How Unsustainable is PV Solar Power?

27 10 2015

Hot on the heels of yesterday’s post about renewables being unable to even keep up with the growth of the internet’s energy consumption, along come a couple of other articles I just had to share…..

From Low Tech Magazine yet again is an article about the mushy numbers used to ‘prove’ PVs are the way to go in the future. Most followers of this blog will already know how I feel about this, however, this item has some interesting factoids I was not aware of that make a most interesting point.

Lower costs have spurred an increase in solar PV installments. According to the Renewables 2014 Global Status Report, a record of more than 39 gigawatt (GW) of solar PV capacity was added in 2013, which brings total (peak) capacity worldwide to 139 GW at the end of 2013. While this is not even enough to generate 1% of global electricity demand, the growth is impressive. Almost half of all PV capacity in operation today was added in the past two years (2012-2013). In 2014, an estimated 45 GW was added, bringing the total to 184 GW.

Solar PV total global capacitySolar PV total global capacity, 2004-2013. Source: Renewables 2014 Global Status Report.

According to these numbers, electricity generated by photovoltaic systems is 15 times less carbon-intensive than electricity generated by a natural gas plant (450 gCO2e/kWh), and at least 30 times less carbon-intensive than electricity generated by a coal plant (+1,000 gCO2e/kWh). The most-cited energy payback times (EPBT) for solar PV systems are between one and two years. It seems that photovoltaic power, around since the 1970s, is finally ready to take over the role of fossil fuels.

But, as the article goes to great lengths to explain, manufacturing has moved to China, and as was recently revealed, the biggest eighteen ships produce as much CO2 as all the cars in the world……… so shipping those panels (and inverters) from China to Australia, Europe, and the Americas is unbelievably polluting.

Less than 10 years ago, almost all solar panels were produced in Europe, Japan, and the USA. In 2013, Asia accounted for 87% of global production (up from 85% in 2012), with China producing 67% of the world total (62% in 2012). Europe’s share continued to fall, to 9% in 2013 (11% in 2012), while Japan’s share remained at 5% and the US share was only 2.6%.

Price of silicon solar cells wikipedia

Compared to Europe, Japan and the USA, the electric grid in China is about twice as carbon-intensive and about 50% less energy efficient. Because the manufacture of solar PV cells relies heavily on the use of electricity (for more than 95%) this means that in spite of the lower prices and the increasing efficiency, the production of solar cells has become more energy-intensive, resulting in longer energy payback times and higher greenhouse gas emissions. The geographical shift in manufacturing has made almost all life cycle analyses of solar PV panels obsolete, because they are based on a scenario of domestic manufacturing, either in Europe or in the United States.

Compared to the original manufacturing scenarios of Germany, Japan, Spain, and the USA, the carbon footprint and the energy payback time of Chinese PVs are almost doubled in the asian manufacturing scenario. The carbon footprint of the modules made in Spain (which has a cleaner grid than the average in Europe) is 37.3 and 31.8 gCO2e/kWh for mono-Si and multi-Si, respectively, while the energy payback times are 1.9 and 1.6 years. However, for the modules made in China, the carbon footprint is 72.2 and 69.2 gCO2e/kWh for mono-Si and multi-Si, respectively, while the energy payback times are 2.4 and 2.3 years.

Carbon footprints solar cells produced in china and europe

At least as important as the place of manufacturing is the place of installation. Considering that at the end of 2014, Germany had more solar PV installed than all Southern European nations combined, and twice as much as the entire United States, this number is not a worst-case scenario. It reflects the carbon intensity of most solar PV systems installed between 2009 and 2014. More critical researchers had already anticipated these results. A 2010 study refers to the 2008 consensus figure of 50 gCO2e/kWh mentioned above, and adds that “in less sunny locations, or in carbon-intensive economies, these emissions can be up to 2-4 times higher”. Taking the more recent figure of 30 gCO2e/kWh as a starting point, which reflects improvements in solar cell and manufacturing efficiency, this would be 60-120 gCO2e/kWh, which corresponds neatly with the numbers of the 2014 study.

Solar insolation in europe

Solar insolation in north america

Solar insolation in Europe and the USA. Source: SolarGIS.

So far, I expect most DTM readers already knew this….. but now for the clincher, and it’s growth, yet again totally unsustainable. The author calls this Energy cannibalism, a term I just love!

Solar PV electricity remains less carbon-intensive than conventional grid electricity, even when solar cells are manufactured in China and installed in countries with relatively low solar insolation. This seems to suggest that solar PV remains a good choice no matter where the panels are produced or installed. However, if we take into account the growth of the industry, the energy and carbon balance can quickly turn negative. That’s because at high growth rates, the energy and CO2 savings made by the cumulative installed capacity of solar PV systems can be cancelled out by the energy use and CO2 emissions from the production of new installed capacity.

For the deployment of solar PV systems to grow while remaining net greenhouse gas mitigators, they must grow at a rate slower than the inverse of their CO2 payback time. For example, if the average energy and CO2 payback times of a solar PV system are four years and the industry grows at a rate of 25%, no net energy is produced and no greenhouse gas emissions are offset. If the growth rate is higher than 25%, the aggregate of solar PV systems actually becomes a net CO2 and energy sink. In this scenario, the industry expands so fast that the energy savings and GHG emissions prevented by solar PV systems are negated to fabricate the next wave of solar PV systems.

Several studies have undertaken a dynamic life cycle analysis of renewable energy technologies. The results — which are valid for the period between 1998 and 2008 — are very sobering for those that have put their hopes on the carbon mitigation potential of solar PV power. A 2009 paper, which takes into account the geographical distribution of global solar PV installations, sets the maximum sustainable annual growth rate at 23%, while the actual average annual growth rate of solar PV between 1998 and 2008 was 40%. [16] [21]

This means that the net CO2 balance of solar PV was negative for the period 1998-2008. Solar PV power was growing too fast to be sustainable, and the aggregate of solar panels actually increased GHG emissions and energy use. According to the paper, the net CO2 emissions of the solar PV industry during those 10 years accounted to 800,000 tonnes of CO2.

Which totally puts paid to the hopes of ‘green people’ wanting a quick transition from coal to PVs. The faster it happens, the worse greenhouse emissions are…… Is this the ultimate limit to growth? I find the irony almost too much to bear. I heartily recommend reading the article at its original source where all the facts and figures are referenced. It makes for sobering reading……..

But wait there’s more. Just last night on TV I saw an item on 7:30 on ABC TV showing some guy who built a modern mansion with all the bells and whistles, 300m from the grid. he claims it was going to cost $200,000 to connect to the grid (seems rather excessive to me…) so decided to go off the grid. The TV item was about how we will all go off the grid within ten years, and look at this guy’s amazing green bling…… four inverters no less! Anyone with four inverters is using four times too much power (and hence energy), and he proudly claimed to have batteries capable of backing the whole lot for…. three days. I can guarantee he will soon be disappointed. Anything less than a week would not suit me, I’d opt for ten days. But then again, I don’t need four inverters, we’ll only have one. Watch it here.

Why am I so certain he will be disappointed? Well Giles Parkinson and Sophie Vorrath are, like me, not convinced your average electricity consumer understands any of the dilemmas they face.

So for those of us left, and interested in battery storage as a means of saving money, how do the numbers stack up?

Before tackling those numbers, it is worth noting that the numbers for battery storage are more complex than they may first appear.

Making the economics work will depend on how much your household consumes and when, the size of your solar array, if any, and the local tariff structure. Then you have to consider how you will use that battery, and how the grid might use it to.

Because batteries are left lying around doing nothing much of the time, ‘the sweet spot’ for consumers lies in the range of 3.5to 5.0 kWh/day. Or less, I would add. And that, my friends, leaves out 90% of the electricity consumers as they stand right now. That Adelaide guy in the 7:30 show is well out of his league, and when he’ll have to replace his underworked Li ion batteries after just 10 years, if he can still get some, he will be wondering why his green bling is so expensive to keep running… and to top it all off, the article raves about what will happen way out to 2030, assuming that business as usual will continue forever, and that there will still be a grid to hook up to, unlike Gail Tverberg, the optimist!

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The 5 key elements of sustainable transport

13 04 2014

The 5 key elements of sustainable transport, or rather ‘so called’ sustainable transport makes for interesting reading.  Some of this info doesn’t really make much sense to me…. like the C intensity of different flights (business and economy, short and long) as a function of emissions per kilometre.

Interestingly, the difference between a ‘small car’ (a car that can only do 35MPG is NOT a small car!  But then, this is written in/for the USA….) and a grid charged electric car is only 15g CO2e/km, or just 9%.  By that measure, the Suzuki Alto I drove in Tasmania emits far less than an electric car, unless that car is 100% solar recharged.  And then I’m doubtful, because since we now know solar has a shockingly low ERoEI, it might be even closer than we think.  I’m also surprised cycling’s numbers are as high as they are shown here.  Does a cyclist really consume a whole lot more food than a motorist?

The article also states “People who live in cities have lower transport emissions.  Fuel economy may be lower in city traffic but that is more than made up for by the fact that city dwellers drive far less.”  Well that depends……  since moving from the city to the country, I’ve actually halved how much I drive!  Then it continues with “In 1950 less than 30% of the world’s population lived in cites, by 2010 that figure was over 50%, and by 2030 it is expected to surpass 60%. This natural trend to urbanization is a huge opportunity to for lowering both distance travelled per person and the carbon intensity of that travel.”  Whoever wrote this has obviously no idea cities will eventually be abandoned for being too far from their food sources, and due to the fact that when grids go down, none of the lifts will work!  Nor the sewerage……..

Shrink That Footprint

sustainabletransport

Transport is responsible for around a seventh of greenhouse gas emissions globally. Of these emissions almost two thirds are the result of passenger travel while the rest is due to freight.

So passenger travel is a big deal for climate.

In the chart above, which comes from our new eBook Emit This, we compare carbon intensity of different types of passenger transport on a per passenger kilometre basis.  Using it we can explain some elements important to the development of a sustainable transport system.

1) Fuel Economy

Our chart today compares the carbon intensity of different transport modes, per passenger kilometre.  The better fuel economy gets the lower emissions go.  If you just look at the cars you’ll see the large car (15 MPG) has emissions almost three times that of the hybrid car (45 MPG).

By improving fuel economy we can get the same mileage while generating fewer emissions.  Something that is achieved by making engines more efficient, vehicles lighter and bodies more aerodynamic.  But even then combustion engines remain relatively inefficient and produce emissions at the tailpipe, so improving them is really just a stop-gap en-route to sustainable transport.

2) Occupancy

The cheapest and simplest way to lower the carbon intensity of a passenger kilometre is to stick more people in the vehicle.  In each of the figures above car occupancy is assumed to be an average of 1.6 passengers (including the driver).  But most cars are designed for 5 people.

If you take a look at the bus examples the importance of occupancy becomes even more stark.  The local bus example has emissions seven times higher than the school bus.  While there routes may vary a little they are both diesel buses.  The main difference is that the school bus has very high occupancy.

With notable exception of flying public transport tends to have quite low carbon emissions, due largely to having relatively high occupancy.

3) Electrification

In the absence of breakthroughs in second generation biofuels electrification is the most important pathway to low carbon transport.

Electric cars using low carbon power have footprints less than half that of the best hybrid, even after you account for their larger manufacturing footprint.  Right down the bottom of our chart is the high-speed EuroStar rail which used low carbon French electricity. Though not on our chart the lowest carbon transport on earth is probably electrified public transport in a place like Norway where electricity generation is almost carbon free.

While there is a natural tendency to obsess about the electrification of cars, there are lots of interesting innovations occurring in the electrification  of rail, motorbikes, scooters and bikes.

4) Pedal power

They may be a bit low tech for some, but when it comes to carbon emissions bicycles are pretty cutting edge.  Even when you account for the foodprint of excess energy used when cycling, the humble bike is incredibly low carbon.

Bikes have obvious limitations around speed and distance, but for short trips in places with good infrastructure they are hard to beat in terms of carbon. They also have a great synergy with public transport systems like intercity rail.

5) Urbanization

Each of the first four elements we have described above refers to improving the carbon intensity of transport.  But emissions are a function of both how we travel and how far we travel.  One thing that tackles both of these issues is the trend towards urbanization.

People who live in cities have lower transport emissions.  Fuel economy may be lower in city traffic but that is more than made up for by the fact that city dwellers drive far less.  Electrification of public transport is more economic and practical in cities.  Occupancy on public transport systems is much higher.  And access to infrastructure for both cycling and walking is often better.

In 1950 less than 30% of the world’s population lived in cites, by 2010 that figure was over 50%, and by 2030 it is expected to surpass 60%. This natural trend to urbanization is a huge opportunity to for lowering both distance travelled per person and the carbon intensity of that travel.

Those are our five elements of sustainable transport: fuel economy, occupancy, electrification, pedal power and urbanization.

Check out our free new eBook Emit This for more ideas on getting more life out of less carbon.

Source: Shrink That Footprint. Reproduced with permission.