This group brings together the best thinkers on energy and climate. Join us for smart, insightful posts and conversations about where the energy industry is and where it is going.


The Renewable Energy Reality Check

Schalk Cloete's picture
Research Scientist Independent

My work on the Energy Collective is focused on the great 21st century sustainability challenge: quadrupling the size of the global economy, while reducing CO2 emissions to zero. I seek to...

  • Member since 2018
  • 1,007 items added with 397,193 views
  • May 23, 2013
Renewable energy is ideologically very attractive. After all, who would not want clean and “free” energy for everyone forever? Such ideological perfection can easily switch off the critical thinking of environmentally conscious individuals and this is exactly what we are seeing at the moment. This article will therefore attempt to reactivate some of that critical thinking.

Minimal impact on climate change

The first point to be made is that the chances of renewable energy being deployed at a rate sufficiently high to have a meaningful impact on climate change are slim to none. Leading energy authorities such as the IEA, BP, the EIA and Exxon all agree that renewable energy other than hydro will probably contribute about 5% of the global energy mix by 2035. By that time, atmospheric CO2 concentrations will already be well past 450 ppm.

Even if all of these energy experts are off by 100% and renewable energy sources like solar, wind and biofuels contribute 10% of global energy by 2035, global CO2 emissions will still be increasing, rapidly driving atmospheric concentrations towards 550 ppm and beyond. Decarbonizing the energy sector by other means (e.g. CCS and nuclear) will be much more effective.

The logical purpose of renewable energy is long-term energy security through serious market-driven deployment probably starting somewhere in the second half of this century. Continuing current attempts to combat climate change in the slowest, least practical and most expensive way possible (the heavily subsidized deployment of currently available renewable energy technology) is sure to do much more harm than good in the long run.

The price of intermittency

It is very convenient for renewable energy advocates to simply neglect the potentially very large costs associated with the intermittency of renewable energy. As a result of climate variability, the output from technologies like wind and solar varies substantially over a wide range of timescales – minutes, hours, days, weeks, months, years and even decades. Accommodating this wide range of variations will require a wide range of additional infrastructure from the following categories:

  • Fossil fuel power stations operating at low efficiency and low capacity factors.
  • A large renewable energy overcapacity with unwanted energy spikes being grounded.
  • A wide range of material and energy-intensive storage mechanisms which also involve substantial energy losses in the conversion process.
  • Technically, economically and politically complex international HVDC supergrids capable of distributing energy from wherever the sun is shining and the wind is blowing.

Currently, there is insufficient information available to accurately estimate the costs associated with the intermittency of renewable energy, but current storage technology can give some rough indication. Adding battery packs capable of smoothing daily variations will roughly double the price of domestic solar PV, while chemical storage options capable of smoothing out longer-term variations lose about half of the original energy in the conversion process. It is possible that battery prices fall over coming decades (although they may also rise due to material shortages and waste processing regulations), but the efficiencies of chemical storage cannot be improved much further. Thus, it can be estimated that a storage dominated solution will cost at least as much per Watt installed as current solar PV and most probably more.

Insufficient energy return

The third point is related to Energy Return on Investment (EROI). A highly complex society (such as the developed world) where the vast majority of energy is used for a myriad of purposes other than energy harvesting places very high demands on the quality of energy resources. EROI expert, Charles Hall, estimates that we need an EROI of about 10:1 to maintain current societal complexity (click image for source).

Solar and wind have an EROI of about 7:1 and 18:1 respectively, but this is before the effect of intermittency is accounted for. When 4 hours of battery storage is added to solar PV, the EROI drops to just over 2:1 (additional energy costs of panel installation and extra distribution losses are also included). This kind of EROI cannot even sustain the most basic of civilizations, which is a problem because we will need a very advanced civilization to make high-tech renewable energy work. This simply implies that we still require decades of basic RD&D before renewable energy hopefully reaches the point where it can realistically support our civilization.

The externality misconception

Finally, we have to look at externalities – one of the favourite words of renewable energy advocates. Yes, it is true that, at current penetration rates (87% fossil fuels and 1.5% renewables other than hydro), the negative externalities of fossil fuels are larger than those of renewables. A comprehensive EU review study produced the following median estimates in 2006 Euro cents per kWh:




















If, however. through some magical worldwide renewable energy mobilization, the number of solar panels and wind turbines was rapidly increased by a factor of 100, energy storage superstructures sprouted up everywhere and thousands of HVDC cables criss-crossed the countryside in 70 m wide cleared channels, renewable energy would suddenly appear much less green. Vast chunks of nature would be impacted by renewable energy infrastructure, the hazards of rare earth mining would rival those of coal today and e-wastes from decommissioned panels, batteries and turbines would be a major concern.

In parallel, the externalities of fossil fuels would shrink substantially. Air pollution would fall below danger levels, fossil fuel extraction would become safer and less environmentally destructive as lower quality resources are abandoned, and CO2 emissions would fall below the rate at which they are absorbed by the Earth. In fact, it is highly likely that, by the time renewables finally supply the majority of our energy, we will realize that the negative externalities of renewables are now greater than those of fossil fuels.

But the most important negative impact of such an explosive renewable energy expansion would be a rapid rise in energy prices and, with it, a rapid rise in the price of virtually everything else. The primary positive externality of fossil fuels (which is almost never acknowledged) is that cheap and abundant fossil energy with its highly convenient built-in concentrated energy storage neatly packaged in solid, liquid and gaseous forms facilitated virtually every innovation that has brought the great increases in standard of living and life expectancy enjoyed by everyone reading this text. Removing fossil fuels before we have viable alternatives will reverse this externality to the great detriment of society.

The sustained exponential growth fantasy

Despite these arguments, however, renewable energy advocates will probably still believe that renewable energy deployment can somehow continue growing at 20% p.a. for the next four decades, ultimately granting us a paradise of clean and “free” energy where the friendly robots of the year 2050 install solar panels at a rate 1000 times that we manage today. The next post will specifically target this misconception with a detailed look at the law of receding horizons: the tendency of renewable energy deployment to become progressively more difficult as the total installed capacity increases. 

Schalk Cloete's picture
Thank Schalk for the Post!
Energy Central contributors share their experience and insights for the benefit of other Members (like you). Please show them your appreciation by leaving a comment, 'liking' this post, or following this Member.
More posts from this member
Spell checking: Press the CTRL or COMMAND key then click on the underlined misspelled word.
John Miller's picture
John Miller on May 23, 2013

Schalk, very good post.  As you state, many organizations and individuals generally believe that by aggressively supporting renewables and/or discouraging fossil fuels (and most often nuclear) that the world will more rapidly make the transition to non-fossil fuels energy sources and stabilize atmospheric carbon dioxide concentrations at acceptable levels.  Assuming the needed technology improvements become a reality to rapidly and substantially increase the penetration of lower energy density and variable/non-dispatchable power generation in the near future, the primary barrier will continue to be increased energy costs.  Besides increasing the cost of all consumer goods & services in Developed (Annex 1) countries, these economic impacts will very likely accelerate the consumption of cheaper fossil fuels in Developing (non-Annex) countries (with or without carbon leakage considerations).

Another renewable energy reality is that generally only richer Developed countries are capable of making significant transitions to lower carbon and non-fossil fuel energy sources.  Developing countries fossil fuels consumption and associated carbon emissions are projected to increase at rates far greater than Developed countries can feasibly contain or reduce theirs.  Refer to my past TheEnergyCollective post “Can Developed Countries Reduce Future Total World Carbon Emissions”;  (based on the EIA IEO 2011).  Even if Developed countries totally replace all fossil fuels with zero carbon alternatives, world total carbon emissions and atmospheric carbon dioxide concentrations are still likely to increase up to 500+ ppm levels.  Can Developed countries in addition afford to support all Developing countries’ transitions from fossil fuels to renewables?

John NIchols's picture
John NIchols on May 24, 2013

The author is correct. Renewable energy can not power a modern industrial society, even with dramatic environmental degradation.

What he fails to understand is the goal of renewable energy ideologues is not about workable energy solutions.  Rather, their goal is to make society “sustainable”.  To accomplish their objective, adherents feel the society must accept a lower standard of living. This is why proponents push “demand reduction” to hide the failure to build reliable generation.  This is not a formula for prosperity or good health.


Paul O's picture
Paul O on May 24, 2013

Here is what I take from you post:

We can’t rationally get rid of all FFs without a compatible and available substitute. Renewables without storage are a fantasy, and we  probably don’t have the raw materials to support massive renewables deployment with accompanying storage, nor would we be comfortably able to dispose of the waste from such deployment.

I agree.

With these obvious facts, I’ll rephrase what I said elsewhere on this site. The renewables Enthusiasts are going to spend us into ruin and still not make a dent in the world energy and GW problem, and the current energy debate from them is less about Logic, and more about Ideology and Dogma.


Will eagerly await your next post.

Nathan Wilson's picture
Nathan Wilson on May 24, 2013

Good job summarizing the issues.  One that you missed, is hinted at by this, “…we still require decades of basic RD&D before renewable energy hopefully reaches the point …”.

A fundamental pillar of the renewable ideology is that with enough R & D, we can make breakthroughs happen were ever we want them.  Many people truely believe that we’ll start by making solar power affordable in the daytime in the desert, and inevitably conquor the nighttime/cloudy location problem as well.

People in the sciences realize we can’t predict or control where the breakthoughs will happen (with the possible except of computer technology).  We still cannot cure the common cold or make anti-gravity boots or make a safe weight loss pill.  In technology inovation, we first generate solutions using the available knowledge, then go find the problems that match.

The classic example is that we did not develope the microwave ovens to address shortcomings with older ovens. (it was an accidental discovery in a radar lab).


Schalk Cloete's picture
Schalk Cloete on May 24, 2013

Thanks John. Yes, I also agree with your referenced post. Neglecting developing nations in the energy/climate issue will lead to great errors in thinking. 

Developing nations want what we have in developed nations and, as China continues to demonstrate, the phenomenon of catch-up growth can grant them very rapid progress towards this goal (at least for a while). However, there are at least three good reasons why fossil fuel driven industrialization can never work for the developing world:

  • The scale at which the developing world is industrializing is about one order of magnitude greater than the scale at which the developed world industrialized. 
  • The fossil fuel bell curve is already approaching its zenith whereas it was still in the exponential phase when developed countries industrialized.
  • Climate change is now a serious issue (developed nations did not have to worry about this when they industrialized).

And yes, as you correctly said, developing countries cannot industrialize without cheap fossil fuels. Thinking that we can lift 6 billion people up to western consumption levels on solar panels, wind turbines and biofuels is pure fantasy. 

Schalk Cloete's picture
Schalk Cloete on May 24, 2013

This is an interesting point. I’m actually one of those people who think that per-capita consumption (at least in the developed world) will have to fall significantly over coming decades. In fact, this is already happening. In the US, if you look behind the waterfall of cheap money propping up GDP numbers, median incomes and wealth, as well as labour-force participation rates have fallen to levels last seen in the early 90’s. Europe is in its seventh straight quarter of economic decline with record unemployment. It is therefore clear that developed world citizens are reducing their consumption whether they like it or not. 

I am positive that our way of life will change substantially over the next few generations, but I also think that we have to give ourselves every chance to make this transition as smoothly and peacefully as possible. Scuttling the economy through the forced deployment of expensive and impractical renewable energy is definitely not the right strategy.

We still have a lot of fossil and nuclear fuels as well as the technology to use these fuels safely. We should not hesitate to deploy these fuels in order to buy ourselves another few decades over which we can make this difficult transition. Rushing this can only end in tears. 

Schalk Cloete's picture
Schalk Cloete on May 24, 2013

I completely agree that ideology is a big driving force behind the deployment of renewables. Another is the easy modular nature of initial renewables deployment. Solar panels can be installed 1 kW at a time while CCS and nuclear must be installed 1000000 kW at a time, making it much more challenging to finance. 

To the electorate, pretty solar panels and wind turbines together with the PR around them appears very attractive. To politicians, the ease of passing a feed-in tariff and reporting impressive sounding double-digit growth rates at almost no expense for the first couple of years is also very attractive. 

Of course the fog lifts when the feed-in tarriff driving this modular deployment has supported an exponential expansion for a good number of years. Germany has now reached this point where consumers pay 100% extra on wholesale power for 13% penetration of wind and solar. It will be interesting to watch how effectively the world wakes up to these realities. 

Schalk Cloete's picture
Schalk Cloete on May 24, 2013

You are right. I did try to pop the word “hopefully” in there to capture my lack of certainty. 

However, one has to maintain a positive disposition about the power of human innovation, especially now that we live in the infomation age. As a researcher, I really appreciate the possibilities brought by almost endless information and know just how much more effectively one can access and disseminate information nowadays than only a decade or so ago. Estimating the actual impact of the information revolution is of course impossible, but I would like to think that it can accelerate our search for viable replacements for fossil fuels. 

I completely agree that this will take time though – some generations in fact. The point is just that we have to give ourselves every chance to make this transition smoothly and peacefully. And to do that, we will have to accept that we are going to burn fossil fuels for many more generations.

However, we also have to accept that we are constrained by the laws of physics on this finite planet of ours. I have been looking for some good theoretical limits to renewable energy for some time now, but it is not easy. I think wind is pretty close to its theoretical optimum at the moment, but solar PV could possibly still go down in price substantially. Organic PV cells look interesting because they have a low energy input, do not use scarce materials and are highly recyclable. Of course, storage might turn out to be the major limiting factor in the end.

Do you have any thoughts on this issue of hard physical limits to renewble energy?

Randy Voges's picture
Randy Voges on May 25, 2013

Do you have any thoughts on this issue of hard physical limits to renewable energy?

I’ll take a stab at that one.  It is important to grasp that the central issue in energy isn’t energy.  It’s power.  Power introduces the time element into the discussion because it is the rate at which energy is produced or consumed.  To put it another way, not only do we want energy, but we want it quickly and precisely.  This is fundamental to why we burn things; it’s the simplest way to get a lot of energy immediately.  In contrast, renewables like wind and solar are limited for the simple reason there isn’t as much energy in a gust of wind or rays of sunlight as there is in a comparable volume of burning gasoline or coal.  When it comes to the electrical grid, this is why wind and solar are classified as energy resources, whereas thermal and nuclear generation are capacity (i.e., power) resources.

Schalk Cloete's picture
Schalk Cloete on May 25, 2013

Thanks Jim, but we have had this OTEC discussion before. Until I see some peer-reviewed papers documenting that an OTEC plant situated 1000 km offshore can deliver useful energy to society at an EROI well north of 5:1, I will have to remain deeply sceptical about the viability of this technology.

The reason for this is simple: in order to maintain our complex society, we need energy sources with an EROI of about 10:1 and, in order to make extremely challenging concepts like deepwater OTEC work, we will need a highly advanced (complex) society. If the EROI of deepwater OTEC is less than 5:1, we can forget about it. 

Schalk Cloete's picture
Schalk Cloete on May 25, 2013

Thanks Randy, but I was looking more for some quantified limits. For example, Prof. David MacKay from Cambridge gives this very interesting talk on the physical land limitations related to renewables, especially in Europe.

The video is long, but Prof. MacKay is an excellent and very engaging speaker with a very interesting message. However, he did not take the intermittency issue into account (which is a very large omission). 

Rick Engebretson's picture
Rick Engebretson on May 25, 2013

Breakthrough renewable energy is likely to materialize very soon, and grow very fast. But it will not likely be from any of the several “conventional wisdom” areas.

First, I think Germany invested wisely in their solar PV industry. Not because the tempered glass/inorganic semiconductor collection method is great. But because they trained a new generation in quantum physics. Quantum Physics is behind most all the great advancements of the late 20th century; from semiconductors, to biochemistry and medicine, to communications.

I worked in a lab that developed some of the first tube computers; heavy stuff. And I still have some of the walk-in coolers from the lab. I worked at a 1970s Bell Telephone facility with more wires going more directions doing more things with relays making more sparks than most appreciate. I’ve had old cars that spewed fumes containing lead and burnt oil. I was aware of desperate hunger.

I think if we look at cellulose as a starting point for fuel/energy production, instead of a finishing point, we can begin a different discussion of renewable energy. Photochemistry, even high temperature chemistry, is quantum physics. And without quantum physicists we flounder. Every where in the world, the CO2/food/water/fuel issue is important. Change can happen like a tsunami.

Randy Voges's picture
Randy Voges on May 25, 2013


Understood.  The hitch is that there won’t be a straightforward answer to your question.  The physical limits are only one part of the picture.  I’m making the point that the operational limits associated with using wind and solar generation are more significant because of the low energy density and variability (in addition to the intermittency) of the “fuel”.  To this point, this is why there are so many studies exploring the maximum penetration level of wind.  To put it another way, it can be interesting to calculate how much land would be needed to install wind turbines and solar panels in order to replicate the amount of power we currently use from thermal generation, but if experience demonstrates that the maximum penetration level is around 30%, it’s a moot point.

Schalk Cloete's picture
Schalk Cloete on May 25, 2013

Thanks Jim, that was actually a very useful thesis which I was not aware of.

Regarding the tar sands, an EROI of 4 is fine for a marginal source of the fuel that is quite literally the lifeblood of the global economy. Of course the world could never run on tar sands alone, but the massive demand for oil combined with the high EROI conventional fossil fuels that still contribute the bulk of our energy means that this marginal source will be exploited, regardless of whether we like it or not. 

Once climate change starts to have consistent and clearly attributable negative effects on a significant portion of the democratic electorate, CCS will be deployed though a similar mechanism. By that time, our energy systems will most probably still be dominated by fossil fuels and CCS will simply be the most practical and fastest way in which the global economy can respond to a sizable carbon price. We are working hard to have second generation CO2 capture technology commercially available by that time which impose an energy penalty of only about 10% for new plants and 20% for retrofits.

With an EROI of 4, OTEC could also be a marginal source in certain ideal locations if market forces demand it. Some island nations for example could get great use out of this technology. However, powering the majority of the world by thousands of OTEC plants situated thousands of kilometers offshore is very difficult to imagine. Again, the more complex the technology, the greater the level of societal development required to make it work and, the greater the level of societal complexity, the greater the demand on energy resource quality. 

Nathan Wilson's picture
Nathan Wilson on May 26, 2013

Worry about “...limits to renewble energy?”  Not me.  I live in the Saudi Arabia of wind (central US).  We just made our first sale of renewable power to the power company in Atlanta (south east US), and we plan to export a lot more energy to the eastern US over the next decade or two (eventually, they’ll probably get smart, and realize that the 30% renewable vision we are peddling requires too much fossil fuel, and switch to nukes instead).

I did appreciate David McKay’s “Without the hot air” (link to his website), and I sympathize with people who don’t enjoy the plentiful renewable energy (and natural gas) that we have in my region of the world.

Paul O's picture
Paul O on May 26, 2013

I started TEC as an OTEC skeptic, but I am now more open minded to it as probably suitable for some parts of the world that  have none ecologically sensitive deep/cold water flora and fauna. I guess I’m saying that there are places where OTEC could make a difference.

Having said the above, I think there are definite limits to OTEC when talking about powering a high energy using first world industrialized society. We in the US won’t likely have enough suitable OTEC sites, or the OTEC plants may become phenominally massiveand expensive (?) in order for OTEC to provide enough energy for the US’s needs.

I do have one last concern regrding OTEC in general. Fundamentally OTEC transfers surface heat to the cooller depth of the oceans. SInce life at the depths have evolved and stabilized at a lower temperature, I have a really hard time believing that the massive heat transfers from the surface to the depths required for any kind of significant large scale OTEC, is not going to wreck Havock on the fauna and flora at the Ocean depths.

If OTEC really  has little to no effect on the Ocean’s ecology, why don’t we then just pipe Hot surface water to the cooler depths directly, and directly aleviate GW, cool the surface with dumb tubes, and simultaneously employ OTEC for power generation?

Ron Wagner's picture
Ron Wagner on May 29, 2013

It is important not to directly compare petroleum to natural gas as a “fossil fuel”. Biogas is totally renewable and solves many waste management problems. Natural gas is continuously produced and easily observable. Just go to a lake and find bubbles coming up. Peat bogs can be tapped also, and methane hydrates are continuously being formed, they make up an estimated volume of natural gas that is ten times that on land. All decaying organic matter forms natural gas.

101+ Useful references on natural gas:

Bill Storage's picture
Bill Storage on May 30, 2013

Very fine and rare bit of eco-pragmatism. In one comment you say that solar panels can be installed 1 kW at a time while nuclear must be installed 1000000 kW at a time, making it challenging to finance. Would the use of small reactor technology ( < 300 MWe) offer considerable relief on that front?

Schalk Cloete's picture
Schalk Cloete on Jun 1, 2013

I think it could, but you have to remember that, while people generally love wind turbines and solar panels, they are scared of nuclear reactors. Thus, even though small reactors could enhance safety, I doubt whether it will do much to change public opinion. Small scale deployment will probably also have unfavourable effects on reactor economics. 

Stephen Nielsen's picture
Stephen Nielsen on Jul 18, 2013

So, if solar energy somehow allowed us the ability to  “burn things”, it would be a good power fit, right?

Please read up on the coincidental solar revolutions occuring in solar fuel catalysis and artificial photosynthesis. These are allowing and increasingly will allow for the entirely automated creation of fuels and chemical products using only the power of the sun and solid state advanced engineered materials.

Get Published - Build a Following

The Energy Central Power Industry Network is based on one core idea - power industry professionals helping each other and advancing the industry by sharing and learning from each other.

If you have an experience or insight to share or have learned something from a conference or seminar, your peers and colleagues on Energy Central want to hear about it. It's also easy to share a link to an article you've liked or an industry resource that you think would be helpful.

                 Learn more about posting on Energy Central »