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!