Thursday, October 02, 2014

Calibrating Solar's Growth Potential

  • A new report from the International Energy Agency suggests the possibility of solar power becoming the world's largest electricity source by 2050.
  • It is noteworthy that IEA thinks this could happen, but the growth rates required, let alone the policies necessary to support them, will be challenging to sustain.
In the wake of last month's UN Climate Summit in New York City, Monday's report from the International Energy Agency (IEA) on "How solar energy could be the largest source of electricity by mid-century" ought to be welcome news. At the same time, it conflicts with perceptions that some countries are already farther along than that. So IEA's indication of the feasibility of generating 26% of global electricity from solar energy by 2050 either looks quite ambitious or quite conservative, depending on your current perspective.

For me it always comes down to the numbers, without which it's impossible to grasp systems on the scale and complexity of global energy. IEA's high-solar roadmap--it's not a forecast--includes significant contributions from both solar photovoltaic power (PV) and solar thermal electricity (STE)--often referred to as concentrating solar power, or CSP--with the former making up 16% of global electricity at mid-century and the latter around 10%. As the detailed report from IEA indicates, achieving the headline result would require global installed PV capacity to grow 35-fold between 2013 and 2050, equivalent to an average of 124 Gigawatts (GW) per year of additions, peaking at "200 GW/yr between 2025 and 2040." That's a 6x increase in installations over last year.

To put that in a US electricity generation perspective, IEA projects that the US would have to hit one million GW-hours per year from PV--roughly what we currently get from natural gas power plants--by around 2035 to meet its share of the anticipated global solar buildup. US solar installations are on a record-setting pace of nearly 7 GW this year, but matching natural gas would require 120x growth in solar generation, or a sustained compound average growth rate over 25% for the next 20-plus years. That's not impossible, as recent PV growth has been even higher, but it won't be easy to continue indefinitely, especially without further improvements in the technology, and in energy storage.

The solar thermal portion of IEA's technology roadmap looks like a much tougher challenge. STE has been losing ground to PV lately, as the costs of the latter have fallen much faster than the former, for reasons that aren't hard to understand. Making PV modules cheaper and more efficient is analogous to improving computer chip manufacturing, while making STE cheaper and more efficient is more similar to manufacturing cheaper, more efficient cars or appliances.

One of the main reasons IEA appears to have concluded that STE could suddenly start competing with PV again is its inherent thermal energy storage capability, which enables STE to supply electricity after the sun has set. While I wouldn't discount that, it looked like a bigger benefit a few years ago, before electricity storage technology started to improve. Storage of all types is still expensive, which helps explain why fast-reacting natural gas power plants offer important synergies for integrating intermittent renewables like wind and solar power. However, it looks like a reasonable bet today that batteries and other non-mechanical energy storage technologies will improve faster than thermal storage in the decades ahead.

The upshot of all this is that getting to 16% of global electricity from PV by 2050 is a stretch, and the 10% contribution from STE looks like even more than a stretch. So how does that square with recent reports that Germany--hardly a sun-worshipper's paradise--got "half its energy from solar" for a few weeks this summer? A recent post on The Energy Collective does a better job of clarifying the significance of that than I could, providing links to German government data indicating that solar's average contribution in 2013 was just 4.5% of electricity--hence less than half that in terms of total energy consumption. The author extrapolates that at current rates of annual installations, it would take Germany nearly a century to get to 50% of its electricity from the sun.

Much can happen in 35 years that we wouldn't anticipate today. For now, solar PV looks like the energy technology to beat, in terms of low lifecycle greenhouse gas emissions and long-run cost trends. But whether it reaches the levels of market penetration the IEA's report suggests are possible, or tops out at less than 5% of global electricity supply, as their baseline scenario assumes, it must function within an energy mix that includes other technologies, such as fossil fuels, nuclear power and non-solar renewables. And that's true whether or not electric vehicles take off in a big way, which would significantly increase electricity demand and make the IEA's high-end solar targets even more difficult to reach.


Anonymous said...

This was a very eye opening and thought provoking article. Solar power as always seen to be the best way out of our power shortage but it also seems to be a very long a hard process. I think it should be more forcefully encouraged through each and every major country. Although the 35 years seems like a long time, it can go by very fast and serious action needs to be taken. Otherwise, this operation will be as you said "ambitious".

Anonymous said...

Azhar Omar

The per-unit cost of electricity provided by power companies will begin to rise this has been occurring in many countries as costly infrastructure demands combine with stagnating or falling demand caused by the penetration of distributed power systems. These two merging dynamics – dropping solar costs and rising utility rates for electricity. Although solar power is an immature, in 35 years time I believe it will greater established power source.

Geoffrey Styles said...

I'd just point out that power demand in the developed world didn't stagnate because of distributed power, but due to recessions. Now, the combination of DG and energy efficiency are reducing the upside for utilities of the weak recoveries that are occurring. It's a tough dynamic, even for DG, because it's easier to gain share in a strong market.

Anonymous said...


This is a very informative article and one which brings to light a lot of thought provoking judgments on the IEAs statement that Solar energy may be the biggest energy source by the mid century. It is worth noting that some countries like the canary islands have already gone off the grid so to speak. Relying solely on renewable energy sources such as solar hydro and wind, which shows that in the 21 centenary this is already possible. They are however, smaller with less infrastructure and like the article suggests, with a move from gas powered car to electric one the demand for electricity will increase exponentially and thus lessen the likely hood of the world economy being able to source most of its energy from solar power in the coming years.

Sasha Tavares (14003423) said...

Solar energy growth potential conflicts with views that some countries are ready for it and others are not, therefore the possibility of solar energy becoming the world’s largest power source by 2050 from my point of view is conservative. This growth potential could be possible, but there are many obstacles to deal with such as: the growth rates required and the policies set up by governments necessary to support them. This is where the challenge lies. However, solar power is an attractive energy source and should be encouraged globally. With energy demand continuously increasing and the world’s limited resources, solar energy has the potential to become an important future conventional source of energy. The future appears to be exceedingly bright for PV and STE solar energy.

Michael Aguirre (14220602) said...

Thank you for this very intriguing post on energy.

I believe that solar energy is definitely a way forward in dealing with the current crisis of the demand for energy increasing. Recently, Eskom, the South African electricity provider, has been doing what is referred to "load shedding". This is when one area of a city, or a suburb, is switched off from the grid to decrease the load on the grid.

Eskom has been struggling to deal with the power usage in South Africa, as seen by the many television advertisements they post.

Therefore, a viable option for, and not only, Eskom would be to start creating this infrastructure that is being talked about (PV and STE solar) to increase the supply of energy.

The average amount of sunlight received in certain parts of South Africa is around 2500 hours. In comparison to the USA and Europe, South Africa receives about 220W/m2 of energy, with the USA and Europe being only 150 W/m2 and 100W/m2 respectively. [Source:]

With that said, I believe that solar power has a major benefit to countries in Africa, especially South Africa. Although the energy collected in the USA and europe is less, it could still provide the much needed alternative energy to those countries.

Geoffrey Styles said...

South Africa has excellent solar resource, comparable to the US southwest. Not surprising, considering good climate and latitude mirroring Southern California.

Marco van der Walt (14020140) said...

Thanks for a very enlightening article, however energy creation is a worldwide problem and I belief different countries should have different approaches. I believe that South Africa and Africa has the perfect climate for the usage of solar energy sources. On the other side in Europe countries has longer winters and less sun and might seek alternative solutions.
Currently South Africa’s power is generated by Eskom and is dependent on coal. South Africa is faced with 2 major problems namely deteriorated infrastructure and little maintenance and secondly reducing levels of available coal.
South Africa has been confronted with load shedding over the past few years and the growth in demand for electricity by a developing nation has added just more pressure.
South Africa needs to actively drive for alternative sources of power such as Solar energy, however that will only take effect if driven by legislation and policies instituted by Government. Unfortunately the owners of mines who produce coal are very much linked to the decision makers in Government and therefore transition to other resources such as solar energy I doubt will go as quickly as we all hope for.

Richard Roberts said...

This was a great article, however energy development is problem the world around. You would think that with the levels of technology we are currently at as a generation there should be many more options and ideas for renewable energy sources. the fact of the matter is though that the huge corporations involved in the distribution of today's energy reserves are making more and more money off the ever increasing demand for energy and the ever reducing supply of it and why would they want to stop themselves making money. However i think that South Africa as a country has the potential to invest and show the world how useful renewable energy such as solar power can be.

Geoffrey Styles said...

"the ever reducing supply of it"

It's hard to break the perception of energy scarcity that has dominated the last four decades, but the preponderance of energy data say it's time to do so. US proved oil reserves are at a 30 year high, because we're now producing oil directly from source rock, rather than just scarce and depleting conventional reservoirs. Global oil reserves today are 26% higher than 10 years ago, despite a 14% increase in annual consumption in the same period. Oil prices are sinking today because there's more supply than demand, and that's only partly due to a weak global economy.



And it's not just oil. Gas is surging from unconventional sources and from conventional reservoirs in unexpected places. Renewables like wind and solar are becoming cost-competitive in locations with good resources. The real "fact of the matter" is that while the cost of energy remains a challenge for many economies, and emissions are still a problem, we have more energy from more sources than we imagined possible. Logistics--getting energy from source to market reliably and cost-effectively--is turning out to be a much bigger problem than production or generation. We need a new mindset that matches this new reality.

u14007313 said...

It is an interesting, thought-provoking and informative article! The possibility of solar power becoming the world's greatest electricity source by the year 2050 is an exciting prospect - we rely far too much on oil, coal and other non-renewable reserves for our sources of fuel and the Earth is taking serious strain because of this.

Political unrest and instability is also becoming an increasingly worrying factor. We may not be able to rely on the availability of oil for much longer, and it's reassuring to know that, fortunately, we will not become stuck because of it!

I am pleased that the world is making inroads into discovering more environmentally-friendly means of generating electricity, and look forward to a cleaner, greener future!

marco said...

this is a interesting article. It gives hope to people that there are a different form of energy for the future than just coal. With all of the political unrest in the world the availability of oil, coal and etc. is not a guarantee. I think solar is the way for the future.

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Geoffrey Styles said...

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Geoffrey Styles said...

Dave Thompson wrote:
"I believe that solar energy will become the leading energy source in the next few years. It is good for the environment as well. If solar power is not the leading energy source in a few years I will be very surprised."

First, I deleted your comment for inclusion of a commercial link. If you'd like to advertise on this site, please contact me at the address shown.

Second, if you do the math on solar as a fraction of the overall energy mix, it is clear that it cannot "become the leading energy source in the next few years." Suggesting otherwise is hype. However, there's a good chance solar will be a major energy source within 20 years, and that's a good thing. How big it gets will depend on the availability of cheap, high-capacity energy storage.

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Geoffrey Styles said...

Stephen Brown wrote:
"Like you mentioned, many different advances could be made in the next 35 years. I'm excited to see improvements in solar cell efficiency that could make solar the preeminent clean power source in the US. I hope to be able to drive a luxury car completely powered by solar panels someday."

Inclusion of an unauthorized advertising link got the content of your note deleted. If you'd like to advertise on this site, please contact me at the email provided.

As for a "luxury car completely powered by solar panels", unless you meant stationary panels not on the vehicle the math is rather daunting. While engineering students can build solar prototypes that go long distances with just a driver and featherweight construction, the surface area of a car can't catch enough sun, even at much higher efficiencies than today, to drive a real-world car more than a few miles a day.


Solar Installers Las Vegas said...

I really like the information provided in this article, As increasing pollution and global warming we must choose the renewable resources as they never cause any harm to our environment. The solar power is considered as the new energy for us and it is a green power for the environment, We should encourage more people using it in the life. thanks