Welcome to the age of diminishing returns

Friday, September 30, 2011

The renewable revolution

Worldwide growth of Photovoltaic and Wind installed power, by Emilio Martines. Data from IEA Photovoltaic Power Systems Programme, European Wind Energy Association and Earth Policy Institute.

For a change, here is a non-Cassandric post. Look at the data in the figure above, kindly provided by Emilio Martines, member of ASPO-Italy. The growth of photovoltaic and wind energy has been impressively fast during the past 2-3 decades. The log scale evidences the exponential growth of both technologies. There are no signs of slowdown, so far, despite recessions and the bad state of the economy. According to the graph, wind power grows of a factor 10 in less than 10 years, PV power takes little more than 5 years. At these rates, both wind and PC could reach the goal of one installed terawatt (TW) each around 2020.

Of course, the capacity factor of wind and PV is smaller than that of conventional sources, so that one TW of renewable power can produce considerably less energy than one TW of - say - a coal fired plant. Then, there is the question of storage and other issues. Nevertheless, the data are impressive, considering that the total electric power installed in the world today is around 2 TW. It is exactly the value of renewable peak power that we could reach by the end of the current decade. Are we seeing a glimpse of light at the end of the tunnel?

Obviously, nothing can grow exponentially forever. But we have nevertheless generated an energy revolution: renewable power has a market and it grows. It is a revolution that can't be stopped any more. It gives us a chance to replace fossil fuels before it is too late. It is a fighting chance, but we have it.


  1. Let's hope this growth isn't just a side effect of the last abundant fossile fuel period, as it could well be ...

  2. "renewables" are not renewable simply because they will never reproduce the devices necessary to capture the sun or wind. They are also not green because by using fossil fuels they devastate the environment no differently than cars or computers. Even using them as a transition to a much lower per capita energy use and more realistically renewable energy is adding more of an environmental burden to the future generations. Ugo Bardi's work is usually brilliant. I guess for this essay I must wear the cassandra mantle.
    I address this issue and include pictures of the environmental assault in Energy in the Real World with pictures of proof.

  3. I think it would be very interesting to plot alongside these the amount of subsidies (for production and installation) for this kind of renewable sources. I guess that will probably clarify much about why there are no signs of slowdown yet.

    It would also be quite naive at this stage to think that it is still possible that some things can keep growing exponentially indefinitely.

    I wonder if a Peak Renewables is likely to appear soon once governments realize they have no more money available for subsidizing.

  4. Yves, you are perfectly right: the growth of renewable IS fueled by fossil fuels. It is the best use of fossil fuel I can imagine and it repays itself very quickly

  5. John, thanks for donning the Cassandra cloak. I started to feel very lonely! But, in this case, I think you are too Cassandric. I went to see you site; you may be perfectly right in seeing us going back to Middle Ages, but that won't be because renewables can't pay for themselves in terms of energy. The latest results give better EROEIs for renewables than for fossil fuels. A PV plant can now repay itself in terms of energy in less than one year.

  6. ZZR you can find the chart you would like to see at this link


    You can see that subsidies for renewables (excluding biofuels) are less than 1/10 than the subsidies enjoyed by the fossil fuel industry. That for the US, at least. In Europe, probably, renewables enjoy a larger support, but even here I think that fossil fuels get the larger share

  7. One question about renewable electricity which I have never heard a credible answer is, how can renewables provide reliable 24 hour a day electricity on the scale we are used to today? Doesn't intermittent power result in an intermittent grid? Is there a sustainable, affordable and renewable way to store energy? Why is this ignored?

  8. All right Ugo, it is not the first article I have seen stating that renewables receive less subsidies than oil, and it is probably true. However, what I ask is not an historical evolution of the amount of subsidies received as a function of time for each energy source since they were first introduced to see how fair these subsidies are, but to analyse the actual conditions in which they compete today.

    More importantly, what I am interested to see is not the chart that have $ as a unit but $/kWh or $/toe. And the US case alone would probably be a bit too limited for this purpose, global statistics would be much better. Maybe I am asking for too much, though.

  9. It is funny that I am playing the anti-cassandra! about ZZR's question, I think there is a semantic problem. When we speak of "subsidies" we may mean monetary or energy subsidies. In the first case, monetary subsidies, we mean that renewables would not be marketable on their own. This we can see in two ways: one is as a scam perpetrated by evil lobbies with our money as taxpayers, the other as a wise investment in our future and for the benefit of our children that the market, alone, would not be able to do. Up to you to decide!

    Then, if we see subsidies in terms of energy, it is obvious that renewables are being built today using energy provided by fossil fuels. To me, as I said before, it looks like a wise idea on what to do with fossil fuels. It is like having a child; a child needs a mother and will not be able to generate children right away.

    That raises the question whether renewables will be able to repay the energy invested in their manufacturing. I think yes, absolutely yes. There are many papers that demonstrate this possibility. For instance:

    Fthenakis V.M., Raugei M., Held M. Update of environmental impacts and
    energy payback times of photovoltaics. 24th European Photovoltaic Solar Energy
    Conference (EU PVSEC), 2009; 6DO.10.5.

    This is possibly the most optimistic of the lot, measuring the EROEI of PV as around 40. But it is updated and based on the best technologies we have. So, I do believe that the EROEI of state of the art plants is - at the very least - around 10 in sunny regions.

  10. For Bilbo. It is strange that you see the question of storage and intermittency as "ignored". There is a huge amount of literature involved. In any case, renewable energy as it is produced today by PV or wind is a seasonal product; just like strawberries. Just as for strawberries, the fact of being seasonal doesn't mean that it doesn't have a market value. And, just as strawberries can be frozen and sold even for Christmas, renewable energy can be stored, although that has a cost.

    There is a lot of work on storage. In my view, the most promising approach for long term storage is based on compressed air (CAES). You can give a look to the work being done here:


    There is no doubt that energy storage at reasonable costs is possible, but we are still at the research stage; in my opinion we'll have to adapt to the variable output of renewable plants by developing demand management systems, part of the more general concept of "smart grid"

  11. Incidentally, I noticed the comments to this article reproduced on "EnergyBulletin". I commented as:

    It is very curious to see how many people still think that renewables have "a low EROEI". This is not true any more. Right now, renewables such as wind and PV have EROEIs comparable, and in many cases superior, to the values for fossil fuels. There is no reason why renewables shouldn't be able to produce enough energy to reproduce themselves. The idea that they can't seems to have originated from an old paper by Odum, but it is outdated. Please see my article on "the oil drum"


  12. A load of rubbish. These "renewable generators" take more energy to manufacture and maintain than they give back. They are manufactured using still relatively cheap fossil fuel.

  13. The graphs look superb, but there are important caveats to the final triumph of renewables:

    - The EROEI question: Charlie Hall and Pedro Prieto will soon publish their study on the EROEI of real-world, operating PV farms. Their value: 2.7, and that disregarding some costs assumed by the Chinese manufacturers of some key materials; this accounted the EROEI could drop to 2 or below. Apart from that, we should be aware that our present calculations of EROEI are based on the input energy sources presently to our reach. Let oil and/or gas get out of our input and our EROEIs will fall precipitously.

    - Wind potential: Carlos de Castro, from the University of Valladolid, and co-workers, have recently done a top-bottom approach to the amount of energy actually conveyed by the atmosphere lower boundary layer (up to the 160-m on reach of windmills) and it turns out that this energy is two or more orders of magnitude smaller than what it is usually assumed just considering wind locations as independent sources of energy, instead of being a part of the whole (incidentally, this paper has been discussed in The Oil Drum). The technical wind potential of planet Earth is finally equivalent to an average power of 1 Tw (we talk here about actually produced energy, not installed power). One Tw is fine, but this is the top of it. Much less than the 14 Tw presently consumed as primary energy all over the world, and that with our uneven consumption.

    So, really, I do not feel very confident on the renewable power to change things....


  14. Thank you, Harquebus, for passing to us your superior wisdom. Now we are all enlightened.

  15. Antonio, there is a spread of studies on the EROEIs and the ultimate potentials of renewables. The one by Pedro Prieto and Charles Hall represents a low extreme with respect to the ones by Fthenakis, Raugei and others. I think the truth is somewhere in between these two extreme, that is between 3 and 40, and it is still plenty of EROEI. The same is true for the work of De Castro on wind, which I read on TOD, but I found rather poor.

    In any case, the work by Hall and Prieto must be discussed and we need to understand what makes studies theoretically based on the same assumptions provide results that are different for a factor of 10. I am now in Barcelona, working with the Raugei group. One of the things we will be discussing is how to assess this discrepancy.

  16. Ugo, great.

    It would be also interesting to see how much of that growth (hey, NO growth is sustainable) is debt-fueled. It it is largely debt-fueled, expect renewable crunch...

    Nicole Foss has don some good work on this...


  17. Ugo, you are no doubt familiar with the Jevons Paradox, which says that energy efficiency gains, in a typical capitalist political economy of few policy constraints, are used in ways that lead to higher energy use at the macro level. In my view something similar is at work if the “clean” energy alternatives that you are advocating replace fossil fuels to a significant degree. The use of alternatives (again in our dominant form of political economy) will be used to chew up the same resources as fossil fuels do. Many of these resources are nonrenewable, many of them destructive of global carrying capacity in their production and use. As just one example, fossil fuels have permitted an industrialized form of agriculture that is an ecological slow-moving disaster but has temporarily doubled world population, which in turn is causing its own problems. As a systems analyst I am sure you can appreciate the positive feedbacks involved. So in general, significant production of alternative fuels would continue the disastrous process that is producing ‘peak everything’ both in terms of resource depletion and nest fouling.

    Few writers on the subject of energy flow in our planetary system are considering the question: What is the level of energy use (of any sort) that is excessive, because it simply wears out the system. I liken the problem to running a car at rpms that are in the red zone of the car’s tachometer. Again, as a systems analyst I would think that you would be interested in such questions.

  18. Karl, I commented on your points as a complete post on Cassandra. Thanks for the input!