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Why We Need CCS, Part 1: The Basics


  • CCS is often neglected as a low-carbon energy option next to renewables and nuclear.
  • Despite its lack of ideological attractiveness, CCS has competitive economics and very broad deployment possibilities.
  • CCS is very well suited to the likely climate change policy scenario of delayed/ineffective proactive action followed by rapid reactive decarbonization.


This five-part article will outline the primary reasons why CO2 capture and storage (CCS) should form an important part of the global energy mix over the 21st century. In contrast to most advocacy pieces, however, no arguments for technology-forcing policies such as feed-in tariffs or deployment mandates will be presented. Instead, the following articles will strive only to illustrate why CCS will do well in what I view to be the most likely future climate change policy development scenario: delayed/ineffective proactive action followed by a somewhat desperate reactive scramble towards rapid decarbonization. The only policy action advocated will be continuation of the funding support necessary to ensure the commercial readiness of efficient second generation CCS technology by the time the reactive climate change mitigation scramble commences.

Why write these articles?

Most people regularly participating in the energy and climate discussion will probably agree that CCS is something of a neglected child in the clean energy family. It does not have the great ideological appeal of renewable energy or the great fundamental potential of nuclear. In fact, most people just view it as a more expensive version of the same old dirty fossil fuels that still power close to 90% of our society. That is why you will find countless renewable energy enthusiasts, a healthy number of nuclear enthusiasts, but almost no CCS enthusiasts.

To try and bring some objective balance to the discussion, this article will make the basic case for CCS. But first, if you do not agree with the scientific consensus that climate change is 1) real, 2) caused primarily by anthropogenic greenhouse gas emissions and 3) potentially devastating in the long run, you are wasting your time with this article. If climate change is not a factor, CCS makes very little sense.


As shown below, the economics of currently commercially available CCS technology compares favourably with other low-carbon energy technologies. For example, a CO2 price of about $40/ton will be necessary to make CCS economically feasible for a significant number of coal plants. Nuclear and onshore wind are the only highly scalable technologies capable of abating CO2 at lower costs. However, as discussed previously, it is highly misleading to directly compare intermittent renewable energy such as wind to dispatchable energy such as coal with CCS.

CCS cost comparison

In its very recent report, the IPCC also conducted a thorough literature review to find the cost ranges of different electricity generation technologies. As shown in the figure below, both gas and coal-fired CCS are broadly competitive against alternative low-carbon options. In addition, it must be pointed out that, in the regions where the majority of global coal is burnt and where the vast majority of new capacity is planned (China and India), costs fall on the left-most edge of the bars below. For example, coal-fired electricity costs less than $40/MWh in China. In addition, the average global capacity factors for wind and solar calculted from BP statistics currently correspond very closely to the “low full-load hours” cases in the figure below: 13.7% for solar and 20.5% for onshore wind.

The cost of CCS also depends greatly on the type of process involved. Capturing CO2 from gas-fired power plants is expensive because the CO2 in the flue gas of a gas plant is very dilute. The situation becomes better for coal, but there are many industrial processes that yield flue-gas streams containing higher concentrations of CO2 (thereby allowing for cheaper CO2 capture). In fact, the IEA sees about half of the CCS deployment up to 2050 happening in industries other than power production.

In addition, there are also mechanisms for the profitable use of pure CO2 such as enhanced oil recovery and various industrial applications. The figure below shows the impact of enhanced oil recovery (EOR) on three different power production technologies: natural gas combined cycle (NGCC), pulverized coal (PC) and integrated gasification combined cycle (IGCC).

CCS with EOR

Finally, just like proponents of other clean energy technologies will undoubtedly claim that technology will yield very impressive price drops in the not-too-distant future, this claim can also be made for CCS. Second generation CO2 capture technology currently in the demonstration stage promises concentrated and compressed CO2 streams for as little as $10/ton in new plants and $30/ton in retrofits. CO2 transport and storage are typically smaller components of the total cost and will initially have negative costs due to CO2 utilization (e.g. EOR). The graph below shows that the US and China can store about 800 Mt of CO2 per year at negative prices – about 5% of total emissions.

Dahowski - Cumulative annual CO2 storage cost curve US China

In fact, a broad deployment of currently available commercial CO2 capture technology is not recommended because it is still rather inefficient (large energy penalty) and potentially hazardous (amine emissions).  A good policy recommendation would therefore be to actively support demonstration projects of second generation capture technology as well as integrated projects demonstrating the full CCS value chain with the sole purpose of ensuring commercial readiness early in the next decade when the first meaningful technology-neutral CO2 abatement policy is expected.

Broad CO2 abatement

When it comes to effective CO2 abatement, CCS has a number of important advantages over nuclear and renewables. Firstly, CCS is the only possible option for meaningful abatements from industry in the medium term. As shown below, industry is responsible for almost 30% of our total energy consumption, making this a very important advantage.

Global primary energy demand by sector

CCS also has some attractive advantages when it comes to the sector consuming the most primary energy (power production). The most important of these is the ability to retrofit existing plants. Power plants typically have very long operational lifetimes (there is a good deal of 50-year-old plants still in operation today) and, without CCS, we have no way of abating CO2 emissions from these existing plants. This is a serious problem because about 1400 GW of new coal-fired power plants is currently being planned to support rapid economic growth in the developing world – enough capacity to lock in about a decade’s worth of CO2 emissions at current rates.

When it comes to new power plants, Chemical Looping Combustion technology capable of very high CO2 capture efficiencies with almost no energy penalty will also be able to stand its ground in an open market with a fair price on CO2. As outlined in numerous previous posts, there are serious question marks about the prospects of solar and wind energy beyond penetration levels of about 10% where intermittency becomes a serious concern. Nuclear, on the other hand, will be able to compete head-to-head with new CCS and it will be very interesting to see how this competition pans out. Another interesting prospect is biomatter power plants with CCS. The carbon-negative power generation capabilities of this technology will be discussed in a later part of this series.

Lastly, we come to transport – the sector where CO2 abatement will probably be the most challenging. Many people still entertain the fantasy of an entire fleet of electric or hydrogen vehicles powered exclusively by renewable energy, but the chance of this happening within the timeframes specified by climate science is essentially 0%. Biofuels offer another option, but have a limited total technical potential and CO2 emissions comparable to that of gasoline (due to the large amount of fossil fuels required in the production process and indirect land-use change impacts). CCS can also play a role by producing low-carbon fuels (e.g. hydrogen or ammonia) from fossil fuels, but this is also a longer-term proposition. We can therefore count ourselves lucky that transport represents only 18% of the total primary energy consumption and still has lots of headroom for efficiency improvements.

Delayed climate action

We humans are very good at postponing potentially unpleasant responsibilities for as long as possible before finally doing what needs to be done and it appears unlikely that climate change mitigation will be any different. As shown below, all mainstream energy roadmaps (IEABP & the EIA) project CO2 pathways that result in long-term atmospheric concentrations in excess of 650 ppm – a scenario which may very well trigger a range of potentially catastrophic positive feedback loops. Even the peak-oil scenario considered by the Energy Watch Group (EWG) significantly overshoots the 450 ppm pathway. If economic growth can be maintained against headwinds such as rising energy costs, excessive debt, aging populations and rising inequality, I have to agree that such a runaway climate change scenario appears to have an uncomfortably high likelihood of actually playing out.

CO2 pathways IEA BP EIA EWG

Indeed, if climate science is correct, it is quite probable that we will reach a point within the next decade or two where the average man on the street starts to experience direct and clearly attributable negative effects from climate change. This will result in a marked increase in the public willingness to pay for deep and rapid CO2 cuts. If this scenario comes to pass, it is quite possible that CCS emerges as the primary CO2 abatement strategy, primarily due to the ability to abate emissions from industry and existing power plants. Nuclear and renewables will also play a role, but will be restricted to new power plants (where CCS could also be an important player).

In short, if the world ever decides to limit atmospheric CO2 concentrations to 450 ppm or even 550 ppm, I can see no viable path which does not involve lots and lots of CCS. Yes, CCS may not be the sexiest energy technology out there, but it may very well be our best chance at preventing very serious long-term climate change damages.

The next article will take a closer look at the likely behaviour of CCS in the strong technology-neutral CO2 abatement policy environment that should emerge under a global push for rapid decarbonization starting early in the next decade.

Schalk Cloete's picture

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Robert Bernal's picture
Robert Bernal on Feb 18, 2014 3:40 pm GMT

Ideally, I’m against it primarily because I’m afraid it will leak back into the biosphere within a very short (geologic) timespan. However, I realize that this will probably get much more development than the intrinsically less expensive approaches to fossil free power (generation) such as closed cycle nuclear.

If only it could be sequestered in a mineral format (for cheap)!

Nathan Wilson's picture
Nathan Wilson on Feb 19, 2014 3:55 am GMT

The cost of solar is changing fast enough that I think it makes sense to always cite a source and date whenever solar cost is reported.  For example, the US gov’s EIA’s 2013 report shows that solar PV is now cheaper in the US than solar thermal or off-shore wind.  The cost plot in this article seems to have come from a 2012 summary of a 2011 report, based on data from who-know-how old.

Nathan Wilson's picture
Nathan Wilson on Feb 19, 2014 4:13 am GMT

It is truly remarkable (and worrisome) how little public support CCS is getting, given how much support it seems to be getting from experts.  The linked Global CCS Institute report says “CCS is the only technology currently available or on the horizon (later this century) that can decarbonise sectors such as cement, or iron and steel.“, and shows this plot from the IEA, with CCS making a large contribution to CO2 emissions reductions:

Kim-Mikael Arima's picture
Kim-Mikael Arima on Feb 19, 2014 6:40 am GMT

No arguments agains your points here, Schalke. However, I’d mirror Mr Bernal below and bring up a comment on the storage part of CCS in a Swedish study. One of the potential challenges of storing CO2 in gas form is that it will remain as dangerous to climate as it ever was. Even spent nuclear fuel rods, so berated by anti-nuke activists, have a half-life. CO2 does not. So I think we need to develop the mineral form storage before CCS can truly contribute.

Bas Gresnigt's picture
Bas Gresnigt on Feb 19, 2014 9:41 am GMT

CO2 storage is not sustainable.
It creates an huge storage problem.

Conversion of CO2 into fuel & gas has more future.

We see now pilot plants coming in Scotland and Germany.


Rick Engebretson's picture
Rick Engebretson on Feb 19, 2014 10:08 am GMT

I agree with your reasoning and intent. But I think you already show the weak part in your first sentence; “global energy mix.” And I think your technology sophistication presents the same problem nuclear presents.

Much of the growing global fuel use bypasses even current pollution control technology. There is desperation in developing energy and even food resources to meet insatiable demand.

And where do skilled workers and stable governments come from to build/operate/maintain these sophisticated technologies such as CCS or nuclear?

I agree continued support for CCS is important. I hope global reason can prevail.

Schalk Cloete's picture
Schalk Cloete on Feb 19, 2014 1:01 pm GMT

Yes, this is a common concern about CCS. The comparison to nuclear waste is a good one and it will be interesting to observe the evolution of public opinion on these issues as climate constraints become increasingly severe over coming years/decades.

About the safety of storage, leakage rates are often given in units like %/millenium, implying very slow, if any leakage. There are several examples of natural underground CO2 stores that have been stable for millions of years and industry already has decades of (successful) experience with storing CO2 for EOR.

In the very long term (timescale of centuries), the global civilization might even consider deploying large stored CO2 reserves as a kind of geoengineering to optimize the biocapacity of the planet. By that time, we should have a much better understanding of the influence of CO2 on the climate and on vegetation growth and should therefore be able to do this responsibly. In this way, large CO2 stores (with no half-life) that can be willingly released or replenished can actually serve a very useful purpose. 


Kim-Mikael Arima's picture
Kim-Mikael Arima on Feb 19, 2014 1:15 pm GMT

I’m afraid that the fact there’s any leakage will make CCS a prime target for activists and massive NUMBYism.  

Very interesting idea regarding long term usefulness of gas form CO2 storages. A bit scifi, perhaps, but interesting. 

Rick Engebretson's picture
Rick Engebretson on Feb 19, 2014 4:12 pm GMT

Interesting Bas. Pure speculation here, but about 10 years ago I had some lunches with Physics Prof. John Broadhurst, at the University of Minnesota. He is from Birmingham, England, his wife from Germany. Prof. Broadurst got his Ph.D. in coal processing but became a nuclear advocate. So now I see the U of Minnesota, Scotland, and Germany talking solar fuel.

My dumb trick was to copy how fire breaks down wood (cellulose) using high energy solar photons. As we spoke his physics talent and enthusiasm assured the notion would grow. It was also an effort to bring physicists into renewable fuels, instead of just farmers. The guy knew more than me in a nanosecond.

Schalk Cloete's picture
Schalk Cloete on Feb 19, 2014 5:27 pm GMT

The scale issue you mention is a very important point. Renewables get much support than CCS for two primary reasons: ideological attractiveness and the modular deployment nature. PV can be deployed 1 kW at a time, while CCS is best deployed 1 GW at a time. This makes technology-forcing policies very convenient for solar PV, but virtually impossible for CCS. 

Schalk Cloete's picture
Schalk Cloete on Feb 19, 2014 5:35 pm GMT

True, CCS will face very similar societal resistance as nuclear, but if the climate problem presses hard enough, society will eventually be forced to let go of this (mostly irrational) resistance. This will probably happen too late for proactive action and the reactive climate change mitigation potential of CCS therefore makes it a very important player in my opinion. 

Hehe… yes, the long-term usefulness of stored CO2 is a bit sci-fi, but it offers an interesting counter-argument to the “no half-life” objection to CO2 storage. 


Schalk Cloete's picture
Schalk Cloete on Feb 19, 2014 5:57 pm GMT

The actual LCOE of solar PV depends on so many factors that the uncertainty range should actually be much greater than that shown in the figure. For some recent perspective, figure 6.16 on page 228 of the most recent IEA world energy outlook projects that solar PV will receive about $1.6 trillion in subsidies from now to 2035 in exchange for about 12000 TWh of electricity – a subsidy of about $133/MWh. Under the optimistic assumption that all this solar PV cleanly displaces natural gas burning at 0.4 tons of CO2 per MWh, the CO2 abatement cost can be estimated as 133/0.4 = $330/ton. 

Ed Dodge's picture
Ed Dodge on Feb 19, 2014 7:57 pm GMT


I agree with your basic points on the importance of CCS, but I would add the importance of finding positive financial incentives, i.e. finding a way to sell the carbon for a profit and convert it into solid materials that will satisfy sequestration requirements.  I reviewed some of these developments in my recent articles here at TEC.

I am skeptical of sequestration underground in saline aquifers because it treats CO2 as a waste disposal problem and leaves unresolved who is going to pay for it.  So far the only successful CCS projects have been for EOR, and it is no coincidence that those projects have a buyer for the CO2.

Converting CO2 into a marketable commodity will induce entrepreneurs to find ever improving methods to capture and transport the carbon.   

The Chinese are moving forward aggressively on CCS.  I quote them below.

In terms of storage, there continues to be a particularly strong focus on using the captured CO2 for commercial applications that may generate a revenue stream. The use of CO2 for enhanced oil recovery (EOR) has been practiced in China since 2006 and the majority of the proposed LSIPs are considering EOR as their preferred storage option. There are also two PCC pilot projects currently in operation which sells food-grade CO2 for food and beverage production.

Robert Bernal's picture
Robert Bernal on Feb 20, 2014 3:38 pm GMT

Thanks for pointing that out, that most of it would eventually be converted into a mineral form.

This is what people (such as I) need to be educated on.

Kim-Mikael Arima's picture
Kim-Mikael Arima on Feb 21, 2014 10:55 am GMT

Thanks, Todd, this was very informative. I can imagine this is not an easy part of the story to get across to the wider audience. 

Clayton Handleman's picture
Clayton Handleman on Feb 22, 2014 7:09 pm GMT

Schalk, I think you have a serious blind spot here.  Solar gets significant subsidies because it is an immature industry and the subsidies drive the industry to maturity and drive down costs. 

Renewables are dropping in cost steadily and since all scenarios being talked about on these pages are save-the-world scenarios it makes no sense to look through a lense of the present or even 5 years from now.  The appropriate lense is 10 to 30 years.  Solar is expected to drop by a factor of roughly 3 in 10 years.  At 10% – 20% penetrations it can make a meaningful contribution to a diverse energy mix.  The appropriate question to be asking about solar is not what has it cost us to date.  Most informed folks are not advocating subsidies for solar capacity, but rather to drive it down the experience curve and purchase cost reduction.  So if you want to make statements about the cost of carbon reduction purchased by subsidies, you need to look at it roughly 15 years out when we have a mature solar industry.  Since PV capacity is growing exponentially and costs continue to drop rapidly the picture will be much different.  And your portrayal of the last year as being all about margin erosion is silly.  While true over that time period, it is not representative of the industry picture over a decade.  After all, it was only a few years ago that margins were exaggerated due to supply constraints, so a lot of the margin erosion was just bringing things back into line with reasonable profits.  Your graph and suggestion that margin erosion is representative of the big picture and potential for cost reduction is solar was, to be charitable, myopic.

Wind power will continue to expand in the US Great Plains, increasing capacity factor and lowering the cost of wind power.  As transmission is added, as is happening in Texas and Kansas, higher CF sites will be accessed and the volume will be sufficient to drive wind power further down the learning curve.  For example, the average hub height in the Great Plains is 80m and the average CF is 37% for non-optimally sited wind farms.  Vast improvements in CF accrue as we move to higher hub heights of even an additional 20 meters.  Also, turbine heights continue to advance roughly doubling every decade.  This relentless advance is providing access to higher CFs even in lower wind areas such as Germany with hub heights of 140m.  Of course increased CF substantially reduces the negatives of wind power.  It improves transmission line utilization and reduces storage and backup requirements.  If the US gets smart and uses your number of $40 / MWhr or even half of that to penalize coal then it is game over, wind economics get ridiculously compelling.

You make prognostications about what the cost of CCS will be in 10 years but you seem to hold renewables to a different standard, for example suggesting that the current 37% CF in the great plains may be as good as it gets (paraphrasing an earlier exchange you and I had).  You reject the notion that storage will come down in cost rapidly and don’t even consider the 10 year planning horizon for batteries, let alone a more relevant 20 year scenario.  It looks like lithium Ion batteries may surprise and become a viable contender for bulk storage.  The cost of this technology is expected to continue its precipitous drop over the next decade and that is as far as the analysts are projecting these days.  Initially this likely will occur through V2G for moderate renewables penetration.  In the 2 to 3 decade time frame, EV batteries that are no longer suitable for cars will be repurposed for bulk storage before being recycled.  This will provide a very low cost solution for bulk storage.  And this is a worst case scenario, many expect flow batteries to be much lower cost than Lithium Ion.  

While one can argue with the case I have made, I will point out that it is primarily based upon commercially available technologies with established trends.  Your ongoing contention is to ignore those trends or pretend like they will stall in 5 years or cannot be relied upon.  Yet you suggest that untested CCS will magically sail through successfully exactly as projected by its advocates and we all should wait 10 years for it to magically appear and solve the problems. No hickups and no surprises.  That would be unprecidented and I think very unlikely.

So I ask, who is the “activist” and who is the advocate.  Your ongoing labeling, as activists, those who advocate renewables, calls into question your self proclaimed objectivity. 

Honestly, I love the amount of information you bring to the conversation and that you back up your position with referenced material.  And I am very happy to see you publishing you long overdue pieces on CCS, your area of expertise.  However, I hope you will dial back the rhetoric suggesting that renewable energy positions must be ideologically driven and that people whose informed position is to favor renewables must be activists.  It certainly undermines your claim to objectivity.




Schalk Cloete's picture
Schalk Cloete on Feb 22, 2014 9:03 pm GMT

We have had this conversation many times before, so I will not repeat myself on the finer details.

The central point remains that renewable energy technology-forcing remains the slowest and most expensive CO2 mitigation mechanism. This is an incredibly important point because billions of developing world citizens are flocking to megacities in an unpreceded push towards fossil fuelled industrialization – something which is absolutely imperative when it comes to stabalizing the global population, the first prerequisite for long-term sustainability. This industrialization simply cannot happen through expensive, capital-intensive and intermittent wind and solar power which abates CO2 for 17 times the cost of market-driven alternatives. More details can be found in a previous article.

In practice, it is the ideological attractiveness of wind turbines and (especially) solar panels that secure the public support necessary to continue ramping up already very large subsidies. A few comments down from this one, I again calculate that, according to IEA projections, solar will receive subsidies equating to about $330/ton of CO2 avoided over the next two decades. Before you respond to this, please just reread my reply to you five posts up from the bottom of this page.

The point of this particular article is that CCS is especially suited to the reactive climate change policy environment that is likely to emerge over coming decades. Since CCS is capable of abating locked in emissions, it is valid to consider longer-term costs per unit CO2 avoided. For solar power, on the other hand, expensive installations done today will remain expensive until the long-term FiT deal runs out.  

Robert Bernal's picture
Robert Bernal on Feb 23, 2014 12:55 am GMT

Conversion of CO2 into more fuel is like reducing emissions by only a small amout… it still takes energy and thus more emissions, except in the case where closed cycle nuclear is used for the high process heat required to make liquid fuels. What we really need to do is mass produce lots of electric car batteries. They get like thousands of charges, make the original electric source almost 4x as efficient AND can be recycled.

Perhaps, it is time to accept a few CCS projects, wait a decade and see if it really does not leak back into the water supply.

Of course, in the meantime, we need to develop the least expensive non fossil source and fire all the excess regulators which seek to profit from F E A R. (They cause big solar and wind to cost more, too!).

Forever Eliminate Advanced Reactors?

Clayton Handleman's picture
Clayton Handleman on Feb 23, 2014 4:16 pm GMT

“This industrialization simply cannot happen through expensive, capital-intensive and intermittent wind and solar power which abates CO2 for 17 times the cost of market-driven alternatives”

I am not finding the 17x number you are referring to.  Does it reference wind, solar or the combination of the two.  And is it based upon today’s prices or projected prices.  If so, when. 

My experience of your posts is that you use these figures somewhat interchangeably.  I am trying to at least understand your quantitative position at a baseline so here are a few simple questions:

What do you think the $/kwhr will be for solar 10 years from now.  I am fine if you want to include needed storage.

Same question for wind?

You indicate that the target number for solar to be cost effective is $0.31 / W and that takes into account storage.  Presumably you have a similar figure for wind.  Since wind has a higher CF, what is your number for $/W installed for wind?


Assuming business as usual, what is the cumulative cost in R&D for CCS from now until this tipping point that you are suggesting will occur in about 10 years in order to assure that it is ready to deploy on a commercial scale?

What percentage of that do you envision being spent by governments and what percentage by the mature fossil fuel industry?



Clayton Handleman's picture
Clayton Handleman on Feb 24, 2014 12:12 am GMT


I was noticing that Nathan had done this and wondered how he did it.  If it is easy, would love to know how you did it.

I think part of the reason we have talked past each other somewhat is that my focus is the US and you seem to be mostly using Europe to base your projections.  I am hoping that the US will do some heavy lifting driving volume of wind and driving it down two more cumulative doublings on the experience curve.  I think this is quite likely if we can garner the wherewithal to build HVDC transmission out to the interior states from the East Coast.  For solar we can help some as well through SunShot and driving out soft costs but looks like China and India will be driving the volume.  At the end of the day, I agree that Solar is not the solution, only a contributor. 

From other postings you have put out I think we agree that as CF of wind pushes into the high 40’s and low 50’s it is just not the same animal as that which is the norm today.  Even more so when done over 1000 miles of separation to decorrelate the sources.  The capacity credits can be much higher than anything we have today. And (spoiler alert) I think there is a pretty compelling path to get to a lot of landbased 50% CF wind in the US. I reviewed some of your earlier comments and noticed that you are skeptical about going beyond the current 37%.  I completed one piece that TEC did not publish and have another one in the works that shows my thinking on this.  I hope I will find the time to complete it and TEC will see fit to publish it as it is germain to a number of threads.  In any event I will make it available to you either way and hope you will view it with an open mind.  I think we come from very different backgrounds, yours appears to be more R&D and academic, mine has a good bit of product development and manufacturing included so I have a good deal of confidence in the power of Experience curves to disrupt technology.

Its also worth pointing out that Europe may not yet be played out in terms of CF.  With Enercon’s E-126 and the new GE Turbine are 135m and 139m hub heights respectively there may be some new life breathed into that market in terms of improvements.  I will try to scare up some time to read your post on the Hirth paper, presumably they took into account factors such as tech advances, though I don’t think the GE turbine was out yet, certainly the Enercon one was.

As you point out, storage is relatively cheap for low penetration renewables.  The question is how much it will come down in cost as volume increases.  The EV industry could completely change that calculus.  Likewise, if R&D is well funded there are promising technologies. 

I am looking forward to your upcoming posts on CCS and gaining isights into the status of that technology.  Some treat it as a done deal, as if it is ready for prime time now.  Is it?  If not, what provides the confidence that it, like so many other new technologies is not likely to suffer set backs and learning curve pain?


Nathan Wilson's picture
Nathan Wilson on Feb 24, 2014 5:05 am GMT

The method I use to insert images into comments is to first click on the “Input format” drop-down menue below the text box, then select “Full HTML” (sometimes the “Input format” option is not visible, but if I submit the comment, then select “edit” it always seems to appears for me).  In Full HTML, the toolbar above the text box has an icon with a tree on it, that’s the “insert/edit image” button (it can only take urls, no file uploads).

Nathan Wilson's picture
Nathan Wilson on Feb 24, 2014 5:42 am GMT

Just to briefly summarize the other side of the discussion from previous threads:

  • Certainly taller towers provides access to higher average wind speeds.  This does not mean that the variation in wind speed is reduced.  (unless you’re up in the jet stream, above the weather).
  • Absent a reduction in variation of windspeed, higher average windspeed does not imply higher capacity factor.
  • Windfarm designers seek to choose the most economical combination of tower height, blade length, and generator size.  Making the generator smaller would push up capacity factor, because it would max-out at a lower windspeed (blades must get feathered at higher speeds to avoid over-powering the generator), but would produce less average power than a larger generator.
  • On storage, lead-acid batteries cost about $0.20/Watt-hour, which is super-low.  If lithium-ion batteries fall to this level, then electric cars are likely to take the majority of the car market.
  • Used batteries will cost less than new ones, but they will have higher handling cost and shorter life, so it is not clear they are more economical.
  • For $0.20/Watt-hour, a 15 hour battery for solar PV smoothing would cost $3/Watt and (if it had much longer life than lead-acid cells) it would be useful in desert climates, but only if PV were really cheap.
  • For northern climates, adding storage to PV only results in a capacity factor of 50% or so (due to cloudy/short days), and it does not correlate with demand peaks (which happen in the winter), so a need for balancing with fossil fuel fired generation will remain.
  • For smoothing wind power in most locations, 10-20 hours of storage does not help much, so a need for balancing with fossil fuel fired generation will remain.
  • Ammonia, which is a fertilizer and a carbon-free fuel, is made today from fossil fuel, using CC&S in some location; it is a potentially useful fuel for heavy trucks, electrical peaking, and combined heat & power, none of which is suitable to batteries; ammonia can also be made from nuclear or renewable power for somewhat higher cost.

The continuing need for fossil fuel fired generation in high-renewable scenarios suggests that CCS should be considered in all low-nuclear scenarios.

Clayton Handleman's picture
Clayton Handleman on Feb 24, 2014 6:29 am GMT

Thanks for the tip on formatting. 

“Windfarm designers seek to choose the most economical combination of tower height, blade length, and generator size.  Making the generator smaller would push up capacity factor, because it would max-out at a lower windspeed (blades must get feathered at higher speeds to avoid over-powering the generator), but would produce less average power than a larger generator.”

I agree with what you wrote above.  Not so sure regarding your comment on CF vs height.  See below.  Has this NREL work been shown to be flawed? If not, it is pretty exciting. 

The issue in central US is that there is no transmission access to the best sites.  The question is whether the better sites justify building the tranmission to them.  The numbers are pretty interesting.  I am pretty sure EWITTS was done with 80m data.  Check out below:

Schalk Cloete's picture
Schalk Cloete on Feb 24, 2014 6:31 am GMT

I agree that the US has substantially greater wind and solar potential than most others and would love to see some independent studies published in prestigious peer-reviewd journals following Hirth’s methodology for the US itself. However, the concentrated nature of the good wind (the interior) and solar (the south-west) zones presents a substantial problem. Going to higher penetrations will require enormous country-wide supergrid buildouts. These HVDC lines will carry low-CF wind and solar power thoughout the country, implying a low utilization factor, driving up costs.

US investment in such a massive and complex inter-state infrastructure project will not happen quickly, especially while wind and solar deployment still dependent on PTC, ITC and RPS policies. Even if wind and solar one day become capable of standing alone (when a CO2 price is hopefully implemented), this will still be a struggle due to the high upfront costs, the complexity, NIMBYism, and the fact that some states will win while others lose. Thus, while I agree on the fundamental potential, I think it will take a lot longer than most proponents imagine. 

About CCS, the nice thing is that it isn’t exactly rocket science. You capture the CO2 using relatively simple absorption-desorption processes, you transport it through pipelines which have been used to transport natural gas for many decades, and you store it using techniques perfected by the EOR industry over many decades. Once you have done that, you are left with a source of dispatchable energy that still fits perfectly into our current energy systems (fossil fuels still supply 87% of global energy). The only issue is that, outside of EOR using CO2 captured from a limited number of industrial processes naturally yielding an almost pure CO2 stream, someone has to pay for it. For this simple reason, nothing meaningful will happen in the CCS sphere before we get a high and rising CO2 price.

Clayton Handleman's picture
Clayton Handleman on Feb 24, 2014 6:31 am GMT


Reposting graph at the top so comment is wide enough.

Clayton Handleman's picture
Clayton Handleman on Feb 24, 2014 7:05 am GMT

From comment thread below so that it is wide enough for graph to show up. 


Clayton Handleman's picture
Clayton Handleman on Feb 24, 2014 6:58 am GMT

These guys are attempting to do a project from one of the best areas in the country (see the graph I just posted at the top of the comments).  It is considerably better than any of the areas currently being built on if the NREL maps are to be believed. The reason we are stalled at sub 40% CF is not due to the resource but rather the transmission access. There is a large build out in IN, IL and IA none of which have a comparable wind resource.  It is good, but not as good as this patch of KS.  And Buffalo ridge has only a very small portion that is close to this quality.  Even TX has little transmission access to their highest wind sites and therefore their CFs do not represent the highest available.  I have not found maps of their new transmission projects so don’t know if they will be accessing the best sites or not. 

If the Grain Belt Express (linked to above) is successful I think it will open the door to other similar projects.  There is similarly excellent resource in NE and TX and some other less geographically tight spots in ND and SD.  All have a good deal of 50% CF at 100 meter hub and it appears that higher hub heights will yeild higher CFs.  This appears to me to be a game changer.  The studies like EWITS used lower CFs for their conclusions.  Their wind data was based upon models that were developed prior to the publishing of the High CF 100m hub height data sets. 

Clayton Handleman's picture
Clayton Handleman on Feb 24, 2014 7:02 am GMT

“NIMBYism, and the fact that some states will win while others lose.”

I agree with this and it strikes me as the biggest issue. 

I am still crunching numbers but I think the 50% CF gets pretty close to competitive without subsidies even after paying for transmission as long as it gets to the East Coast where electricity is $30 / MWhr higher in price than in the midwest.

Schalk Cloete's picture
Schalk Cloete on Feb 24, 2014 10:52 pm GMT

I assume that the 100 m turbine is essentially just the 80 m turbine mounted on a taller tower. In this case, it is clear that the greater wind speeds at higher elevations will result in higher capacity factors since the turbine will be running at maximum capacity for a larger percentage of the time. 

Again, this will simply be an economic optimization exercise. Due to the larger leverage created by the force at the top of the taller tower, 100m towers will require larger and deeper foundations and thicker towers than 80 m turbines. In fact, the mass of material required in the foundation and the tower itself will probably scale with the height to the power of three, implying a non-linear escalation of costs with increased tower height. Taller towers also require taller, stronger and more expensive cranes in the construction process and will complicate the transportation of the components. It is therefore clear that there will be a point where taller towers become economically unviable.

Clayton Handleman's picture
Clayton Handleman on Feb 25, 2014 12:59 am GMT


you are right.  Since the mass of the turbine is proportional to roughly the cube of the blade length but the power only to its square, economics will limit that height.  And for years, academics have tried to estimate what that limit will be.  In the mean time, engineers just keep pushing the envelope sending the academics scurrying back to their keyboards scratching their heads and reworking their numbers to reflect the reality they had denied could exist only a short time before.  100m is rapidly becoming the new normal and one could make the case that, for commercially available turbines, it already is.  Enercon has been selling a turbine with a 135m hub height turbine since 2009 and last summer GE introduced a turbine with a 139m hub height.  I think it is pretty safe to say we know how to build economical wind turbines at 100m hub heights. 

Despite the prognosticators pronouncing limits on the ‘possible maximum’ hub heights, they have been roughly doubling every decade and wind turbines have continued down their experience curve lowering the cost of energy generated.  Like solar, there have been pauses in wholesale price decline.  Those, however, have been driven by supply and demand rather than manufacturing costs. 

I think an interesting question is, what is a sensible planning number to use in comparing technologies 10 – 15 years from now.  One thing is for sure, it is higher than 100m.





Nathan Wilson's picture
Nathan Wilson on Feb 25, 2014 5:22 am GMT

I think the above plot is really aimed at showing the difference in wind speed at different locations.  In that sense, I think you can use the capacity factor shown to calculate the difference in wind energy cost from one location to another.  As Skalk mentioned the bigger tower will cost more, so I dont think it’s fair to assume a linear cost relationship for the different heights. (So I believe they have assumed the same wind turbine for both plots, and did not optimize the turbine selection based on wind strength, as would occur in a real wind farm).

As I mentioned, this optimization of the tower height, blade length, and max generator output is done by the wind farm designer.

This product list from GE shows:

  • the 1.5 MW turbine comes with a 77m rotor (2x blade length + hub dia.), with a choice of 65 and 80 meter towers.
  • the 1.6 MW turbine comes with 82.5 or 100 m rotor.
  • the 1.7 MW turbine comes with 100 m rotor.
  • the 1.85 MW turbine comes with 82.5 or 87 m rotor.
  • the 2.5 MW turbine comes with 100 or 120 m rotor, and 85, 100, 110, or 139 m towers.

Generally, GE is recommending the larger rotors and towers for sites with weaker winds, also larger towers are good for forested areas.

To provide some sense of the variability of wind, the following histograms come from Sustainable Energy – without the Hot Air, p. 34, and represent the windspeed distribution for daily (left) and half-hourly (right) for Cambridge.  Obviously wind is stronger in Kansas, but the point is that since a variable speed wind turbine’s output goes with the cube of windspeed, there is a lot of energy in the tail of the distribution, so a more powerful generator can make more energy from the same blades, but with lower capacity faotor.


Again, the reason all of this matters is that given the wind’s variability, the turbine that produces the higher capacity factor at a given site is not necessarily the most cost effective, hence it’s not obvious that capacity factors will rise in general.   This means that we can expect that when fossil fuel is used to balance windpower, the fossil fuel source will continue to provide more energy than the wind farms.

By the way, the Sustainable Energy book shows a plot of wind energy density per unit land area.  The growth in energy density with tower height is modest:  32% going from 100m to 200m.

Bob Meinetz's picture
Bob Meinetz on Feb 25, 2014 3:26 pm GMT

Schalk, CCS has a host of other non-technical problems unrelated to the (significant) potential for fraud we’ve been over many times.

Never in the history of humankind has a government spent huge sums of money, with public support, minus any visible or direct proof it’s accomplishing anything at all. This simple truth is a deal-killer. Though you and I can understand how committing x gigatons to storage will eventually stabilize the climate decades from now, there is no society on earth which will make CCS a priority for that reason alone. To argue that an enlightened populace will rise in support is to argue with thousands of years of history.

I live near the old Lockheed Skunk Works advanced aviation facility in Burbank, CA. Since pre-WWII the factory had been dumping PCBs and vinyl chloride “behind the shed” – tons of it, leading to a monumental pollution problem as those volatile organic compounds seeped into the water table. About twenty years ago there was a public discussion about how to address the contamination: truck it out? Too much toxic dust. Set up smokestacks and burn it off? There would be a few extra cancer cases in the area. What happened was this: it was paved over and a sleek new shopping mall was built smack-dab on top of one of the biggest EPA Superfund sites in the country.

Until CCS meets the same fate as these grand schemes, it serves conveniently as a responsibility shirk, a future tech fix for current abuses, a distraction from what we really need to address: pulling less carbon out of the ground to begin with.

Clayton Handleman's picture
Clayton Handleman on Mar 1, 2014 4:36 pm GMT


This post does a good job of clarifying why I think that there considerable headroom above the current 37% CF in the Great Plains.  Whether the CF number is 55% or 45% I think that even a lay person, armed with the knowledge that power increases with the cube of windspeed*, would have a hard time looking at these maps and concluding anything but that there is a good bit of headroom for the capacity factor. 

Capacity factor and capacity credit play two different but very important roles in the economics.

The capacity factor is quite good for assessing transmission line utilization as the relationship is pretty much linear.  If the transmission line is designed to handle peak load from a group of wind farms then percent utilization = capacity factor.

Capacity credit is considerably more complicated and it goes directly to the amount of backup required.  The analysis is much different for a high wind regime, such as Kansas, than for a low wind regime such as Cambridge. 

In Cambridge, the wind speeds are low.  Therefore the change in capacity credit will be small for a given change in capacity factor.  This is because much of the gain in capacity factor comes from increased energy due to the high windspeed tails of the distribution.  Since power goes as the wind speed cubed the tails will contribute disproporionately.  In other words, in Cambridge, the tails of the distribution curve lie on the nonlinearly increasing part of the turbine power curve.

In Kansas, wind speeds are so high that the tail of the distribution is on the flat part of the turbine power curve.  This means that for much of the tail, increased wind speed does not increase the power at all.  Therefore you get little benefit from increased wind speed at the high end of the distribution.  The bulge in the wind speed distribution is sitting right smack on the nonlinear part of the curve.  Relatively small increases in average wind speed lead to much higher percentages of the wind distribution being productive in energy production.  And more importantly, rapidly diminishes the statistical probability of having wind speeds that are insufficient for the turbine to operate at all.  And it is this last consideration that increases the capacity credit.  This is at the heart of why going from high 30’s to 50% capacity factor has much more significance than from mid 20’s to mid 30’s.  

This paper has wind distribution curves typical of the region.    

Regarding tower height, I looked at the source you provided and they support the notion that taller towers improve turbine economics.  The modest 30% they reference is for land use efficiency.  In the UK that is an issue.  In the central US, particularly in symbiotic use areas such as ranchland in Texas and Nebraska, I am not hearing much concern about efficiency of land use.  Fossil fuel apologists will try to make the case that it will decrease the efficiency of power tranmission, a good qualitative point for sohphistry but negligible in terms of losses.

Here is the rest of the quote that you cited.  Notice that the source you provided agrees that higher wind turbines have the benefit of delivering higher economies of scale. 

“Chapter B explains. Bigger wind turbines deliver financial economies
of scale, but they don’t greatly increase the total power per unit land area,
because bigger windmills have to be spaced further apart. A wind farm
that’s twice as tall will deliver roughly 30% more power.”


Schalk Cloete's picture
Schalk Cloete on Feb 26, 2014 7:11 am GMT

My thesis on the deployment of CCS is a pretty simple one:

1) Fossil fuelled economic growth will be prioritized over climate change as long as climate change has a limited real-world impact, thus leading to an overshoot of climate targets.

2) When real-world climate impacts eventually start to have a large and clearly attributable effect, public opinion will shift rapidly.

3) This shift in public opinion will lead to a rapidly rising CO2 price.

4) A rapidly rising CO2 price will lead to a rapidly rising production (and storage/utilzation) of CO2 through CCS.

5) CCS is very well suited to such a reactive CO2 mitigation scenario due to the ability to access locked-in emissions, abate emissions from industry and because it will be less capital intensive than most alternatives. 

I’m unclear about the timeframes over which this will play out (mostly determined by real-world climate change impacts), but am fairly confident that the lack of proactive action will eventually necessitate such reactive emissions cuts through CCS in spite of the non-technical problems you mention. 

Joris van Dorp's picture
Joris van Dorp on Feb 26, 2014 9:25 pm GMT

Lack of support for CCS seems to be nimby. We tried and failed to get an onshore pilot carbon storage built. The local residents failed to understand the (lack of) risk.

I also think that CCS is a no-brainer. I like Schalk’s articles on the subject. I’m not sure whether it will be easy to do CCS on the very large scale that would be necessary. I am under the impression that you do need geology working with you. You can’t just inject the stuff just anywhere.

Besides CCS, I think nuclear is a no-brainer too. A new report on Fukushima came out, estimating the lifetime dose to the public from future radiation exposure due to the accident. As expected, the dose is really very low. So low that it won’t be detectable in terms of additional cancer among the population.

Just imagine. Due to a catastrophic tsunami, three nuclear reactor cores melted, which killed noone, and which will kill so few people – if any – that it won’t even be detectable epidemiologically! Yet people still think nuclear is unsafe! It’s so absurd that if it was not actually the case, I wouldn’t believe it was even possible. After all more than a million people die every year from fossil fuel polution. Yet nobody fears fossil fuel polution. (Well, some people do, but they’re usually a bit weird, aren’t they?)

Anyway. Nice chart. I expect renewables will keep doing well going forward. I guess they deserve it, barely. As long as people are willing to spend their taxes on it, they’ll do fine. Nuclear – I’m actually starting to worry that it will never really take off. Nuclear is simply too much of a business threat to wind, solar, coal, gas, oil, railroads, and all manner of businesses involved in sustainability. And to top it off, pretty much the only group who will actually benefit greatly from a strong development of nuclear power – the public – is dead set against it. The irony. Reality can be stranger than fiction.

Clayton Handleman's picture
Clayton Handleman on Mar 11, 2014 4:13 am GMT

Those pesky engineers keep finding ways to surprise.  Looks like GE is going back to the lattice tower and covering it for aesthetics and avian mortality.  They seem to think that this will get them more height and the ability to transport towers more easily.  People may go back and forth but I think the writing is on the wall, 100m is a done deal and it is looking like 130 – 150m will be coming in the forseable future to a high wind site near you (already there for class 3 winds).  I imagine that cranes will be the limiting factor before the tower economics but that is just shooting from the hip.

Bas Gresnigt's picture
Bas Gresnigt on Mar 11, 2014 7:20 am GMT

…Bigger wind turbines deliver financial economies of scale, but they don’t greatly increase the total power per unit land area,…
A bigger wind turbine has a bigger rotor diameter, hence catches a bigger vertical column of air.
Which implies also an higher air column with the same tower height.

A turbine with 50m blades and a 125m tower, catches the 100m high column of air between 75-175m.
A turbine with 75m blades and a 125m tower, catches an 150m high column of air between 50 – 200m.

So a wind park with bigger wind turbines will also raise production per m² of the windpark substantially (and of course the land between the towers in the windpark will be used as usual).

Bas Gresnigt's picture
Bas Gresnigt on Mar 11, 2014 8:54 am GMT

The German Energiewende decisions in year 2000, were based on the predictions that the costs of renewable would come down gigantic if a mass market would be created.
Those predictions were supported by many consultancy reports regarding solar, wind, storage, etc.

Without those costs decreases, the Energiewende would have become a gigantic failure. E.g. in 2000 solar did cost >70cent/Kwh, onshore wind ~20cent/KWh in Germany. 

The assumed decrease for geothermal energy didn’t turn out (yet). Mainly because the technology to detect / predict the presence of substantial hot water ~a mile below the surface lags behind.

Assumed moderate cost decreases for biomass stayed low. So the role of biomass will not rise and may decrease greatly.

Similar with pumped storage.
The installed 35 pumped storage facilities are not profitable at the moment. Main reason: the overcapacity of fosssil plants, partly because the electricity savingsplan of the Energiewende is a succes. Another much smaller reason:    
Norway, Austria, Switserland often cut off their hydro production if German electricity is cheap and import German electricity, doing the other way around the moment German electricity is more expensive.
But profitability may improve greatly in ~2025-2030 when the share of renewable is ~50% (predicted by scenario studies) but by then batteries may takeover their role.

Bas Gresnigt's picture
Bas Gresnigt on Mar 11, 2014 9:12 am GMT

CCS is not sustainable technology.

Furthermore, as Joris also noted, most people here in NL do not want to live above a potential CO2 bomb 600m below surface (the natural accident with the lake in Africa that killed all villagers around the lake is wellknown).

So, allthough heavily promoted by government and big chemical companies, the idea is off here in NL. 
Even storing in the North-Sea bottom. But that may change if CO2 prices rise. However that will not happen in the EU for at least the next 4years as Merkel was against.

Bas Gresnigt's picture
Bas Gresnigt on Mar 11, 2014 9:26 am GMT

Nuclear – I’m actually starting to worry that it will never really take off.”
Right. The main reason being the lack of subantial improvements of nuclear since ~1970, while other technologies such as solar, wind, storage made and will make big steps forward leading into a paradigma change in electricity provision.

WHO estimates that 2-7% of children that lived nearby the Fukushima Daiichi nuclear plant, will get cancers, etc…

Bas Gresnigt's picture
Bas Gresnigt on Mar 11, 2014 9:40 am GMT

The target of solar investment is not CO2 abetement, but electricity generation.
Less CO2 is a side effect.

Suggest that you adapt your calculation accordingly.

Robert Bernal's picture
Robert Bernal on Mar 11, 2014 3:07 pm GMT

However, the point is that the “side effect” of less CO2 (by use of solar and subsidy) is more costly than other measures of reducing excess CO2. I could be of the mind to construe it as “why bother if there is another, better way?”, but I know that there is good in solar. Therefore, I would ask for the subsidies to end. That way, the industry would finally be willing to make the parts for cheaper. However (again) we don’t want it to backfire and cause no solar growth, therefore, we should slash all solar subsidy which benifit the current system, and instead, apply “all that” just for the machine development of far less expensive solar.

Only in this way will the “side effect” become far less trivial. If we continue with subsidies as usual, we will have wasted the money on a rather trivial amount of CO2 abatement.

We should also subsidize the coupling of high temp, melt down proof nuclear with gas turbines, if we are to substantually reduce excess CO2. And that’s the whole object, isn’t it?

Clayton Handleman's picture
Clayton Handleman on Mar 11, 2014 3:20 pm GMT

I think people make a mistake in pricing subsidies strictly in terms of $/kwhr for the given array purchased.  Subsidies, with the German program being the most significant, stimulated demand sufficient that investment was made into increasing production which brought the price down.  So there is a dual benefit from demand programs.  The first is the immediate $/kwhr but the more important effect is the reduction in cost of solar.  If the cost of solar did not drop then there would be no secondary benefit.  These plots show how cost decreases predictably through increased volume.  And by subsidizing demand there is incentive for private capital to be brought into play thus leveraging the subsidies.  The $/W should be calculated in terms of a much longer timeframe and looking at the cumulative cost per watt.  In other words, today’s purchase also creates the $1.00 / Watt 10 years from now.

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