 2100, triple all of the above figures. Since the rest of the world also wants wind power and have increasing populations, perhaps multiplying by 10 would be more realistic, or by 12, since many material requirements were left out (i.e. transmission / distribution lines and towers, substations, roads, etc).

ED. 2015. Neodymium. Dysprosium. ElementsDatabase.org

EIA. 2015. Table 6.7.B. Capacity Factors for Utility Scale Generators Not Primarily Using Fossil Fuels, January 2008-November 2014. U.S. Energy Information Administration.

Prieto, P. A. 21 Oct 2008. Solar + Wind in Spain/ World. Closing the growing gap? ASPO International conference.

USGS. 2011. Cement production. United States Geological Society. 127,200,000 long tons converted to 142,464,000 short tons (2,000 lbs)

Worldsteel. 2014. Monthly Crude Steel Production 2014. Pig iron 2013 + DR 2013. worldsteel.org (converted from long to short tons).





Wind Blowing Nowhere

24 01 2015

I’ve just found this amazing post on Euan Mears’ excellent Energy Matters blog that clearly demonstrates, with real data, that anyone who believes renewables can run Business as Usual are just plain dreaming.

In much of Europe energy policy is being formulated by policymakers who assume that combining wind generation over large areas will flatten out the spikes and fill in the troughs and thereby allow wind to be “harnessed to provide reliable electricity” as the European Wind Energy Association tells them it will:

The wind does not blow continuously, yet there is little overall impact if the wind stops blowing somewhere – it is always blowing somewhere else. Thus, wind can be harnessed to provide reliable electricity even though the wind is not available 100% of the time at one particular site.

Here we will review whether this assumption is valid. We will do so by progressively combining hourly wind generation data for 2013 for nine countries in Western Europe downloaded from the excellent data base compiled by Paul-Frederik Bach, paying special attention to periods when “the wind stops blowing somewhere”. The nine countries are Belgium, the Czech Republic, Denmark, Finland, France, Ireland, Germany, Spain and the UK, which together cover a land area of 2.3 million square kilometers and extend over distances of 2,000 kilometers east-west and 4,000 kilometers north-south:

Figure 1:  The nine countries

We begin with Spain, Europe’s largest producer of wind power in 2013. Here is Spain’s hourly wind generation for the year. Four periods of low wind output are numbered for reference:

Figure 2:  Hourly wind generation, Spain, 2013

Now we will add Germany, Europe’s second-largest wind power producer in 2013. We find that Spanish low wind output period 4 was more than offset by a coincident German wind spike. Spanish low wind periods 1, 2 and 3, however, were not.

Figure 3:  Hourly wind generation, Spain + Germany, 2013

Now we add UK, the third largest producer in 2013. Wind generation in UK during periods 1, 2 and 3 was also minimal:

Figure 4:  Hourly wind generation, Spain + Germany + UK, 2013

As it was in France, the fourth largest producer:

Figure 5:  Hourly wind generation, Spain + Germany + UK + France, 2013

And also in the other five countries, which I’ve combined for convenience:

Figure 6:  Hourly wind generation, nine countries combined, 2013

Figure 7 is a blowup of the period between February 2 and 15, which covers low wind period 2. According to these results the wind died to a whisper all over Western Europe in the early hours of February 8th:

Figure 7: Wind generation, nine countries combined, February 2013

These results are, however, potentially misleading because of the large differences in output between the different countries. The wind could have been blowing in Finland and the Czech Republic but we wouldn’t see it in Figure 7 because the output from these countries is still swamped by the larger producers. To level the playing field I normalized the data by setting maximum 2013 wind generation to 100% and the minimum to 0% in each country, so that Germany, for example, scores 100% with 26,000MW output and 50% with 13,000MW while Finland scores 100% with only 222MW and 50% with only 111MW. Expressing generation as a percentage of maximum output gives us a reasonably good proxy for wind speed.

Replotting Figure 7 using these percentages yields the results shown in Figure 8 (the maximum theoretical output for the nine countries combined is 900%, incidentally). We find that the wind was in fact still blowing in Ireland during the low-wind period on February 8th, but usually at less than 50% of maximum.

Figure 8:  Percent of maximum wind generation, February 2013

But even Ireland was not blessed with much in the way of wind at the time of minimum output, which occurred at 5 am. Figure 10 plots the percentage-of-maximum values for the individual countries at 5 am on the map of Europe. If we assume that less than 5% signifies “no wind” there was at this time no wind over an area up to 1,000 km wide extending from Gibraltar at least to the northern tip of Denmark and probably as far north as the White Sea:

Figure 9:  Map of percent of maximum wind generation, February 2013

During this period the wind was clearly not blowing “somewhere else”, and there are other periods like it.

Combining wind generation from the nine countries has also not smoothed out the spikes. The final product looks just as spiky as the data from Spain we began with; the spikes have just shifted position:

Figure 10: Spain wind generation vs. combined generation in all nine countries, 2013 (scales adjusted for visual similarity)

Obviously combining wind generation in Western Europe is not going to provide the “reliable electricity” its backers claim it will. Integrating European wind into a European grid will in fact pose just as many problems as integrating UK wind into the UK grid or Scottish wind into the Scottish grid, but on a larger scale. We will take a brief look at this issue before concluding.

Integrating the combined wind output from the nine countries into a European grid  would not have posed any insurmountable difficulties in 2013 because wind was still a minor player, supplying only 8.8% of demand:

Figure 11: Wind generation vs. demand, nine countries combined

But integration becomes progressively more problematic at higher levels of wind penetration. I simulated higher levels by factoring up 2013 wind generation with the results shown on Figure 12, which plots the percentage of demand supplied by wind in the nine countries in each hourly period. Twenty percent wind penetration looks as if it might be achievable; forty percent doesn’t.

Figure 12:  Percent of hourly demand supplied by wind at different levels of wind penetration using 2013 data

Finally, many thanks to Hubert Flocard, who recently performed a parallel study and graciously gave Energy Matters permission to re-invent the wheel, plus a hat tip to Hugh Sharman for bringing Hubert’s work to our attention.