"The Emperor's New Clothes" Problem of the Renewables

My last post pointed to what might be called "the Emperor's New Clothes" problem of renewables. When I started looking at energy options in 2007 I was considerably more optimistic about the potential of renewable energy to make an important contribution to carbon mitigation than I am now. In 2007 I began to ask some obvious and straightforward questions about renewables in a post carbon grid. My questions focused on the intermittent of major post-carbon renewables including Solar Photovoltaics, Solar thermal, and onshore and offshore wind generation.

When I asked my questions, I was told that I did not know how the grid works. This provided to be a less than satisfactory answer, because the way the grid worked required the burning of a lot of fossil fuels, that produced far too much CO2. When I pointed this out, I got two sorts of answers:

* A renewable dominated grid can be made reliable by creating transmission links between lots of renewable sources.

* A renewawables dominated grid will depend on a lot of energy storage.

A careful examination of both answers will reveal that they are both seriously flawed. Ten Trainer points out a electrical supply problems wich no ammount of renewable transmission linking will solve.

The greatest challenges set by variability of wind and sun concerns the gaps of several days in a row when there might be no sun or wind energy available across large regions, including continents. Following are cases from the many studies documenting the magnitude and seriousness of these common events.

· Lenzen’s review (2009) includes impressive graphs from Oswald et al, (2008) and Soder et al., (2007). The first shows wind energy availability over the whole of Ireland, UK and Germany for the first 300 hours of 2006, i,.e., in mid winter, the best time of the year for wind energy. For half this time there was almost no wind input in any of these countries, with capacity factors averaging around 6%. For about 120 continuous hours UK capacity averaged about 3%. During this period UK electricity demand reached its peak high for the year, at a point in time when wind input was zero.

· Soder et al. provide a similar plot for West Denmark in mid winter, again one of the best wind regions in the inhabited world. For two periods, one of 2 and one of about 2.5 days, there was no wind input at all, and in all there were about 8 days with almost no contribution from wind energy.

· Lenzen’s third plot is for the whole of Germany, again showing hardly any wind input for several days in a row. (See also E.On Netz, 2004.)

o Davey Coppin (2003) make the same point for Australia with its much more favourable wind resources than Germany, for instance indicating that for 20% of the time a wind system integrated across 1500 km from Adelaide to Brisbane would be operating at under 8% of peak capacity.

· Mackay (2008, p. 189) reports data from Ireland between Oct. 2006 and Feb. 2007, showing a 15 day lull over the whole country. For 5 days output from wind turbines was 5% of capacity and fell to 2% on one day.

· Similar documentation on lengthy gaps is given by Coelingh, 1999, Fig. 7, Sharman 2005. At times the Danish wind system contributes almost no electricity.

Thus day long gaps in renewable energy supply, even when drawn from a large area pose significant problems. In order to supply electricity on dark winter days when little wind is blowing, many extra wind generators must be drawn on. Thus a renewables based post-carbon grid, must include many extra wind generators inorder to provide a reliable electrical supply. Each of those generators costs money to build, and link to the grid. So the cost of the post carbon all renewables grid must include the redundant generation capacity, required to mke the grid reliable. As it turned out the cost of building redundant wind and solar generating capacity made the cost of wind and/or solar based generating systems far more expensive than nuclear systems, and thus far less likely to be built. None of the renewabvle advocates I questioned, responded to the concern related to redundency costs.

But what about energy storage? A recent post on The Oil Drum, titled A Nation Size Battery lays out some of the problems of the storage approach. The posts author Tom Murphy, an associate professor of physics at the University of California, San Diego, states:

solar and wind suffer a serious problem in that they are not always available. There are windless days, there are sunless nights, and worst of all, there are windless nights. Obviously, this calls for energy storage, allowing us to collect the energy when we can, and use it when we want.

Small-scale off-grid solar and wind installations have been doing this for a long time, typically using lead-acid batteries as the storage medium. I myself have four golf-cart batteries in my garage storing the energy from eight 130 W solar panels, and use these to power the majority of my electricity consumption at home.

Dr. Murphy is obviously not anti-renewables, but he is a rare pro-renewables realist who has analyzed the problems and is willing to go on record about what is the score:

We’re not a nation tolerant of power outages. Those big refrigerators can spoil a lot of food when the electricity drops away. A rule of thumb for remote solar installations is that you should design your storage to last for a minimum of three days with no energy input. Even then, sometimes you will “go dark” in the worst storm of the winter. This does not mean literally three days of total deprivation, but could be four consecutive days at 25% average input, so that you only haul in one day’s worth over a four day period, leaving yourself short by three.

So let’s buy ourselves security and design a battery that can last a week without any new inputs (as before, this is not literally 7 days of zero input, but could be 8 days at 12.5% average input or 10 days at 30% input). This may be able to manage the worst-case “perfect” storm of persistent clouds in the desert Southwest plus weak wind in the Plains.

Thus Dr. Murphy is trying to confront the very gap problem exposed by Dr. Trainer. Not only confront it, but describe the sort of storage system that will insure reliable electricity in an all renewables grid. He assumes that a 7 day supply of battery stored electricity would be sufficient, and that this wouldb

requires 336 billion kWh of storage. We could also use nuclear power as a baseload to offset a significant portion of the need for storage—perhaps chopping the need in two. This post deals with the narrower topic of what it would take to implement a full-scale renewable-energy battery.

Dr. Murphy then acknowledges the importance of low storage costs.

I’ll use lead-acid batteries as a baseline. Why? Because lead-acid batteries are the cheapest way to store electricity today. They’re bulky, sloshy, and very heavy, which makes them unsuitable for electric cars or laptop computers. But they’re very efficient, commonly achieving 85% or better energy efficiency in a charge cycle. The technology is well tested, having been around since 1859. And lead is a common element, being the endpoint of the alpha-decay chain of heavy elements like uranium and thorium. Their economic favorability makes lead-acid batteries hands-down the most common battery type in stand-alone renewable systems worldwide.

If the entrire grid were backed up bu a single giant lead storage battery, how much lead are we talking about?

our national battery occupies a volume of 4.4 billion cubic meters, equivalent to a cube 1.6 km (one mile) on a side. The size in itself is not a problem: we’d naturally break up the battery and distribute it around the country. This battery would demand 5 trillion kg (5 billion tons) of lead.

A USGS report from 2011 reports 80 million tons (Mt) of lead in known reserves worldwide, with 7 Mt in the U.S. A note in the report indicates that the recent demonstration of lead associated with zinc, silver, and copper deposits places the estimated (undiscovered) lead resources of the world at 1.5 billion tons. That’s still not enough to build the battery for the U.S. alone. We could chose to be optimistic and assume that more lead will be identified over time. But let’s not ignore completely the fact that at this moment in time time, no one can point to a map of the world and tell you where even 2% of the necessary lead would come from to build a lead-acid battery big enough for the U.S. And even the undiscovered but suspected lead falls short.

What about cost? At today’s price for lead, $2.50/kg, the national battery would cost $13 trillion in lead alone, and perhaps double this to fashion the raw materials into a battery (today’s deep cycle batteries retail for four times the cost of the lead within them). But I guarantee that if we really want to use more lead than we presently estimate to exist in deposits, we’re not dealing with today’s prices. Leaving this caveat aside, the naïve $25 trillion price tag is more than the annual U.S. GDP. Recall that lead-acid is currently the cheapest battery technology. Even if we sacrificed 5% of our GDP to build this battery (would be viewed as a huge sacrifice; nearly a trillion bucks a year), the project would take decades to complete.

But even then, we aren’t done: batteries are good for only so many cycles (roughly 1000, depending on depth of discharge), so the national battery would require a rotating service schedule to recycle each part once every 5 years or so. This servicing would be a massive, expensive, and never-ending undertaking.

Murphy points out the problems associated with other battery storage technologies,

I focus here on lead-acid because it’s the devil we know; it’s the cheapest storage at present, and the materials are far more abundant than lithium (13 Mt reserves worldwide, 33 Mt estimated global resources), or nickel (76 Mt global reserves, 130 Mt estimated land resources worldwide). If we ever got serious about building big storage, there will be choices other than lead-acid. But I nonetheless find it immensely instructive (and daunting) to understand what it would mean to scale a mature technology to meet our needs. It worries me that the cheapest solution we have today would break the bank just based on today’s cost of raw materials, and that we can’t even identify enough in the world to get the job done.

Murphy is still a renewables true believer, but unlike most, he acknowledges the new clothes problem.

This post does not proclaim that there is no way to build adequate storage to accommodate a fully-renewable energy infrastructure. A distributed grid helps, and an armada of gas-fired peak-load plants would offset the need for full storage. Storage can be augmented by pumped hydro, compressed air, flywheels, other battery technologies, etc.

Rather, the lesson is that we must work within serious constraints to meet future demands. We can’t just scale up the current go-to solution for renewable energy storage—we are yet again fresh out of silver bullet solutions. More generally, large scale energy storage is not a solved problem.

Such realism and candor is exceedingly rare among renewable supporters.

My conclusion in 2007 was that renewables supporters were ignoring significant problems that would make an all renewables grid hugely expensive, and that in fact they would have no choice but to fall back on carbon based technology, inorder to make the renewable approach viable. Dr. Murphy acknowledges the problem

an armada of gas-fired peak-load plants would offset the need for full storage.

But why chose carbon emitting natural gas in preference to nuclear? Natural gas will not solve the carbon problem, and there are serious environmental problems related to natural gas recovery technology. But natural gas is more acceptable in the ranks f the anti-nuclear power fanatics. The objection might be raised that nuclear power is too expensive, but any attempt to bridge the renewables intermittency gap is likely to make a non-nuclear, renewables based generation system more expensive than an alternative nuclear power based system.

The Emperor, that is a renewable based generating system has no clothes, that is it is far more expensive and far less practical than a nuclear based generating system. Most Renewable supporters, with the exception of Dr. To, Murphy, keep telling us how beautiful the Emperor's clothes are, but surely by now they must see how necked the Emperor truly is.

Google.org is still confused about paths to the energy future

Computer modelers can trip up in two ways. The model may be poorly designed in the first place. Secondly the data input may be flawed. As the old saying goes, "garbage in, garbage out." Models need to be tested, but if your model is designed to predict the future. and you foresee major changes in the future, and you want to predict the outcome of those changes, how are you going to test the model?

Google, through its philanthropic endeavor, Google.org, does not have a very good track record for predicting the future. A few years ago, Google.org produced a future energy plan. To say that the google plan was not very good is an understatement.

Google.org thought that 1100 GWs of mainly renewable generating capacity would be sufficient to run the American economy. Google believes that 360 new GWs of wind generating capacity will be needed along with 250 gigawatts by 2030 of solar installation. The rest is going to come from Geothermal, hydroelectric, and not more than 30 new nuclear plants. But where are we going to get the 1100 GWs of generating capacity? First hydro is not going to provide us with much new electricity, most of the best hydro sites are already in use, and environmental organizations have stopped hydro expansion for over a generation. We already have about 350 GWs of hydro generation capacity. Yet that hydro capacity only produces 6% of the electricity generated in the United States. Hydro generation capacity should have signaled Google.org that use that it had a problem with its model.

No one at Google seems to have been aware of the problem of solar and wind indeterminacy. Solar power systems operate at 20% of their rated capacity in the desert southwest, and much less in the cloudy Southeast. Wind generators generate at best at a little more 40% of their rated capacity on the great planes. The electricity generated by renewables will not be reliable, and will not come simply if customers throw a light switch. Customers in New York City will have to wait until the wind picks up in Amarillo before they turn on the light. Making sure that you have renewable generated electricity when consumers actually want it is going to be hugely expensive. Google did not seem to have a clue.

So I wondered why Google did not see its mistake. Then I watched a video of Google's Chairman and CEO Eric Schmidt, talking about the Google energy plan:



Son of a gun, Eric Schmidt had been drinking the cool aid with the oracle of Snowmass, Amory Lovins. The Google energy plan relied a lot on efficiency to bridge gaps in renewable energy output. This was straight out of the gospel according to Amory Lovins, but not at all realistic. I am not an Amory Lovins fan. I am only one among a goodly numer of other reviewers have pointed to flaws in Mr. Lovins' thinking. In response to numerous criticisms, Amory Lovins appears to have abandoned his defense of his efficiency theories, as well as many of his other contentions. While Lovins has abandoned his defense of many of his energy related theories, he has not abandoned the theories themselves. One of Lovins pet theory is that nuclear power is too expensive. Eric Schmidt, however, still has faith in Lovins. And drinks the Kool air from cups marked "nuclear power is too expensive," and "efficiency will save us."

If Schmidt Googled nuclear cost he would have found that numerous reputable authorities disagree with his assumptions about nuclear costs. One way of measuring comparative energy costs, it to use the so called levelized cost measure. The International Energy Agency has found that the levelized cost of nuclear power will be lower than the levelized cost of onshore wind generated electricity, even before the cost of making wind reliable is factored in. The EIA views Offshore wind and all forms of solar as more expensive.

The American Energy Information Agency theorizes that the levelized cost of wind generated electricity without the cost of measures required to make it reliable is competitively with nuclear, but cannot be expected to be substantially lower. A report coming from the UK, and published by Parsons Brinckerhof estimated that the cost of onshore wind generated electricity would be the same as the cost of nuclear. A chart from Joe Romm reflects the reality of renewable nuclear and renewable costs:Note: Romm's Chart includes the subsidized cost of renewables, as well as their unsubsidized cost. Of course even with subsidies someone pays the difference between the subsidized and the unsubsidized cost.

Levelized costs reflect the cost of electricity as it leaves the generating facility, but not as it arrives at the consumer's business or home. If the electrical generation system is unreliable, some ways must be found to overcome that unreliability, and those ways usually cost money. The cost of making energy reliable will inevitably be passed on to the consumer. In the case of renewable energy this will include a system of back up generators, or redundant renewable generators, or energy storage. None of these come free, and the consumers will have to pay. Thus the cost of reliable renewable electricity is likely to be considerably higher than the levelized cost of electricity produced by renewable installations.

It has recently been argued that low cost Chinese manufactured back up systems will diminish the cost of making renewables reliable, but the cost of Chinese labor is rapidly rising and Chinese labor is far less efficient than American or Western European labor. As a consequence jobs have already started moving backs from China to the United States, and this trend will probably continue for some time to come. Thus the use of low cost labor in China, will not decrease the cost of renewable energy backup in the long run.

Renewables require higher material inputs than nuclear power, but currently have an advantage in labor input. However labor costs can be lowered by factory manufacture, but transportation will limit the size of factory manufactured reactors. Serial manufacture also lowers reactor costs.

Small, modular, factory manufactured reactors are becoming the rage. Traditionally power reactors have been built in the on site, so they have primarily been viewed as construction projects. But there are problems with large site based manufacturing projects. Reactors have to be built to precise standards. It is not enough that all the parts get assembled, they have to be assembled to exacting specifications. And if parts or their assembly do not meet specifications, they have to be redone. In is not enough to assemble teams of skilled laborers, they have to be trained on reactor specifications and how to meet them, and then the contractor has to make sure that they have the parts and materials that meet specifications.

Large reactors require a huge amount of labor, millions of work hours, to build. In a factory, the labor tasks that are preformed by skilled workers in the field assembly of large reactors, can be turned over to machines. The use of labor saving devices makes sense if you are going to build a lot of small reactors, so small factory built modular reactors are the way to go if you want to a lot of reactors in a hurry.

The advantage of large reactors is that as reactor energy output rises, materials and labor per unit of input falls. This lowers price. There are ways to counteract this problem. As we have already seen labor costs can fall if you substitute mechanical slaves for wage earning human workers. Thus the labor costs for factory built modular reactors will decline especially as the number of manufactured unit rises. Secondly, materials can be used more if the reactor is designed to be compact. Conventional nuclear technology requires large amounts of steel in the reactor core, in pressure vessels, heat exchanges, in steam turbines, in generators and in outer containment structures. Conventional nuclear power plant design also requires a lot of concrete.

Materials inputs into nuclear power plant can be controlled by compact design, simplicity, and by choice of nuclear technology. Increasing reactor operating temperature may increase the efficiency of materials use. Paradoxically, some low temperature reactors are materials hogs, while some high temperature nuclear technologies are very parsimonious with materials. Per F. Peterson, Haihua Zhao, and Robert Petroski of University of California note,

analysis presented here suggests that the ESBWR uses 73% of the steel, and 50% of the concrete required to construct an ABWR. This suggests that new Generation III+ nuclear power construction in the U.S. will have substantially lower capital costs than was found with Generation III LWRs.

Then they add that closed cycle gas turbines

technology that will be demonstrated by the Next Generation Nuclear Plant (NGNP) has the potential to achieve comparable material inputs to LWRs at much smaller unit capacities, and when extrapolated to larger reactors, to further reductions in steel and concrete inputs.

In particular the University of California researchers like Advanced High Temperature Reactor, molten salt cooled, compact reactors.

In nuclear energy systems, the major construction inputs are steel and concrete, which comprise over 95% of the total energy input into materials. To first order, the total building volume determines total concrete volume. The quantity of concrete also plays a very important role in deciding the plant overall cost:

• Concrete related material and construction cost is important in total cost (~25% of total plant cost for 1970’s PWRs [3]);
• Concrete volume affects construction time;
• Rebar (reinforcing steel in concrete) is a large percentage of total steel input (about 0.06 MTrebar per MT reinforced concrete for 1970’s PWRs [3]);
• Rebar is about 35% of total steel for 1970’s PWRs [3];
• Concrete volume affects decommissioning cost.

Not only reactors, but also generating turbines can be made compact. For example the super critical Carbon dioxide which are compatible with high temperature reactors will be extremely compact and highly efficient. V. Dostal, M.J. Driscoll, and P. Hejzlar of MIT state,

The thermal efficiency of the advanced design is close to 50% and the reactor system with the direct supercritical CO2 cycle is ~ 24% less expensive than the steam indirect cycle and 7% less expensive than a helium direct Brayton cycle. It is expected in the future that high temperature materials will become available and a high performance design with turbine inlet temperatures of 700oC will be possible. This high performance design achieves a thermal efficiency approaching 53%, which yields additional cost savings.

The turbomachinery is highly compact and achieves efficiencies of more than 90%. For the 600 MWth/246 MWe power plant the turbine body is 1.2 m in diameter and 0.55 m long, which translates into an extremely high power density of 395 MWe/m3. The compressors are even more compact as they operate close to the critical point where the density of the fluid is higher than in the turbine. The power conversion unit that houses these components and the generator is 18 m tall and 7.6 m in diameter. Its power density (MWe/m3) is about ~ 46% higher than that of the helium GT-MHR (Gas Turbine Modular Helium Reactor).

Simplicity can also lower reactor cost. Again high operating temperature and compactness are not necessarily enemies of simplicity in NPP design.

Small compact reactors will be easier than large reactors to deploy. In order to replace fossil fuels in a little over a generation, post-carbon energy technology must be capable of large scale deployment. The nuclear manufacturing system that has been developed over the last 50 years, in addition to requiring a large skilled labor input takes several years from the time the first shovel full of soil is moved, until the electrical generators are turned on. Thus it is extremely desirable to develop energy technology that can be deployed rapidly during the next 40 years.

The small reactor is drawing increasing attention. A recent report from the Organization for Economic Cooperation and Development titled "Current Status, Technical Feasibility and Economics of Small Nuclear Reactors," noted the potential of small reactors to be a game changer. Yet the latest Google modeling effort "Examining the Impact of Clean Energy Innovation on the United States Energy System and Economy," entirely ignores the possibilities opened up by small reactors and advanced nuclear technology.

Matt Hourihan, a Clean Energy Policy Analyst at the Information Technology and Innovation Foundation (ITIF) notes significant problems with the new Google report,

Of course, the big, obvious catch is that Google makes some fairly substantial assumptions about energy costs. Some of these are quite aggressive indeed. For example, under Google’s assumptions, onshore wind costs decline by more than 50 percent by 2050 – twice as much as the IEA has predicted. The assumptions for solar PV, CCS, and the other technologies are at least as aggressive – some would say unrealistic.

Despite these flaws, Hourihan sees some good things coming out of the Google Report,

But the efficacy of these assumptions are not the point of the report, nor does it mean the report doesn’t have value: it makes clear the enormous upside, economically and environmentally, of spurring breakthrough clean technologies -- so long as we get both the technology and the policy right. It’s not a question of either/or. Any efforts to mitigate emissions that don’t seek to accelerate energy innovation will likely end in failure, and miss an economic opportunity. Under Google’s model, neither the application of a $30 per ton carbon price nor a more robust set of policies and mandates to drive cleantech adoption reduced emissions as effectively on their own as when they were coupled with breakthrough innovations to drive cost declines. It’s a similar finding we published in a report a few months ago. And relying on these policies without also driving technology would lead to slower growth relative to the innovation approach. In terms of outcomes, the best policy mix thus appears to be one that incorporates an urgent push for radical technological innovation with a broad batch of policies.

This view is clearly consistent with the views I present on Nuclear Green. The Nuclear Green views are:

* Current renewable technology is too expensive
* Technological breakthroughs are unlikely to drive the cost of renewables down
* Large Light Water Reactors are and will be too expensive, as well as too limited to satisfy many energy needs
* There are technology, product manufacturing and product packaging routs that will drive the cost of advanced nuclear power to a cost that is significantly lower than the cost of either conventional renewables or conventional renewables.
* Small, low cost, advanced nuclear power plants can solve many post-carbon energy problems that are not solvable by solar, wind, or conventional nuclear technology.
* Developmental paths that are likely to produce low cost, advanced nuclear technology have been known for over a generation, but have been ignored.

We are not at a place yet that will allow us to agree on a technology, but the time is near at hand when society must agree on its energy goals, and start to set policy. We are not there yet, but the time for confusion is clearly over. We must begin to act soon.

Harnessing Variable Renewables: Where is the Beef?

The International Energy Agency (IEA) has just published a book titled "Harnessing Variable Renewables: a Guide to the Balancing Challenge." Variable renewables refers to solar and wind power generated electricity. Balancing refers to making the grid stable when solar and wind generated electricity are plugged in.

In the best of all possible worlds such a book would be available for free down load on the Internet, so that retired guys like me, who study reports about energy technology, but who cannot afford expensive books, can look at them. Unfortunately downloading this book from the IEA will cost me €80, and 80 Euros is a little steep for me, especially as I am probably going going to find the download useless once I finish writing my review.

Why so expensive? The Press Release answers that question nicely,

Written for decision makers . . .

That means that tax payers, and rate payers will be expected to pay the bill. Hay even the IEA is not above grubbing for money when it finds deep pockets.

"Harnessing Variable Renewables" appears to be a will it work study, intended for decision makers. A will it work study is one which examines a concept and determines whether it is viable in the real world. The IEA press release explains,

Power systems must be actively managed to maintain a steady balance between supply and demand. This is already a complex task as demand varies continually. But what happens when supply becomes more variable and less certain, as with some renewable sources of electricity like wind and solar PV that fluctuate with the weather? To what extent can the resources that help power systems cope with the challenge of variability in demand also be applied to variability of supply? How large are these resources? And what share of electricity supply from variable renewables can they make possible?

There is no one-size-fits-all answer. The ways electricity is produced, transported and consumed around the world exhibit great diversity. Grids can cross borders, requiring co-ordinated international policy, or can be distinct within a single country or region. And whether found in dispatchable power plants, storage facilities, interconnections for trade or on the demand side, the flexible resource that ensures the provision of reliable power in the face of uncertainty likewise differs enormously.

Thus the question decision makers who are addressed in "Harnessing Variable Renewables" will be asking is can the variable electrical output from renewables be balanced on the grid, how can it be balanced. First the conclusion of "Harnessing Variable Renewables" that some variable renewables can be balanced is not new. Even many renewable critics acknowledge that. The real question is not will it work, but how much will it cost to make it work. Costs are the beef in the part of the title that asks, "Where is the Beef." The IEA press release is silent about costs, and so we are left to wonder if the IEA book addresses cost issues. So far none of the reviews of "HVR" I have run across mention costs, yet I would hope that decision makers would would want to know how much a balanced variable renewable grid system would cost, before the give the go ahead to implement such a system.

Reviews of "HVR" are suggestive. For example offshoreWIND.biz tells us,

Assessing flexible resources

Harnessing Variable Renewables: a Guide to the Balancing Challenge lays out a four-step method for assessing existing flexible resources, which can then be used to balance increasingly variable supply and demand. Step one of this Flexibility Assessment (FAST) method assesses the ability of the different flexible resources to change their production or consumption; step two examines the aspects of the power system that will constrain them from doing so; step three calculates the maximum requirement for flexibility of a given system resulting from fluctuating demand and output from wind plants and the like; and step four identifies how much more variability can be balanced with existing flexible resources.

The book features eight case studies in which the FAST Method is applied to eight geographic areas with very different characteristics. The resulting analysis shows that each region has the technical resources to balance large shares of variable renewable energy.

Potentials range from 19% in the least flexible area assessed (Japan) to 63% in the most flexible area (Denmark). The IEA also assessed the resources of the British Isles (Great Britain and Ireland together), 31%; the Iberian Peninsula (Spain and Portugal together), 27%; Mexico, 29%; the Nordic Power Market (Denmark, Finland, Norway and Sweden), 48%; the Western Interconnection of the United States, 45%; and the area operated by the New Brunswick System Operator in Eastern Canada, 37%.

This range of results is due to the different flexible resources found in these areas. Norway, for example, has extensive hydropower, which is a very flexible resource; while Japan’s power plants, many of which run on nuclear and coal, are not as flexible (e.g. it takes longer for these sources to respond to fluctuations in demand).

Thus the assumption by the the IEA researchers is that grid managers will draw on existing grid resources to back up renewable energy. The study finds in effect that their are limitations to renewable grid penetration posed by reliance on existing grid resources. Indeed in most countries renewable grid penetration of less than 50% will be possible are using existing grid resources for balancing.

This means that for most countries a high renewables grid penetration system discussed in "HVR" is only at best a bridge to the 4/5th fossil fuel reduction that climate scientists envision us requiring by 2050. But can a renewables only system take us all the way to an energy future than produces only 20% of the CO2 produced today by fossil fuels?

There are clearly grounds for doubt, and clearly grounds for wondering it is going to be possible to produce 80% of all energy resources through reliance on renewables, how much will it cost to do so.

As I have pointed out decision makers need to know how much a balanced high renewables penetration system will cost. If "HVR" addressed the cost issue and offered good news, the pro-renewable reviewers, and indeed the press release would have mentioned that fact. If it did not address cost issues, then decision makers lack important information that are required to make appropriate decisions or the future sources of post-carbon energy.

Since I have no information on costs related to the "HVR" case studies, I will have to go with my own case studies, and since the United States Western Interconnect is one of the cases studied, I will note a previous Nuclear Green post, "The cost of carbon mitigation with renewables." In that post I discussed the Eastern Wind Integration and Transmission Study and , How do Wind and Solar Power Affect Grid Operations: The Western Wind and Solar Integration Study.These studies looked at 30% to 35% renewablea penetration of the two largest North American interconnects. Not quite as high as the 48% maximum penetration which "HVR" envisioned for the Western Interconnection. I noted that there were both significant connections about the actual CO2 mitigation that

As with all National Renewables Energy Laboratory reports, the WWSIS made no attempt to compare renewables costs and performance with nuclear power. But a relatively simple thought experiment can yield some very telling results. First we can assume that nuclear power will displace coal rather than CCGT. The Energy Information Agency estimates that the levelized cost of Advanced Nuclear will be 119.0, or about 12 cents per kWh. If nuclear displaces coal at that cost, the cost of displacing one ton of CO2 would be $119. Now let us take the 11% renewables case. The 2016 levelized cost of wind is 149.3, while the levelized cost of solar thermal is 256.6. Thus the average levelized cost of the 11% renewables is 159.08, and the cost of displacing a ton of CO2 with renewables is $159.0 + transmission costs and other hidden cost of wind generation systems, and the added CO2 emissions of fossil fuel wind backups kept spinning. plus the added CO2 efficiencies of fossil fuel generators used in load leveling and load following roles. Since wind is displacing relatively carbon efficient CCGTs rather than carbon inefficient coal fired generating plants. each MW of CCGT power displaced would produce 800 pounds of CO2, rather than a ton of CO2 produced by the equivalent electrical output of a coal fired power plant. Thus carbon mitigation with the 11% wind April scenario will cost about $400 + hidden costs or over three times as much as nuclear power would costs.

In the April 35% penetration case, wind becomes the predominate source of electricity on most days, and it displaces 2/3rds of coal generation capacity and all the CCGTs. Yet for the July 35% penetration case, wind failed to displace most CCGTs and no coal. Thus the WWSIS study data reported provided in sufficient information for understanding the the potential carbon mitigation costs . However it should be noted that the DoE study, Eastern Wind Integration and Transmission Study(EWITS) found that the cost of total system electrical output increased dramatically as wind penetration rose to 30%.

I concluded that,

Clearly then increasing wind penetration in the West will increase the level of carbon mitigation as well as its costs. It is also clear that wind displaces CCGTs before it displaces coal, and this increases the cost of carbon mitigation by wind significantly. Carbon mitigation with conventional nuclear would thus appear well over 3 times more cost effective compared to carbon mitigation with wind. The true cost effectiveness advantage of nuclear cannot be gaged until we know more about the hidden costs of wind, but the hidden costs appear to extract greater cost penalties at higher levels of wind grid penetration.

These conclusions suggest that Wind and Solar energy at high penetrations may not be cost effective tools for carbon mitigation. Taken all together, what we know about the contents of "HVR" is consistent with variable renewables being a questionable and expensive bridge to a low carbon future.