Consumer Energy Report is now Energy Trends Insider -- Read More »

By Robert Rapier on Apr 30, 2013 with 33 responses

The Key to Running the World on Solar and Wind Power


Perhaps the biggest shortcoming of solar and wind power is their intermittency. In locations like Hawaii, where I live, wind and solar power are already competitive on price. My fossil-fuel supplied electricity typically costs above 40 cents a kilowatt-hour, and wind and solar power can compete with that. But since they can’t supply power that is available on demand (firm power) they must be backed up by power sources that can provide power when the sun isn’t shining and the wind isn’t blowing.

This scenario could change dramatically if cost-effective energy storage solutions were developed. I consider this to be the most important unresolved problem in the energy business. A company that develops a way to efficiently and economically store intermittent energy for on-demand use will be a game-changer.

The ideal power storage solution would be able to store energy densely, at a reasonable capital cost, and would be able to return that power at high efficiency. For instance, if we put 1 unit of power into the storage system and we actually got 1 unit back out when we needed it, the system would be 100% efficient. Real-life efficiencies will be less than 100%, but the higher the efficiency, the more desirable the storage option.

A new report on energy storage from Navigant Research predicts that the market for energy storage for the electric grid could surpass $30 billion annually by 2022. Some of the potential options include batteries, pumped hydropower, compressed air energy storage (CAES), flywheels, hydrogen, and fuel cells. And of course nature also has a built-in storage mechanism for solar power (albeit an inefficient one) called biomass.

The following figure highlights the biggest problem with most energy storage options — the energy density is simply too low. Energy density measures the amount of energy stored per unit of volume or weight. What this means is that for a given volume or a given weight, the storage options can store only a tiny fraction of energy relative to liquid fuels.

Energy Density

The most energy dense options possible would be those at the top and to the right of the graphic. Were Uranium-235 included, it would have appeared at the top right corner, but far beyond the scale of this graphic. The least energy-dense options would be those at the bottom left of the graphic, which is where we find batteries, flywheels, and compressed air. At this scale, the energy density of these storage options appears to be near zero. Relatively speaking, gasoline contains more than 50 times the energy of the same volume of a nickel-metal hydride battery.

Pumped hydropower storage (PHS) is a storage option that is already commercially used in some conventional power plants. The concept is that off-peak power is used to pump water up to a reservoir at a higher elevation, and then returned through turbines to produce electricity. A March 2012 report by the Electric Power Research Institute (EPRI) indicated that PHS accounts for 99 percent of utility-scale storage capacity worldwide. PHS has a reported round-trip efficiency of about 75 percent, considerably higher than that of many other storage options.

There are around 50 PHS systems of at least 1 gigawatt (GW) installed around the world, with another 15 or so facilities of this size under construction. Operating facilities exist in the US, China, Japan, South Africa, Russia, Australia, South Korea and in a number of European countries. The largest facility in the world is a 3 GW system in Bath County, Virginia.

The primary advantage of PHS is that very large amounts of power can be stored for long periods of time, but accessed quickly. The major disadvantages are that initial capital costs are high and the technology is limited by geography to locations that can host a large reservoir at a significantly higher elevation than the power station.

Compressed air energy storage (CAES) is the second largest category of utility-scale energy storage. In a CAES system, off-peak power is used to compress air into a storage reservoir, which is later released through a turbine to produce electricity as needed. This reservoir is typically an underground cavern, but some work is being done to develop these systems under water, in enclosed bags that expand against the outside water pressure.

The first utility-scale CAES facility was built in Germany in 1978, utilizing a salt dome as the reservoir. The first system in the US was built in 1991 in Alabama. A salt cavern is also used in this system, which can compress air up to 1100 pounds per square inch (psi). Other projects are under development, with the US Department of Energy providing funding in some cases.

As with PHS, CAES is limited by geography. Further, the cycle efficiency of the systems currently operating is reportedly 40 percent or less — much lower than with PHS.

Hydrogen is one of the more energy-dense storage options by weight. One kilogram (kg) of hydrogen compressed to a pressure of 150 bar (2,175 psi) actually stores a lot more energy than one kg of gasoline (the horizontal axis is energy density by weight). As shown in the graphic, compressed hydrogen contains more than three times the energy of gasoline per kg (142 megajoules for hydrogen versus 46 megajoules for gasoline).

However, hydrogen falls short when it comes to volumetric storage (the vertical axis). One liter of gasoline contains over 20 times the energy of one liter of 150 bar hydrogen. Thus, one of the limitations of hydrogen as a fuel is that the range of a vehicle running on hydrogen will fall far short of that vehicle utilizing a similar-sized gasoline tank.

Nevertheless, the German utility E.ON (OTC: EONGY, Frankfurt: EOAA) is investing in a hydrogen-based storage system. In 2012 E.ON contracted with Canada’s Hydrogenics (NASDAQ:HYGS) to install a power-to-gas system in Falkenhagen, Germany. The idea in this case is that off-peak power is used to make hydrogen from water by electrolysis, and then the hydrogen is injected into a natural gas pipeline. The hydrogen-natural gas mixture can then be used as needed for power production, or for heating.

Of course energy is lost when water is broken down into hydrogen and oxygen. The efficiency of electrolysis of water into hydrogen can be as high as 85 percent. Hydrogenics reports that the efficiency of its hydrogen fuel cells “is greater than 55 percent” in converting hydrogen into electricity. So we could expect the cycle of converting off-peak power into hydrogen and then back to electricity during peak demand would be (0.85) * (0.55) = 47 percent efficient. In other words, a little more than half of the power sent to storage is wasted.

This also implies that the value of peak power would need to be more than twice the value of off-peak power to make such storage profitable. For example, if off-peak power is worth a nickel, and peak power is worth a dime, then a nickel’s worth of power sent to storage is only worth 4.7 cents (47% of a dime) at peak demand. On the other hand, if peak power is worth 15 cents in this scenario, a nickel’s worth of off-peak power can be turned into 7 cents of peak power (47% of 15 cents).

Batteries comprise an enormous global market, and are often used in personal solar systems to provide power at night. But batteries are seldom used to back up power plants because they have low energy density, are expensive, and have a limited lifespan. However, a great deal of research is being devoted to the development of advanced batteries, which are projected to reach gigawatt levels of utility-scale storage over the next 10 years.

Governments are investing heavily in the development of utility-scale storage, and a number of utility-scale storage possibilities are still in development. This is an area that promises to grow rapidly in the coming years given the number of countries implementing aggressive renewable electricity standards.

See also: The Most Important Problem in Renewable Energy — R-Squared Energy TV Ep. 22

Link to Original Article: The Key to Running the World on Solar and Wind Power

By Robert Rapier. You can find me on TwitterLinkedIn, or Facebook.

  1. By Will Stewart on April 30, 2013 at 4:19 pm

    If you are talking about 100% renewables with the bulk being wind and solar, then indeed storage is paramount, though the need can be greatly through the use of Demand Management (whether load deferral, price-induced conservation, etc).

    Don’t forget other renewables such as baseload geothermal, non-variable tidal, dispatchable biomass, etc.

    Also note ammonia from excess renewable generation can be a form of storage;

    If we are talking hypothetically about a significant (>75%) of just wind and solar, then natural gas ‘gap-filling’ can be realized with peaker plants. Add in more geothermal, tidal, biomass, etc, and the ‘valleys’ become shorter and shallower.

    • By BilB on May 7, 2013 at 11:37 am

      The most interesting recent addition to the basket of storage technology (proposals) was for offshore wind turbines. This involved huge concrete submerged spheres, while also served as anchors for the turbines, are able to be pumped out with surplus energy then refilled with water through turbines or piston devices to recover the energy. If pumped hydro storage is considered to be top down then this system is exactly the same only bottom up.
      The only negative is that as the spheres are pumped out they will become more bouyant, and so loose some of their anchor power.

  2. By GidonG on May 1, 2013 at 12:48 am

    Excellent overview of the options for energy storage.

    I understand that thermal solar plants (which use molten salts to produce steam for electricity generation) can use the molten salts for energy storage to produce electricity after sunset.

    On the stored hydro front, Belgium (which has no valleys that could be flooded for pumped storage without annoying the local population) decided to build an artificial island in the North Sea to store excess wind energy.

  3. By Benjamin Cole on May 1, 2013 at 3:04 am

    It may be that someday used auto batteries (the PHEV or BEV kind, that is), while not perfect, will be cheap and available and useful in energy storage for those people so inclined. I can imagine a crafty fellow setting up solar panels on his roof–possibly also bought used—and maybe a wind turbine, and a PHEV battery, and doing okay by it all.

    A person in Hawaii could also probably collect rainwater.

    But, with natural gas prices looking low for a long while, not sure this would make sense for most mainland applications.

  4. By Eric L on May 1, 2013 at 3:33 am

    Volumetric density and gravimetric density are important when you’re powering a car, but neither is particularly important for grid storage. What matters is MJ/$, and efficiency.

    • By Cl1ffClav3n on June 17, 2013 at 7:31 am

      In addition to dollar cost and efficiency, what matters most is power density (W/m2). Land is expensive and using it to generate or store power competes with using it for commercial, residential, industrial, or environmental and aesthetic purposes. Power density does depend upon the volumetric energy density of the fuels, batteries, capacitors, flywheels, elevated water, chemicals, or whatever is used to store energy .

  5. By Elias Hinckley on May 1, 2013 at 8:47 am

    Some interesting stuff happening with molten salt as thermal storage (not just is CSP context) as well. Also would point to advances in system controls that can use demand response to mimic storage.

  6. By Eric on May 1, 2013 at 10:37 am

    Robert, one of the nice properties of pumped hydro is that it could actually be used as a buffer for grid stabilization. Connecting wind directly to the grid causes substantial challenges with frequency management and stability. Using wind only to pump water into the reservoir would allow the hydro generators to be the only grid-connected equipment – making utilities MUCH happier about renewable integration. CAPEX issues aside, wind energy is cheap enough for this to work financially. In places like the Pacific Northwest, this would actually integrate well with existing hydro resources since it’s already being done to a limited extent.

  7. By Tom G. on May 1, 2013 at 11:03 am

    Well written piece Robert.

    As you know my son lives on Kauai and states his electric bill is approximately $100.00/mo. That buys the amount of electricity needed for lighting, TVs, modems, computers, etc. Hot water and cooking are provided by propane. At that level of energy consumption for a family of 3 and ~1500 sq.ft. home he does not seem to be a valuable target for a wind or solar salesman.

    However, in your piece you wrote: “Relatively speaking, gasoline contains more than 50 times the energy of the same volume of a nickel-metal hydride battery.”.

    However, since a battery can be recharged at least 100′s of times aren’t we really talking oranges and apples when we compare liquid fuel use to energy storage [and use] in batteries? Once the gasoline or propane is gone its gone, and must be replaced. Once the energy in a battery is used it can be recharged. Therefor does energy density really come into play or do we need a multiplier applied when we start talking about renewable energy systems?

  8. By ben on May 1, 2013 at 4:12 pm

    After reading Lou Gagliardi’s most recent and, typically, no-nonsense piece about meeting a 100Mbpd production challenge– a goal that is quite likely to prove every bit as necessary as it is elusive–I welcome your insights on solar, wind and other options.

    Suffice it to say our challenges remain daunting and, by most objective accounts, the prospects of achieving steady progress in meeting our energy requirements for even sub-par economic growth remains very much in doubt.

    Nothwithstanding the rosy scenario painted in the current issue of Atlantic Monthly by Charles C. Mann, the era of abundant/affordable energy supplies is hardly a settled matter. Indeed, Stuart Staniford has recenlty done a fine job in pointing out with his telling charts, the prospects for slower GDP growth as a consequence of rising energy demand and correspondingly higher energy costs/prices points to an era of constraints. That such constraints will prove troublesome for various national economies remains the province of public policies and the dynamism of entrepreneurial pursuits. To that end, the roll that incentives can play should not be over nor under-estimated. Prices remain a powerful arbiter while market mechanism are allowed to inform judgments about resource allocation. Fostering the development of risk-mitigating, profit-promoting measures in capital markets is no less important. For those who look longingly for viable alternatives to traditional market forces as a principal method of achieving renewed or, better yet, “sustainable” economic growth, the discipline must be one of feasibility not that of wishful thinking.

    Debate among those adhering to a school of thought that places ecological principles
    at the very heart of an informed view of growth vis-a-vis those who resist the subordination of economics to such notions remains the rub. Neo-classical economics has, in the view of academics of the so-called Left, suffers from a glaring deficiency: a willingness to acknowledge that their allegedly positivist (empirical) methodology is little more than academic hubris. Likewise, the “traditionalist” among trained economists resist the normative (subjective) treatment of economic data that invites (intentionally or not) a degree of ideology (politics) into economic analysis and resulting policy pronouncements. The sad truth is that neither side offers the public much confidence about practical solutions that aim to meet our most pressing economic challenges. The prospects of acheiving any near-term consensus proving stubbornly elusive even as politics remains, as ever, the mere art of the possible.

    Perhaps at some point in the future, we can advance the earnest work of achieving a non-ideological consensus on what makes good sense for America and that of our neighbors. One can only hope this may be undertaken with a serious-minded determination to promote a commonwealth of free nations with each enjoying their respective and shared blessings of liberty.



  9. By Tom G. on May 1, 2013 at 4:40 pm

    Dear Ben:

    At 73 I must be getting really old since I had difficulty trying to understand the point[s] you were trying to make in your posting. I ran a couple of your paragraphs through the Gunning Fox Index and it revealed 18.58 – 19.60.

    You are writing way above my education level my good man.

  10. By ben on May 1, 2013 at 6:04 pm

    Dear Tom:

    Might you offer a Gunning Fox Index on say the Federalist Papers given that they served as the most widely read and, dare I say, compelling reasoning in defence of the Constitution’s adoption?

    The objective here is, and shall ever remain, a simple observation of the facts and circumstances accompanying the tough choices at hand. I strive never to underestimate the intelligence of the readers nor that of the average citizen seeking to know and act in way consistent with their own interests and that of their neighbors. To the extent my ramblings ever escape such a practical standard, I sincerely offer a humble apology. I do remain grateful for the opportunity to share two-cents from Gold Coast of West Africa.

    Thanks for the benefit of your candor and constructive counsel, sir. Might I also add that at 73, you are about to hit your prime; a point that I’ll be making to my dear father in the near future:)


  11. By Tom G. on May 2, 2013 at 2:10 am

    For some R Squared readers the subject of the Federalist Papers will certainly be considered off topic but hopefully a few will still find this posting interesting. According
    to Wikipedia; “The Federalist Papers are a series of 85 articles and essays written by Alexander Hamilton, James Madison, and John Jay promoting the ratification of the United States Constitution.”. These writings are frequently quoted and used by our Supreme Court justices. They are also frequently assigned as required reading for
    American high school students.

    Writing and speaking clearly are important learned skills. As an engineer by profession, I was taught by an engineering group leader early in my career that if you can’t write and speak well, your career will most likely suffer even if you are an outstanding engineer. Early in my college years I was introduced to many tools that helped me succeed. One such tool is called the Gunning Fog Index which you can find described in the following Wikipedia article.

    So lets get back to the Federalist Papers and Mr. Alexander Hamilton. How clearly did he write or convey his message? How successful was he at selling his message? Here is a short sample of his writing and the associated Gunning Fox Index.

    “The three last numbers of this paper have been dedicated to an enumeration of the dangers to which we should be exposed, in a state of disunion, from the arms and arts of foreign nations. I shall now proceed to delineate dangers of a different and, perhaps, still more alarming kind–those which will in all probability flow from
    dissensions between the States themselves, and from domestic factions and convulsions.”. [Gunning Fog Index of 19.02, Grade level 19 or a Masters Level].

    Certainly not an easy read for a High School student. How about the writings of James Madison.

    “It is not a little remarkable that in every case reported by ancient history, in which government has been established with deliberation and consent, the task of framing it has not been committed to an assembly of men, but has been performed by some individual citizen of preeminent wisdom and approved integrity.”. [Gunning Fog Index of 30.03, Grade Level 30, Doctorate Level]

    To me this is not an easy read either. And our last individual John Jay. What was his writing level?

    “Should the people of America divide themselves into three or four nations, would not the same thing happen? Would not similar jealousies arise, and be in like manner cherished? Instead of their being “joined in affection” and free from all apprehension of different “interests,” envy and jealousy would soon extinguish confidence and affection, and the partial interests of each confederacy, instead of the general interests of all America, would be the only objects of their policy and pursuits”. [Gunning Fog Index of 25.34, Doctorate].

    Certainly not an easy read but of the 3 authors, I find John Jay to be the most readable even if the Gunning Fog Index number is quite high.

    So what does this have to do with solar and wind power? Well, if you believe in and want to promote these energy sources; then having the ability to write clearly is
    important. A tool like the Gunning Fog Index should help develop such skills. I periodically check my writing and strive for something between 10 and 14. That means that about 40% of the general public should be able to understand what I write based on demographics data. If I wrote at the Doctorate Level my potential
    audience would drop to about 2%. By the way; the Gunning Fog Index for this paragraph is about 10].

    Thank you for taking the time to read this posting.

  12. By Andrew Holland on May 2, 2013 at 10:48 am

    Here’s a fun one for energy storage: drive a train up a hill. Then, let it slowly roll back down the hill, collecting the energy as it goes down. Here’s the company in Southern Cal that is doing it:

    I wonder where that would fit on the chart?

    • By Robert Rapier on May 2, 2013 at 7:36 pm


      There is a concept that has gotten some attention. I read recently about driving a very heavy piston up and then letting it come back down by gravity with the energy is needed. The claim was that the efficiency is better than pumped hydro storage.

      • By mechanieker on May 6, 2013 at 4:21 am

        Of course, the energy density of such schemes is abysmal. For the fun of it, assume the piston is 2 meters tall and then calculate how much mass you need in order to store 14 kWh(e), which is about the daily electricity usage of a typical 5000 kWh(e) a year household. I calculate you would need a piston that weigh 2500 tons, or the equivalent of 1000 SUV’s.

        It seems clear to me that the electricity storage issue is a show-stopper for wind and solar energy. Therefore, I conclude that nuclear power is the only way to cost effectively displace fossil fuels. Nuclear power can also be used to synthesize liquid fuels at a cost that is lower than today’s barrel of crude oil.

        By the way, Mr. Rapier, in your article you say that uranium would be positioned in the top right corner of the chart. I’m sure you know that in fact the chart is not currently scaled to allow the positioning of uranium. In order to include uranium (or thorium) in this chart, the chart axes would need to be extend by millions of times in both directions. The energy density of uranium is of the order of millions and billions of MJ per kg or liter respectively. I’m sure you know this, so I wonder why you felt this point didn’t deserve some more discussion in the article?

        • By Robert Rapier on May 6, 2013 at 4:34 am

          “I’m sure you know this, so I wonder why you felt this point didn’t deserve some more discussion in the article?”

          That’s a fair point, but I never thought of anyone literally taking my meaning as the energy density of uranium is 150 MJ/kg. My comment was meant to convey simply that uranium is a far more energy dense material than the other options. But yes, I should probably edit the article so people don’t think I mean that it would literally fit on the scale of this chart.

          • By mechanieker on May 6, 2013 at 6:19 am

            Thanks for this explanation. I tend to be perhaps overly critical about such things, but that is because there is already so much confusion about nuclear energy. For instance, most people think that there is a problem with future uranium supply, or that getting uranium out of the ground or the oceans has a poor EROEI. This stops many people from doing a full analysis of our global energy and GHG emissions problems. It stops them from considering what role uranium can (and should IMHO) play. That role is large. Uranium can supply all our energy needs cleanly, inexpensively, and for tens of thousands of years at least.

            Certainly, pumped hydro storage is an excellent way to store intermittently produced electrical energy. But unfortunately, there is not enough spare capacity or capacity expansion available to cover global storage needs in a global 100% intermittent renewable scenario. We don’t even get close. So inevitably, we are going to need alternative storage technology. But my conclusion is that those alternatives are – and will remain – too expensive to compete with fossils. Therefore, they will not be implemented.

            My conclusion is that we will need at least 50% of our total energy requirement to be met by nuclear power and nuclear liquid fuel synthesis. More would be better. This is the only credible way to get off fossil fuels in a timely fashion and without the high costs that will fatally undermine political support for solar and wind far before we reach anywhere near the 100% decarbonisation goal. The imminent failure of the German ‘Energywende’ will make this clear for everybody within a few years. That ‘Energywende’ is about to predictably collapse in (political) disarray.

  13. By Tom G. on May 2, 2013 at 1:50 pm

    Interesting video Andrew. There is an area in California about 60 miles from where I live in Arizona that would be perfect for this application. Thousands and thousands of acres of open desert for solar PV and a gentle slope running for miles that would eliminate most of the grading needed for the railroad tracks. Even has existing transmission lines nearby which could be doubled up to carry the new generation capacity.

    Ah yes I can see it now – 5 Gigawatts of clean solar power available 24/7 350 days a year. Just about like building 5 new 1000 MW nuclear power plants but without the need for millions of gallons of water. The other 15 days of the year its either cloudy or raining so power output would be limited on those days, LOL

    The only problem I see is the rotating or turning mass/weights. Seems like an unnecessary complexity when sufficient land space is available.

    Have a great day.

  14. By ben on May 2, 2013 at 2:34 pm


    Thanks for the GFI on the writings of three of my favorites. One may argue the Federalist Papers are peripheral to ETI’s principal focus, however, I am not one to discourage their timeless contribution to good reason and wise reflection.
    You have, in my humble opinion, performed a useful service here; familiarity with the contributions of the Framers is never without redeeming value. To confirm that each man wrote at an elevated level is unsurprising. What is, perhaps, a bit disconcerting is the recognition that a good portion of the serious-minded folks of Colonial America were sufficiently equipped, despite a general lack of formal education, to read and reflect on the writings of these learned men. That tends to give one pause in wondering just how much “progress” we’ve actually made these past two and a quarter centuries. Indeed, it induces a degree of sober judgment about our current state of affairs and the prospects of making genuine headway in meeting the daunting challenges at hand.
    Mr. Rapier and his ETI colleagues certainly endeavor to consistently do their part in elevating the discussion on energy-related issues. For that alone, I remain in their debt. I am quick to add here that I feel no less gratitude for your own contributions, and that of other readers, in helping to address many of the important issues of the
    day in this same space. One only hopes that some of this stirring of the pot may eventually contribute to a better porridge. Put another way, I guess the proof of that may be found in the pudding:)

    • By Tom G. on May 2, 2013 at 3:13 pm

      Very well said young man and my best wishes to your father when you visit.

      Have a great day.

  15. By Nick G on May 2, 2013 at 3:37 pm


    This topic is way too big to cover in a single, general article. Nevertheless, there is one level of detail that needs to be included, namely that there are several very distinct and different markets for storage. It confuses things enormously to mix them together.

    There’s the need for extended seasonal storage, when both wind and sun are low for several weeks. That requires very low capital costs to proved a large capacity, but efficiency isn’t very important, as it would only provide 5% or less of the annual kWhs supplied. Hydrogen is perfect for this, either mixed with methane, or stored underground. These are well proven technologies. On the other hand, we may need much less of it than one might think, as other cheaper strategies may solve most of the problem, including Demand Response (aka Demand Side Management), weather forecasting, long distance averaging, V2G, etc, etc.

    There’s the need for daily storage, to deal with daily variation. That needs high efficiency, as the percent of power than is cycled through it will be higher. On the other hand, it’s maximum capacity will be much, much lower, so it can accept higher capital costs. Batteries will work well for this, particularly those already sold as part of EVs. Pumped storage is an obvious solution for this, and hydrogen (despite lower efficiency) might work as well. This area will be very dynamic in years to come.
    Finally, there’s personal transportation, which needs high energy and power density, and can accept high capital costs. Here batteries will do well, and hydrogen is a non-starter.

    • By Tom G. on May 2, 2013 at 5:41 pm

      Very well written Nick G and you are totally correct. Generally speaking there are different types of generation [and storage needs] for different types of grid needs. Intermittent, base-load, peaking and spinning reserves are but a few types.

      But the thing I find most shocking or maybe I should say distressing; is our unwillingness or fixation on the perceived problem of adding more renewable energy systems into our generation mix. For example, when I looked at the California ISO grid today this is what I found at about 1:00 p.m.

      Today’s projected peak ~33,253 MW
      Today’s expected min. ~ 21,000 MW
      Today’s Available ~ 41,000 MW
      Available from Renewables ~ 4,103 MW

      So today only about 12% of the power being use in most of California is coming from the following renewable resources.

      Wind ~ 1100 MW
      Solar ~1500 MW
      Geothermal ~820 MW
      Bio Mass ~280 MW
      Bio Gas ~180 MW
      Small Hydro ~370 MW

      That must mean that about 88% of the remaining energy is coming from other non-renewable energy sources like coal, natural gas and a small amount of nuclear.

      Now here is where I start living in a fantasy land. I believe it would be quite easy to add at least 10,000 MW of new renewable energy systems before we need to even begin to think about grid stability or energy storage systems. Especially if those resources were diversified and distributed over a large area. That 10,000 MW wouldn’t even fill the gap between peak demand and minimum demand which is 12,253 MW but it would go a long way to eliminating the need for coal generation. And as far as adding more backup generation to the mix; why do that when we already have 7,747 MW of excess generating capacity just sitting idle.

      By now you should realize that there are powers at work here that do not care if we have a better environment to live in or not.

      Thank you for posting your thoughts Nick G.

  16. By Alan Drake on May 4, 2013 at 10:53 am

    Pumped storage is the best solution, and a number of pumped storage schemes have been proposed around the Hawaiian Islands.

  17. By Ken Fabian on May 4, 2013 at 5:59 pm

    When it comes to utility scale (stationary) storage – it’s not currently needed by energy producers and distributors, especially those who are resisting a shift away from fossil fuels and because of that unfortunate choice, it’s a very low R&D and investment priority. Actually it’s in their (not very forward looking) interests that there isn’t anything currently up to their (not very enthusiastic) requirements for adopting large scale storage.

    But large scale storage isn’t rocket science and is unlikely to require any great breakthroughs to achieve – just a conviction within the energy sector that it’s going to be a major part of their future business model and therefore something worth significant investment.

    As an example of long established technology applied innovatively to this problem, there is Isentropic Ltd’s Utility Scale Pumped Heat Electricity Storage system (not mentioned here) that is claiming storage costs lower than pumped Hydro – without the geographic and climatic restraints and a fraction of the space requirements.

  18. By Russ Finley on May 4, 2013 at 11:39 pm

    The graphic below gives a feel for the scales involved. If you could zoom in on the line at the bottom you would see a jagged curve representing pumped storage and it is all a net energy loss. Note in this chart that the values in the pumped storage column for net energy generation are all negative (it is all consumed by the power plant’s own power needs and never reaches the grid).

    Low-cost off-peak electric power is used to run the pumps. During periods of high electrical demand, the stored water is released through turbines to produce electric power. Although the losses of the pumping process makes the plant a net consumer of energy overall, the system increases revenue by selling more electricity during periods of peak demand, when electricity prices are highest.

    The market is always seeking higher profit (does not tend to leave money sitting on the table). Pumped storage is an old idea, used when feasible. We see so little of it simply because it is not usually profitable to use it (cost of extra infrastructure would never pay itself off).

    RTOs use locational marginal pricing (LMP). Prices are determined at thousands of locations. Prices are also determined hourly and on a 5-minute basis.

    Technical and economic factors lead power plant operators to run generators even when power supply outstrips demand.

    It makes no difference which type of power plant pumps the water. It could be a nuclear power plant at night during low demand. The stored energy could still back-up wind and solar when they quit.

    Most nuclear power plants are located near a large body of water for cooling, so you wouldn’t have to build a lower reservoir, just the upper one.

    • By Warren Stephens on May 8, 2013 at 12:21 pm

      > jagged curve representing pumped storage and it is all a net energy loss
      > It makes no difference which type of power plant pumps the water

      Suppose I put a very large funnel scoop in the ocean, pointed directly into a strong current, could it drive water through a pipe to the top of a hydro facility at a useful scale? It’s a “free” pump!

  19. By Tom G. on May 5, 2013 at 11:56 am

    Good posting Russ:

    Many people forget that when we say something is 70% efficient, what we are really saying is that the other 30% must be lost someplace in the process. Its like a coal or nuclear power plant; most are about 30-35% efficient in converting boiler or reactor heat into kilowatts of electricity which means the other 70% is waste heat.

    Everyone should realize that we are wasting about 70% of the fuel or heat energy we use to create electrical energy. The more energy we create the greater the problem waste heat becomes. This waste heat is already affecting weather patterns up to 1000 miles from some of our cities. Here is a Google search link you might find interesting .'+waste+heat+affects+air&rlz=1C1AVSX_enUS414US430&oq=Cities'+waste+heat+affects+air&sourceid=chrome&ie=UTF-8

    By the way; the next multi-billionaire will probably be the person or persons that develop methods or techniques to either capture and use the waste heat or reduce the inefficiencies. That my friend is something worth studying and working on in your garage.

  20. By Luke on May 6, 2013 at 11:43 pm

    Very interesting.

  21. By Jeff S on May 8, 2013 at 12:40 pm

    Wouldn’t this be something best accomplished at a local level? As opposed to large capital budgeting approvals needed for the R&D, and threatened by bottom line results, I believe the focus should be placed on the most granular level possible; i.e. what can we all deploy at our homes in efforts to store energy? The next billionaire will be the one who addresses the problem at the smallest scale possible, and provides a CHEAP implementaion. I’m still waiting for my chance to purchase a bloom box to run my house on.

    • By Tom G. on May 8, 2013 at 5:35 pm

      Excellent comments Jeff S expecially about the bloom box. It would be a good choice for many people if they had access to cheap Natural Gas which I don’t. All I have here in Arizona is sunshine about 350 days a year, LOL

  22. By Moiety on May 10, 2013 at 8:05 am

    It is a tough area though to make an impact. When I was at ECN, there were a good few projcts on storage but all in terms of cost were essentially pegging themselves to batteries or to some other storage mechanism. As you show here these are not particularly good so a 20% change on these is not going to change the world.
    At least in biomass while corn ethanol is not great compared to petriol, it is not far off in certain niche applications. Storage seems to need a step change.

  23. By Cl1ffClav3n on May 15, 2013 at 5:23 pm

    Fossil fuel power plants already have high-efficiency power storage–in their coal stockyards and tank farms–i.e., in their fuel. The best way to store energy is pre-generation and especially pre-combustion. A large part of a cost-effective grid-scale solution is likely to be fielding a fleet of fuel-fed generators that are highly dispatchable, have quick ramp times, and maintain high efficiency across a large operating range. Better to burn only the fuel you need when and where you need it than to burn twice as much during the off hours knowing you will only get half the energy back later–much better for fuel consumption, the environment, GHG emissions, and consumer power bills. Super-clean oxy-combustion units modularized to 100 MW or even 25 MW units that can ramp up to full output in less than one minute might be a good course of action to consider. This is not to say that storing electricity is not part of the solution, but perhaps it is a minor part.

Register or log in now to save your comments and get priority moderation!