Published on September 13th, 2013 | by Silvio Marcacci


Study: Battery Energy Storage Benefits Solar, Not Wind

September 13th, 2013 by  

Everyone knows energy storage is the key to unlocking renewable energy’s full potential, right? Well, not always, says new research from Stanford University.

Utility-scale batteries make sense for storing electricity from large solar power systems, but not wind farms, according to analysis published in the journal Energy & Environmental Science.

If true, this research could undercut one of the most promising opportunities to solve intermittency concerns from renewable power sources and better integrate wind and solar onto the grid.

Low battery

Low battery image via Shutterstock

Can Energy Storage Solve Intermittency Issues?

Energy intermittency from renewables (meaning the relative unpredictability of the wind blowing or the sun shining) is one of the biggest challenges facing our transition to a clean energy economy.

Grid operators are most concerned with reliability, and they often overlook the climate and pollution issues that come from running coal and natural gas plants around the clock as baseload power resources.

While incredible technological advances in the ability to forecast weather and renewable output are happening today, there are still times when solar or wind output don’t match demand – which freaks out grid operators.

That’s where energy storage comes into the picture. Technologies like pumped-hydro storage or large battery systems can be paired with solar and wind to capture whatever power they generate whenever it’s available, providing grid operators with confidence it’ll be available when they need it to meet demand.

What’s EROI And Why Does It Matter?

As more and more renewables come online, large batteries have become more and more attractive as an energy storage option. But as with most developing technologies, they’re often expensive, and thus Stanford’s research focus.

EROI of battery storage for wind and solar

EROI of energy storage for wind and solar graph via Energy & Environmental Science

The Stanford scientists examined the energy return on energy investment (EROI) ratios of using several technologies to store solar and wind energy. The EROI calculation is relatively simple – the amount of energy produced by a technology divided by the amount of energy required to build and maintain a storage system.

“Batteries with high energetic costs consume more fossil fuels and therefore release more carbon dioxide over their lifetime,” said lead author Charles Barnhart. “If the battery’s energetic cost is too high, its overall contribution to global warming could negate the environmental benefits of the wind or solar farm.”

Based on this formula, many battery technologies may not provide a positive EROI when used for wind energy. “Both wind turbines and photovoltaics deliver more energy than it takes to build or maintain,” said co-author Michael Dale. “The overall energetic cost of wind turbines is much lower than conventional solar panel.”

Stanford’s EROI found the energy demands of solar power installations comparable to the energy demands of the five leading battery technologies. But wind farms, since they require less energy to build and maintain, significantly reduce EROI from 20-50% depending on the energy storage technology.

That’s a problem for wind power, because curtailment – shutting off the turbines when they’re generating too much power – only reduces EROI by 10% “For wind farms, the energetic cost of curtailment is much lower than it is for batteries,” said Dale. “It would actually be more energetically efficient to shut down a wind turbine than to store the surplus electricity it generates.”

But Hope Still Springs Eternal

But while that reality may be true, it doesn’t comport well with our need to get off fossil fuels to cut emissions and slow climate change. Fortunately, the Stanford researchers do see several options to make the EROI of energy storage via batteries work for both wind and solar generation.

Increasing battery life cycles is the most effective way to boost EROI, according to the study, but the goal is high. The Stanford researchers estimate batteries must endure 10,000-18,000 cycles to efficiently store energy on the grid – but conventional lithium-ion batteries only last 6,000 cycles and lead-acid batteries only 700 cycles.

Pumped-hydro energy storage performs best of all the available options, providing an EROI 10 times better than conventional batteries, but with limited deployment options. Other options like vehicle-to-grid technology also hold promise, according to the researchers, and could grow in scale as more electric vehicles hit the road.

Check out our new 93-page EV report, based on over 2,000 surveys collected from EV drivers in 49 of 50 US states, 26 European countries, and 9 Canadian provinces.

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About the Author

Silvio is Principal at Marcacci Communications, a full-service clean energy and climate policy public relations company based in Oakland, CA.

  • Tai

    Knowing that battery does not come cheap and the EROI of having battery does not looks good on graph. But we do not have actual figures showing that solar farm might be actually better without battery as the effort, energy , financial cost and carbon emission from the battery might actually be worse off. Wondering if you could share your figures on this issue.

    • Bob_Wallace

      We can start with the carbon footprint of the battery. From what I can tell the carbon comes from two sources – the electricity used in manufacturing and the petroleum used in extracting materials and transporting.

      As we green our grids and replace petroleum with electricity the carbon footprint of batteries decreases. A few years out the carbon footprint of batteries should be very low.

      Wind turbines and solar panels have already “greened” themselves. We have enough wind and solar on the grid to produce more electricity than we use each year to manufacture turbines and panels.

  • Matt

    Bob you amaze me that you have the patience to stand at the center of a storm of trolls and continue to shine information.

    • Bob_Wallace

      It’s not much different from teaching lower level university classes.

      The difference is that I can postpone my reply until I feel like making it. Can’t do that with the problem child in Whatever 1010.

  • Roy Wagner

    I consider the argument in the article above as to whether you should build a garage for your Bentley or your Cadillac?
    When it comes to energy storage this is the wrong argument.
    Most energy storage is unlikely to be installed at the same site as a wind farm or solar farm as it has several other practical uses.
    These make the storage installations location much more likely to be nearer the demand for quicker response times to local load conditions such as Voltage regulation, Peak usage etc.
    In this case you can consider the storage saving the electricity produced from a fuel burning source while you are using a fuel free source.
    Energy storage should also be valued on it’s ability to save hydrocarbons from being consumed and CO2 being produced.
    The more storage the less Peaker plants that are needed even more storage removes the need for spinning reserves.
    Energy stored in a battery is a form of chemical storage making hydrogen or synfuels is also energy storage. Pumped Hydro, CAES or gravity systems are potential energy storage.
    Renewables can use any of these forms of storage as can fossil fuel sources.
    It is a matter of perspective the main reason for energy storage is to reduce fossil fuel consumption not to store surplus energy from a wind farm.

  • Steeple

    Simply put, distributed solar generates at a time of day highly correlated to daily demand cyclicality, while wind is typically out of phase (and out of place) to demand. Bringing solar on to shave peak load needs while we balance the system on flexible nat gas turbines seems to be the best strategy towards reducing our overall cost of generation while maintaining reliability, allowing people to live with first world and not third world service, all the while preserving our fossil fuel resources. And if we reduce carbon emissions along the way, some people would be happy about that.

    • Bob_Wallace


      Natural gas is our most affordable way to fill in for wind and solar at the moment. That makes it possible to reduce coal use, replacing 100% coal with ~50% wind, 30% solar and 20% NG. Which greatly cuts our carbon emissions.

      With some luck we’ll have storage technology soon that will allow us to leave both coal and natural gas in the ground and do ourselves no further harm.

      • Steeple

        Bob, how many wind turbines would that take? The number a gazillion comes to mind, but I honestly don’t know.

        • Bob_Wallace

          I’ll copy in something I wrote a while back. It kind of goes past your question, but I think the land use interesting.

          And I used only 3 MW turbines. 7.5 MW turbines are now being tested and plans are made for 10 MW.

          In 2010, the US used 4,143 TWh (terawatt hours) of electricity. (11,300,000 MWh per day.)

          Since we’re just guessing what our future grid would look like, let’s assume we get 40% of our electricity from wind, 40% from solar, and 20% from hydro, geothermal, tidal, wave, etc.

          4,143 TWh x 40% / 365 days = 4,520,000 MWh needed per day from wind.

          The average wind turbine is around 3 MW in size and median capacity is now 43%.

          So, 3 MW x 24 hours x 43% capacity = 30.1 MWh per day from each 3 MW turbine.

          4,520,000 MWh / 30.1 MWh per turbine = 150,166 3MW turbines.

          The footprint of a wind turbine is typically around 0.25 acres. This includes the tower foundation, roads, and support structures.

          150,166 wind turbines x 0.25 acres = 36,040 acres required for our wind turbines.

          The land needed to install all those 150,166 turbines would take the space of about 2.4 Manhattan Islands, 1.4 Disney Worlds, or 0.0015% of the US.

          Of course we’d spread them out so they don’t bump into each other….

          Overbuilding would mean more turbines. Larger turbines would mean fewer. It might be that 150,000 could be pretty close to the final count.

          • fireofenergy

            Cut the capacity from 43% to like 32%, and add in an efficiency loss in the desired storage. Also, add in the fact that we WILL need to replace gasoline with electric (necessitating about 2x the present total electrical needs).

            Thus, based on your figures, we need at least 480,000 (150k x 1.33 for more accurate capacity factor x 1.2 for efficiency loss of battery storage x 2 for powering electric transport) and at most, 1.2 million such if molten salt and the steam generator is used.

            What would be cheaper, a million turbines and cheap molten salt and turbines, or far fewer turbines and more expensive batteries?

            Or simply re-developing the molten salt reactor?

          • Bob_Wallace

            Why would I cut capacity for wind farms when 43% is the current average and capacity is rising with new technology?

            Wind is cheaper than nuclear. That’s just a simple fact. Even paid off reactors are going bankrupt because they cannot compete with wind and natural gas. There is no possible way to build any sort of new nuclear reactor and be competitive.

            Additionally, solar prices are falling very rapidly. Utility scale solar in the US is already cheaper than new nuclear. Were we installing at China’s cost then utility scale solar would be competitive with paid off nuclear (the standalone reactors which are failing).

          • fireofenergy

            I’m under the impression that we NEED a five x buildup to make up for capacity loss (with solar), so assumed that wind would be better at about 30% capacity. It’s hard to believe that they can get that high! I hope it’s true because I would rather have wind and solar, than the Molten Salt Reactor, despite that the MSR is meltdown proof and has already been proven decades ago.
            When you say cheaper, you mean up to the 20% max grid limit (before storage is implemented on the very large scale. There is NO way that the physical design of a little MSR would cost more than wind, its backup and more backup for storage inefficiency. Period. In the future, if money hungry hands are not allowed to RAPE the promise of advanced machine automation, THEN you win this argument… And I really do honestly hope that is the outcome, because even though the MSR is the safest most efficient nuclear, running on thorium (search it), I’m still kinda afraid of it!

          • Bob_Wallace

            Don’t get hung up on capacity. It is what it is. The important number is $/MWh, $/kWh. We simply build what is cheapest.

            We’ve got all the rooftop and parking lot space we need for solar. We can spare a few Disneylands to build the wind we need. Don’t forget, we’re already using/screwing massive amounts of land for coal and uranium mining.
            It’s not an issue of how safe or unsafe nuclear might be. It’s the cost, pure and simple. Companies that own nuclear reactors are stating that new nuclear is too expensive to consider. Their new generation is wind, solar and natural gas.

            When grid ability to transition to wind and solar was investigated the acceptance numbers ranged from 25% (eastern grid, IIRC) to 35% (western grid) to 45% (Hawaiian grid). Since then we’ve increased the amount of natural gas generation on the grid and cut coal by over 10%. The NG is dispatchable which means 25% has risen appreciably.

            With more electric vehicles (EVs/PHEVs) coming on line the upper limit increases. We’re adding more dispatchable loads which will also raise the penetration numbers. And we’re closing reactors which will free up the existing 21 GW of large scale storage we already have.

            Storage for renewables is quite a distance away.

            Now, let’s look at this –

            ” There is NO way that the physical design of a little MSR would cost more than wind, its backup and more backup for storage inefficiency. Period.”
            Nuclear reactors are nuclear reactors. They are complex machines and are basically built by hand. (Even building a few hundred in a factory would still be mostly hand work. That scale production does not pay for automation.) And there is no rational explanation why small reactors would be cheaper, MW to MW, than a large reactor. In fact, the opposite holds since many systems would have to be replicated if capacity was split over multiple reactors.

            With molten salt reactors you’re just moving something other than water through the pipes. You’ve still got to build the reactor containment system, the steam generator, and all the plumbing to tie them together.
            Then, don’t forget, new nuclear would require new storage in most cases. The grid does not need more capacity. Capacity is needed during peak demand hours. We ran into that problem when we were building reactors back in the 1970s and 80s. Had to build 21 GW of storage to move late night nuclear production to the daytime where it was needed.

            Our grids are oversupplied during offpeak hours. That is why nuclear reactors are going bankrupt. You can’t turn off a reactor so the operator has to unload the power somewhere. The only way to do that on a grid is to undersell the competition. Since wind has no fuel cost and can sell for close to 0c/kWh nuclear pretty much has to give its power away, even pay the grid to take it.

            If you sell below operating costs for part of the day then you have to increase your selling price during the rest of the day to break even. The operating costs for a paid off reactor (one of the stand-alones), is running about 5c/kWh. If you have to sell half the time for around 0c/kWh then you’ve got to sell at 10c/kWh for the other half.

            Utility solar is now selling for under 10c/kWh. Natural gas combined cycle plants are selling for less than 10c/kWh. Nuclear is dead. And, remember, I’m talking about paid off nuclear plants. Add in 5c to 15c per kWh for loan payments and you should be able to see that new nuclear makes no financial sense.

            Wind, without subsidies, is selling for 6c. Solar, without subsidies, is selling for 10c and dropping fast. Natural gas, without subsidies, is selling for 7c. Electricity from the Vogtle plant now being constructed looks like it will be in the 12c to 15c range.

          • fireofenergy

            Convincing… but we need something as reliable and powerful as ALL the coal plants. “Global warming” may have lessened a bit, recently but excess CO2 is still not right.
            Nuclear is dead because of the fear and the non standardized, non modular, reliance on very high priced contractors. If we are to do nuclear, we must start from scratch and build the BEST type, 1,000 at a time. Even by hand, it would still be much cheaper.
            Nuclear is dead because of business (and nuclear) as usual.

          • Bob_Wallace

            A mixture of wind, solar, geothermal, hydro, tidal, biomass, biogas, natural gas and storage is every bit as powerful and reliable as all the coal plants put together.

            There’s one flaw in that mix – the natural gas part. But NG is simply a placeholder for better storage.

            In today’s America the movement away from coal will not happen if the cost is too high. Without including NG – at this specific point in time – we don’t have the financial package to push coal over the edge. If the cost of replacement is too high then utilities will just stick scrubbers on existing coal plants in order to comply with EPA regulations and keep on spewing CO2.

            Using NG is not what we would do if our goal was to slow/stop global warming. But at this time we do not have the collective will to make that our goal. Our nationwide goal. (Lots of us have it as a personal goal, but we don’t have control.)

            You’re arguing that nuclear would be cheaper. I just can’t see that. I’ve seen no credible person or organization claim that new nuclear could be brought on line for less than about 11c/kWh. I’ve seen informed, thoughtful people estimate the cost would be 15c/kWh or more.

            Wind is 6c/kWh and will drop before a new reactor could get built. (Remember, even the Chinese take six years or more to build a reactor.)
            Solar is now hitting 10c/kWh and should be fairly close to 5c/kWh six years from now.

            Geothermal is under 10c/kWh.

            CCNG is about 7c/kWh.

            Storage is running 6c to 10c/kWh.

            Biomass, in a converted coal plant would be under 10c/kWh.

            Those are all cheaper than the lowest estimates for nuclear.

            If you want to argue that nuclear could be built for less than 11c/kWh then you need to explain why it has not been done. No fair arguing that we can invent something that will make it cheaper, has to be done with the technology we have at hand.

            We have seen multiple open bids for new nuclear in the last few years. The submitted bids have run from 15c/kWh (UK) to 20c/kWh (Ontario, San Antonio, Turkey). If someone knew how to build cheap nuclear they could have stepped forth and turned in a sub-10c/kWh bid and gotten the contract. (None of the 15+c bids were accepted.)

            If the industry hasn’t offered to build for less than 15c then how could one possibly think that new nuclear could be built for less than 10c?

            You can find people who claim that new nuclear could be cheap. But the people who actually build nuclear reactors are not saying that.

          • fireofenergy

            Thanks for replying. I see, it’s about costs. LFTR will probably be more expensive than the advocates say. However, it does have the potential, in fact, a MILLION times more so than coal. Like I said earlier, it will take a lot of land to even come close to displacing all that coal, especially when we do cut NG as well.

            The way I see it is that eventually humanity will use NO fossil fuels because it will have to be that way. Either the excess CO2 would have fried the biosphere or it would simply be too high priced far after the peak. This is where I’m looking.

            However, you’re looking at the more immediate future. in which case I must agree. Switch to NG to reduce (slightly) the excess CO2, develop all the renewables and hydro.

            But I do NOT agree with biofuels. We need that to go back into the ground for obvious reasons and for the natural SEQUESTRATION of CO2. Sure, some wood for fireplaces, but even that should be limited as there are too many people because we need all the trees as well!

            A biofuels based economy would require on the order of TEN TIMES that of a solar economy! Thus, biofuels is just a waste of our collective efforts (although great for “backyard” projects). And solar would take hundreds of thousands of square miles (unless we scrap our already entrenched urban sprawl way of life for the most efficient “way” possible). This is acceptable in my view. I already did the math… solar WILL take at least 400,000 sq mi in order to power its storage, its inefficiency of storage AND to power 10 billion people. Albeit, for the least expensive steam generators from molten salt! The “battery” infrastructure would reduce such land requirements by half! But all the batteries on the planet could only store about ten minutes of the world’s energy needs, or so they say.

            If we rebuild in the most efficient way, we will need more coal and oil to do so (unless we actually do the the large scale solar and storage thing).

            Thus, I have, a long time ago, come to the conclusion that we must scrap anything that is lessor than solar, wind and hydro, and that we will need on the order of TEN times the amount of energy the world now requires in order build up all of China, India, etc, AND to have power to clean up the excess CO2 mess via the same kind of advanced machine automation needed to make cheap solar, wind and batteries.

            If it is not fission, then it will have to be fusion (which I have no hope in as it is too hard to contain 100,000,000 degrees). Or it will have to be space solar power (which requires MASSIVE amounts of cheap energy in order to overcome the Earth’s gravity well). If it is not any of these powerful options, then it will have to be very cheap storage and lots of land.

            Also, some countries will HAVE to resort to nuclear (or fusion or space solar), or be dependent on their neighbors. There is just no getting around that pesky intermittent and dilute nature of the renewables when there is simply not enough of that resource in the first place.

          • Bob_Wallace

            We need a non-fossil fuel option for some applications such as airplane fuel. Biofuel can provide that. Biofuel is unlikely to be a large contributor to our overall energy supply, but it can fill an important niche.

            Whether you or I think it best that our energy future be based wholly/largely on finances, that is what is going to happen.

            I can imagine that once the climatic problems get bad enough there will be political will to price carbon adequately to swing the transition away from fossil fuels faster. But that is not happening now, so it comes back to finances.

            You seem to continue to believe that nuclear is less expensive than renewables and/or that renewables are unable to power the world, to give everyone all the energy they desire. The facts simply do not support your beliefs.

          • Bob_Wallace

            “”Global warming” may have lessened a bit”

            No, global atmospheric temperatures have not been rising as rapidly as they had been. (Possibly due to strange ENSO behavior.)

            If you look at the temperature record for air, earth and ocean it’s clear that we heating things up quite nicely….

  • Paul D

    Based on the article content, isn’t the study somewhat limited in its analysis of the type of energy storage?

    Current battery technology must be a stop gap solution not a long term one. I don’t really view the use of current technology as being other than a test program.

    My favourite energy storage project/development is pumped heat storage as being developed by Isentropic.

    • Bob_Wallace

      There are multiple interesting storage idea such as Isentropic’s hot gravel system, but until they are actually in the field and producing real world numbers we can’t treat them as “real”.

      The developing storage solution that most interests me is Ambri’s liquid metal battery. The materials used, like Isentropic’s gravel, are really cheap and there’s apparently nothing in the system that would wear out. Extremely long cycle life.

      Isetropic has money to build a demonstration project. Ambri claims to be going into production in 2014. We might have very good news before long and if either of these works at the cost levels claimed then the math for store/curtail changes.

      I hope people realize that we already make the store/curtail decision and did long before wind and solar became part of the web. We have fossil fuel generation that runs only part time, some plants run only a few hours a year. And we have 21 GW of pump-up and CAES storage that was built decades ago. We’ve been making the “Build more storage?” decision for a long time.

  • RobS

    There seems to be a lot of misunderstanding of this study. What it shows is that renewables are getting so cheap, particularly compared with the costs of batteries, that for the cheapest renewables it is economically more efficient to install far more capacity then is needed so that at times of low output it is still adequate for demand and simply shed generation when it is then inevitably higher then required. The alternative of course is to install less and then use storage capacity to capture a smaller excess to fill in the gap when production is lower than demand. If the renewable generator is more expensive as is the case with solar vs wind then this effect is less obvious and at some cost point it is more efficient to store energy rather than overbuild. This is fairly intuitive, this study just quantifies it. One of the traps of a study like this is that it takes a snapshot in time and makes a conclusion based on it. The reality is that it is a highly dynamic situation with the costs of both renewables AND storage both falling rendering the break even point highly mobile. Furthermore these types of reports have a long tawdry history of significantly overestimating renewable costs as they usually gather their cost data from large government reports which are only completed every few years and are based on smaller surveys which themselves are often as much as a year old, the net effect being the pricing data is often at least 3-4 years old, a massive delay when one considers how far solar costs have fallen in the last few years.

    The details here are so fluid as to be fairly uninteresting, what is important is the concept that using storage for medium term power storage is not cost effective at present, short term frequency regulation is a different issue and requires a far smaller buffer being cycled more frequently maximising the economics. This may change as costs fall but at present the focus should be on maximising renewable penetration as we are nowhere near the point where intermittency is a difficult issue except perhaps in Germany.

    • Very good points.

      Also, the EROI of 8 for solar panels seems way too low. The consensus seems to be 18 months for the energy produced/energy invested break-even for PV panels. Now, with an expected 30 year lifespan (360 months), that would be an EROI of 20. I don’ think that installation and other factors could bring this down to 8.

      • RobS

        Doesn’t seem too far off. The NREL released a document which is now getting a little old which claimed solar’s energy payback is 2-4 years at present with an aim to get that down to 18 months.
        If it’s 3 years with a 30 year lifespan that would be an EROEI of 10, make it 25 years and your at 8.3. I think the number is pessimistic but its not out of the ballpark.

  • Matt

    Over build is only hard to understand when you consider the whole grid. Lets look a a simple case. Lets assume that we are on a island that is not connect to any other. During the windy part of the 2 turbines provide more than enough power to get us through the entire day. But during the less windy part of the year they we have extra at night but not enough during peak. So should we add batteries or another turbine? The study say that right now it is cheaper to add the extra turbine and stop them when they make too much power. Yes this is over simplified, it doesn’t worry about exact matching or phase regulation, where flywheels or batteries (both are storage) would help smooth things out. That is why GE put batteries inside their turbine towers so provide smoothing.

    Now if the study said, this means we should build wind/PV like mad and worry about the times when there is too much power later. I would agree. But again when there are time of day when the electric is almost free, then power shifting application will pop up to help absorb it. Its also why we need to get find a way to add externals into coal/gas so that when there are need you pay more and move your need to another time.

    • RobS

      I lived on a cruising catamaran for 18 months at one point. We used 240 watts of solar and a 300watt wind turbine for about 95-98% of our power needs. There were really only a handful of times we ran our engines for the battery charge. This experience helps one understand both the potential and the limitations of an intermittent generation grid with storage buffer and demand response. You simply learnt to use power when it was in excess by running the watermaker firing up the computer and HF radio to download HF radio email and a bunch of other high power usage activities. If you didnt take the opportunity with the batteries fully charged the wind turbine would simply freewheel in it’s non charging mode and you could literally see and hear the wasted energy. Similarly when production was low for a period you had two choices, progressive power down, turn off all unnecessary electronics and use only the LED light fittings (this was the very early days of LEDS so we had a few scattered around the boat) certainly not a time to run the watermaker. If this wasn’t enough (it almost always was) then you could fire up the engine with its high capacity alternator and add some charge from our diesel supply.
      This experience was certainly instructive in what’s possible, I have all the time in the world for those who argue based on the economics of such a system, it is undoubtedly a limitation, less so then many believe but an valid issue to be tackled nonetheless. I have no time for those who argue that it is not technically possible, it is, I have lived on a 95%+ wind and solar grid with storage and manual demand response, it has limitations, none of them insurmountable.

  • SecularAnimist

    The author says: “If true, this research could undercut one of the most promising
    opportunities to solve intermittency concerns from renewable power
    sources and better integrate wind and solar onto the grid.”

    I don’t see why this research “undercuts” anything. IF TRUE, then it simply shows that utility-scale battery storage is a more cost-effective match with solar power than with wind.

    So what?

    Wind without storage remains just as great as ever — and it really IS great, it’s a vast resource that can be quickly and inexpensively harvested to provide huge amounts of utility-scale grid power.

    And WITH battery storage, solar gets even better than it already is — especially distributed end-user onsite solar with distributed end-user onsite storage, both of which are plummeting in cost, and which have the advantage of being very easily “integrated” into the grid, since the grid simply sees them as demand reduction.

  • Bob_Wallace

    Just my personal observations about overbuilding vs. more storage.

    I’m off the grid. I’ve got 1.2 kW of panels in my yard. On sunny days, when the previous day has charged my batteries so that I’m just replacing what I used up after the Sun went down, I’m fully charged by 11 AM. I’m overbuilt by five hours for those days.

    There are other days when, while starting with the same battery levels, I won’t reach charged until 1, 2 or 4 PM. If I wasn’t overbuilt for 11 AM then I’d have to crank up the generator on the 1, 2, 4 days. And I’d have to run it longer on days that I get partially charged thanks to the “11 AM” overbuilding I have.

    Now that panels are getting cheaper I’m considering adding more just to avoid some of the generator hassle. Adding panels is likely cheaper than adding storage given today’s battery prices.

    (Now if EOS Systems was selling their zinc-air to individuals….)

  • Ivor O’Connor

    Thank you Silvio Marcacci for doing the best write up I have seen on this Stanford FUD.

  • mikgigs

    My opinion is that this article is pretty good but some weaknesses are revealed. The author speculates about “the relative unpredictability of the wind blowing and the sun shining”. In fact, if a wide spread random output system is stated(e.g. wind turbines scattered on big land), then the system would converge to non-random low-pass signal shape of energy output, which is highly predictable and easily tuned to stable level, by simply switching-off a percentage of such turbines( I would refer to the book of Statistical Signal Processing by Kay), thus more turbines – better stability. Moreover, chemical batteries(like li-ion) are pretty not-attractive solutions for such problems, author should become aware about other non-chemical battery sources: “flywheel energy storages”(e.g. Beaconpower) which are perfect match for wind-turbine backup, power-to-gas solutions and pumped-storage hydroelectricity(as already mentioned), molten-salt battery pools, and etc.

    • Ivor O’Connor

      I think the article was overly complex to hide the fact he was stating something that did not add up. As you and Bob have pointed out the energy is not binary and highly predictable.

      Take a look at the group who funded his studies. Here is the URL.

  • Aren’t they already using the stored salt system like that solar plant in Spain that can go full power with no sun for 15 hours? Anyone know the EROEI on the molten salt systems? thanks.

    • Ronald Brakels

      Well, storage losses are only about 1% for molten salt setup so it would all depend on the efficiency of the generating setup. If its efficiency is a third then about 1 joule of electrical energy would be obtained from 3 joules of stored thermal energy. But I don’t think people are very concerned about EROEI, I think they are generally more interested in whether or not they can make a buck.

  • Shiggity

    Pigeon holing storage into one type of energy source is looking at the problem wrong. Batteries don’t care what kind of energy they store, their location is what’s important. This looks at batteries at the utility level, they should be looking at the substation level, the bottleneck between distribution and generation.

  • Dan Hue

    If they mean that it would be better to overbuild than to store from an EROI standpoint, that might make some sense (mathematically), but the main issue is reliability, not GHG emissions. That’s because overbuilding does not solve the intermittency problem. And do they factor in the emissions of whatever replaces wind power when the wind does not blow and there is no storage?

    • Bob_Wallace

      Over building makes wind and solar more reliable. It’s not binary, we don’t have only conditions of “enough” wind/solar or “no” wind/solar, there are all sorts of levels in between enough and no. There are times that the wind is blowing 90% of “enough” or 70% or 40% or 15%, etc.

      The decision is whether it is cheaper to overbuild so that during the 70%/whatever you have enough or whether you fill in with stored or dispatchable energy.

      If it costs 4c/kWh to generate wind electricity and 10c/kWh to store it, then over building, to some level, is going to make financial sense.

      • Dan Hue

        I guess I don’t really understand the notion of “overbuilding”, when renewables still have such low overall penetration. Before we even start considering storage, we should improve grid interconnection (to smooth RE supply) and more flexible demand (to more closely align RE supply and demand).

        But I see your point though (and that of the article)… Even in that ideal situation where we have optimized the generation of RE over the largest integrated area possible, there could be times when actual renewable power generation is not enough, and in that case, over-sized wind farms working at (say) 50% capacity could be better from an EROI than normal-sized ones plus some storage.

        • Bob_Wallace

          Where we are and where we could go are two different issues. Clearly we don’t need storage (on a large scale) yet and neither are we anywhere close to making a decision about overbuilding.

          What we’re doing now is considering how we could solve our carbon problem with the technology we have. And that leads us to a discussion of where we might best put our efforts to find new technological solutions.

          Overbuilding generation, at some scale, would be cheaper than installing storage, given the current cost of generation and storage. A major improvement in storage would change the math.

          We can look at the Budischak, et al. paper and be assured that we could get off fossil fuels using current technology and do it for an acceptable price. With today’s storage options it would mean a fair amount of overbuilding. Cheaper storage would decrease the need to overbuild.

      • marque2

        First off wind power is more like 25 cents per kwh plus an additional 3 cents for the Natural gas backup. Natural Gas is generated at 4 cents per. Which already indicates to me that the wind is doing more environmental damage than the NG. But lets overbuild. Wind requires 80% backup so to get a stable wind system, over projected windy hours, you would need to build 5 units in disparate parts of the country – they can’t be right next to each other since if the wind stops blowing then all 5 units would stop. So to do this the energy would cost us $1.25 per kwh, vs $0.28 for the wind plus backup vs $0.04 for natural gas. Don’t know how I would survive Texas summers paying $1.25 per kilowatt hour for my air conditioning. Solar is worse requiring some 13x backup.

        If you really want to go eco nuts and folks are willing to pay 5x as much for electricity that is intermittent, than it would actually be much easier to restructure our society so that we just don’t use power when it is not available, That 20% of the time we are undergenerating power, call a no work day, don’t wash laundry or dishes that day – wait a few days until conditions improve and then do your stuff. It would be inconvenient, and we could have upset folk who can’t watch MSNBC – but we would all survive.

        We could also go eco like they do in Europe by cutting down all the forests and burning them. We could use Mesquite and Hickory instead, and hold a BBQ while generating our eco power.

        • Bob_Wallace

          I don’t know where you are from but here in the US the average selling price of wind during 2011 and 2012 was 4c/kWh. Add in the federal subsidy and it tells you that wind electricity is being generated for about 6.2c/kWh. That’s an ‘all in’ price that includes not only the normal LCOE stuff but also real estate, transmission, taxes and profits for the wind farm owners.

          Wind certainly does not require 80% backup in the US. That’s a load of horse poop.

          All generation requires backup. We have to be able to jump in with alternative generation when a coal or nuclear plant goes offline. Wind and solar are no different.

          Wind and solar are not ‘always on’ generation. They are available at some times and not at others. That does not make them more or less expensive. They are what they are.

          Wind is now one of our two cheapest ways to generate electricity and solar is getting there. That means that the smart move is to use them when they are available and then look for the least expensive way to fill in when they aren’t.

          We have enough dispatchable NG and hydro on our grids to allow us to use wind and solar for 25% to 45+% (depending on grid) of our total capacity. As we make the grid smarter and add EVs/PHEVs those numbers will rise.

          When we get to the “25-45+%” point then we will need to add more storage or fill-in. We are years from that point.

          Oh, I just noticed that you’re in Texas. No one has told you that your electricity prices have dropped because you’ve got all that sweet, sweet wind on your grid?

          Consider yourself told.

          • A Real Libertarian

            “wind electricity is being generated for about 6.2c/kWh”
            But that’s using the Commie doctrine of math!
            All freethinking individualists use bellyfeel, it’s the only non-mentally ill way.
            Any other thoughts are Free-market hating doubleplusungood!

          • Bob_Wallace

            “All facts that don’t support our beliefs are to be quickly discarded.”

          • A Real Libertarian

            Winston, it is time to go to The Place With No Darkness.

  • Bob_Wallace

    “the amount of energy produced by a technology divided by the amount of energy required to build and maintain a storage system”

    The decision will not be based on EROEI. It will be determined by the value of energy at a particular time. A lower EROEI simply means that it will cost more to produce/store that energy. Since we need energy when the wind isn’t blowing and the Sun isn’t shining we’ll pay what it takes.

    There is a decision to be made as to whether it makes economic sense to build more capacity or to build storage. I’m off the grid, it was a lot cheaper for me (even with the price of solar panels of ten years ago) to install a lot more panels than I need for sunny days than to purchase more storage or use more backup generation.

    As long as storage stays as expensive as it is it will make sense to install more wind/solar capacity and curtail unneeded production in order to avoid spending more money on storage. Wind, being cheaper than solar, lends itself to overbuilding more than does solar. As the price of solar drops it will make sense to overbuild solar to a larger extent. As the price of storage drops the math will push toward more storage and less capacity overbuilding.

    • Ronald Brakels

      Could you explain this? All else equal, if Bob were to connect his home to the grid would this increase CO2 emissions?

      • Bob_Wallace

        Yeah, I want to hear that answer, or at least Bret’s version.

        I know what the actual answer is.

        • Ivor O’Connor

          I wish I could have read the original comment before it got deleted…

          • Bob_Wallace

            It was a claim, essentially, that the only way to get rid of coal is for everyone to go off grid.

          • Ivor O’Connor


          • marque2

            That is basically what had to be done – and then one would need to deal with local power shortages as they come up. No power from 12 minight to 6 am – well have battery backup in your clocks and don’t plan yo do wash then. Cloudy day – wait till tomorrow to wash clothe or do dishes. It can be done – it is just a bit more inconvenient. Those who put solar up and don’t pau utilities any more and yet rely on the 92% backup the utility has to provide anyway are really taking money from the rest of us and esp. the poor.

          • Bob_Wallace

            That’s a pile of crap.

            You expect everyone to stop their lives when the Sun doesn’t shine enough. To let the food in their freezers spoil. Those who need assistance breathing to just stop until the Sun comes back out. Manufacturing to turn on and off with the Sun.

            “Don’t have your heart attack between mid-night and 10 AM. We can’t do anything for you until it’s bright outside.”

            What you describe is a hair shirt existence that most people would not be willing to live and for which there is no need to live.

          • A Real Libertarian

            You know he’s just going to say “that’s my point Dur, Hur, Hur” right?

          • marque2

            It would be easier to do than what what I suggest than overbuild by 5 – 13x depending on technology It would be completely unaffordable, and they you still have the issue that the sun doesn’t shine and the wind doesn’t typically blow typically between 10pm and 6 am every day, just about everywhere so we have to implement some form of my solution anyway. And it is a solution in search of a problem as well (it looks like we have 1000’s of years of natural gas available to us, with new technologies to mine it from ice along the continental shelves) And IPCC in their new report is about to admit that temps aren’t going up much either (in the last three years they have been falling)

            So back to intermittent power, Fridges can last 5 – 6 hours in the night without cooling. – But if we do some planning – add extra insulation, make some extra ice during the day – it shouldn’t be a problem. As for TV, read a book with a manually charged LED flashlight, as for laundry and dishes they can wait a day. Warm dinner, that can be for tomorrow, tonight we eat from cans. Like I said it would be intermittent, but it wouldn’t kill us.

          • A Real Libertarian

            “Like I said it would be intermittent, but it wouldn’t kill us.” – You now.

            “Don’t know how I would survive Texas summers paying $1.25 per kilowatt hour for my air conditioning” -You 20 minutes before now.

            Let me guess, time is an “eco nut”?

            P.S. Called it!

          • marque2

            I have been very consistent in my argument. No it would be difficult to survive without air conditioning, however, if it is just once in awhile it can be done. Good example 2 nights ago my air conditioning went out. It was 88 degrees outside at 10 pm. It was fixed the next day and I am enjoying the cooler air.

            I did manage to survive.

            However to make prices go up 25 fold would make air conditioning affordable all the time. That would cause me to move out of this apartment anyway, and possibly even out of Texas

            As a libertarian, you should be against all this garbage and just want the cheapest power to prevail. And that is what I want as well. Please note both situations I presented were hypotheticals based on others not completely thought out arguments. To which I now now add your comment.

          • A Real Libertarian

            I’m not the type of libertarian that shouts “all power to the corporations I own”.

            I’m the type of libertarian that stands behind those types sharpening my knives and whistling Le Internationale i.e. a real one.

            P.S. Still insisting math is liberal conspiracy to make you wear socks and sandals I see

          • Ivor O’Connor

            I being a real libertarian figured I had best look this “Le Internationale” up.

            May Gary Johnson be our president in 2016!

          • A Real Libertarian

            He supports the FairTax.
            I absolutely refuse to support anyone who goes that deep into Orwellian Newspeak.

          • Ivor O’Connor

            To be honest I have no idea what FairTax is or why it is Orwellian Newspeak. This is not the right place for these sort of discussions though. I’d like to continue this and educate myself so if you have a site where this sort of thing is discussed and can put the URL here I’ll head over to it.

          • A Real Libertarian

            Note the 23% rate is actually a 30% rate using earth math.

          • Ivor O’Connor

            Please go elsewhere. I don’t appreciate reading your spam.

          • A Real Libertarian

            “you should be against all this garbage and just want the cheapest power to prevail”

            I wonder which that is:

            Candidate A: Hi, it’s been 60 years, we need more subsidies. Oh thanks for paying for fixing any of my screw-ups, K THX BYE.

            Candidates B: Hi, it’s been 100 years, we need more subsidies. Oh we want you to invade this country and give us immunity to these laws, K THX BYE.

            Candidates C: Hi, it’s been 15 years, we need less subsidies for the next 5 years, and then we don’t need them anymore. Oh and in 2 years we shouldn’t need subsidies for our other stuff either. Pleasure doing business with you (reaches out hand for a shake).

            Now bachelorette who do you choose? (theme song from The Dating Game.wav).

          • marque2

            How bout candidate D, we are currently providing NG and getting almost no subsidies – In fact we are forced to pay more in taxes than other corporations.. Our product will be available for 100 – 3000 years depending on projections and technology estimates.

            Hmm guy C, I see you destroyed half of China with tailings from your product, and you claim its green.

          • A Real Libertarian

            “destroyed half of China with tailings” oh yeah that was solar power and not coal at all.

            You’re not fooling anybody with that cra- hey wait a minute “we are currently providing”? “we are forced to pay more”? “Our product”?

            You’re Candidate B! Wow, do the guards monitor your internet usage on Death Row there Rodney Alcala?

            I mean you even identified yourself as Bachelor #2. It doesn’t get more obvious then that.

          • Bob_Wallace

            There is absolutely no way we have “1000’s of years of natural gas”. We probably have only a few decades at the rate we are now burning.

            And this is a load of crap – ” And IPCC in their new report is about to admit that temps aren’t going up much either (in the last three years they have been falling)”

            It’s just ignorant. Global temperatures have not been falling. Near Earth atmospheric temperatures have been rising much slower than they were a few years back, but at the same time extra heat continues to be stored in the world’s oceans.

            Right now we’ve been in a neutral/La Nina ENSO condition for a number of years. Assuming we see another El Nino event there is a tremendous amount of heat that is going to be burped up by the oceans and we’re going to experience some very hot atmospheric temperatures.

            Intermittent power would kill people and kill the economy.

            What a “rugged individual” can tolerate would not work for the majority of people.

          • Bob_Wallace

            For some reason my image didn’t show up.

            Take a close look and see that the globe has not been cooling.

            edit: OK we’re experiencing a Disqus failure….

          • marque2

            You are not keeping up with the latest in technology. We probably have 100 years available with traditional on land side drilling and fracking – though that figure seems to be going up daily. And we have new technology just being developed to harvest burning ice. The technology has already proven feasible, when it comes down in price we should have 1000 – 3000 years of methane available. And possibly infinite since this burning ice source is constantly being replenished.

            And if we run out of Natural Gas in 100 years as you say, and assume we run out of oil in the same period, then using gasification and liquefaction technology we have an easily available supply of coal which will last 600 years as well. Note that gasification technology was developed some 350 years ago. liquefaction has been used at least since WWII and is the primary source of liquid diesel and gas in South Africa. It is also used to create Jet fuel for the Air Force – so it isn’t pie in the sky technology.

            There is no reason, except if you pray to the church of global warming to – at this point put up windmills and solar panels that cost from 5 to 25 x the cost of our conventional power, except in very specific and local applications. Maybe in 100 years when things have been figured out, and we are technologically capable of using much less energy anyway – then this alternate stuff will be feasible.

          • A Real Libertarian

            You know, for someone who says science will solve all our problems you really don’t know how it works.
            HINT: “Renewable energy is far too expensive according to the latest numbers just in from the University of My Colon” = not science.

            “The world has warmed a lot since we started pumping Carbon into the atmosphere, Carbon Dioxide is a greenhouse gas, hmm I think there might be a connection here, we should test it” = SCIENCE!!!

          • Bob_Wallace

            Luckily there are fewer and fewer of you people as time goes along. You deniers are rapidly becoming irrelevant.

            You probably should go elsewhere with your continued lies about the cost of renewable energy. We simply don’t have tolerance of that sort of stuff here.

            The world is rapidly moving away from fossil fuels. Coal first, then gas. Live with it.

        • Bob_Wallace

          And to furnish the actual answer – were I to connect to the grid my carbon footprint would diminish.

          I’m making a guess with which I’m fairly comfortable – that the carbon footprint of my gas generator is considerably higher than the carbon footprint of a coal plant or natural gas plant.

          Even hooking up to a 100% fossil fuel grid for my last bit of power would be cleaner than staying off grid.

          And when’s the last time anyone saw a 100% fossil fuel grid?

          • Ronald Brakels

            And you’d be sending your excess solar electricity into the grid for others to use. Electricity that displaces fossil fuel use.

          • Bob_Wallace

            Yes. I could pretty much eliminate fossil fuel use by another household.

          • A Real Libertarian

            Plus Montana has net-metering.

    • Ivor O’Connor

      Have you noticed the author’s funding comes from the four largest oil and nuclear companies in the world?

      • Bob_Wallace

        From your link I don’t see the nuclear connection. I saw two oil connections.

        Perhaps you’re calling GE a nuclear company, but GE is pretty heavily into renewables as well.

        • Ivor O’Connor

          Yes, when I think of nuclear I always think of GE.

          • Bob_Wallace

            For me, GE is a company that used to be more heavily involved in nuclear but is now building a lot of wind turbines and recently developed gas turbines optimized for use with wind and solar energy. And a company that was starting to get into the solar panel business before prices collapsed.

            ExxonMobil and Schlumberger, sure oil.

            GE and DuPont, seems like you’re concentrating on part of their activity and ignoring the rest.

          • Ivor O’Connor

            I still have my reservations. I see this article as little more than FUD. A way of pandering to those monopolies paying for his work.

          • Bob_Wallace

            I see the research as research. There’s information there.

            I think we make too much out of EROEI as we move more and more away from fossil fuels. EROEI is important with fossil fuels because we’re using up a limited energy source.

            As we move to wind, solar and other renewables there’s no practical danger of using up our energy supply. And increased energy use has little impact on carbon output. The energy input is only important to the extent it drives the final price.

          • Ivor O’Connor

            I would agree if he had said that. However his emphasis was on EROEI as if it mattered in this situation. Every talk show host will now take the title of his article to convert more neanderthals to a point of view against renewables. There was no reason for this author to stop where he did instead of taking it to the logical conclusion. So no I don’t see his paper as research.

          • marque2

            He is much bigger into renewables because with government subsidies it is much more lucrative. They even made NBC .

        • Ivor O’Connor

          ExxonMobil The world’s largest publicly traded international oil and gas company.
          GE: The world leader in power-generation technology and services.
          Schlumberger The world’s leading oilfield services technology company.
          DuPont Providing world-class science for the global marketplace since 1802.

          Yes. I think of GE as a nuclear company. And DuPont as an oil company of sorts.

    • Ivor O’Connor

      Very nice summation of the relevant facts.

  • Wayne Williamson

    I think that Stanford missed this one…storage is storage…whether its solar or wind or peak power from fossil or nuke.

    • Wayne Williamson

      I do have to agree on the number of cycles thingy…..

      • Steven Sullivan

        Wayne it depends on what technology was studied. No serious storage developer is talking about using li ion batteries for peak demand nor is their ready evidence that they last 6,000 cycles but you have flow batteries that have achieved over 25, 000 cycles which have been running for over 25 years

    • Bob_Wallace

      I think what they are reporting is that 1) it makes most sense to store the cheapest input rather than the most expensive input and 2) sometimes its cheaper to add more generation than to add storage.

      That’s from a financial consideration. And then we should also look at the lifetime carbon footprint for generation and storage. But from a practical level unless we become willing to price carbon then it’s all going to come back to cost of generation and storage. EROEI plays a role only in that energy has a cost that flows to the bottom line.

      • Matt

        YES!, what they are saying it is better to build extra turbines and turn them off at times, than to build turbines and batteries. But as “normal” they don’t include the benefit of turning off the coal and its free externals.

      • Ivor O’Connor

        Did you mistakenly get that backwards? Did you mean to say instead that it makes the most sense to store the most expensive rather than the least expensive?

        • A Real Libertarian

          You store the least expensive so even with the cost of storage it’s still cheaper then whatever is being generated now.

          • Ivor O’Connor

            As opposed to building double of the least expensive since that would be more cost effective?

            And the author of this article did say it makes sense to not store the cheaper wind but to store the more expensive solar. So if I understand this right Bob is disagreeing with the author…

          • A Real Libertarian

            First you overbuild and when the diminishing returns problem becomes too big, then you build storage.

          • Ivor O’Connor

            So then Bob got it wrong. I’m hoping I’m the first one who has ever corrected Bob on a renewable energy topic.

          • Bob_Wallace

            I might have gotten it wrong. Here’s my thinking…

            Wind at 4c.
            Solar at 8c.
            Storage at 10c.
            Stored wind = 14c.
            Stored solar = 18c.

            Cheapest to use wind and solar direct and fill in with stored wind.

            In practice we’d probably store both wind and solar in order to cycle storage more frequently and get a quicker return on investment.

            (And if I’m still wrong you certainly won’t be the first to catch me out. ;o)

          • Ivor O’Connor

            You are resorting to economics that make sense rather than the EROI the author’s paper uses.

            If you use economic sense you have to toss his paper. However if you are talking EROI and paraphrasing the author then it is just the opposite.

            Since I am not going to get a cookie out of this I’ll quit now. And continue to try to make sense out of the lyrics from “le internationale”

          • Bob_Wallace

            Yeah, I think the EROEI argument isn’t very important. Energy invested is going to be reflected in final prices for both generation and storage.

            The carbon content of the energy (EI) is somewhat important but will be come less important as the grid reduces its carbon component.

            The solution, in my thinking, is to build clean generation and storage as quickly as possible in order to stop the 24/365 use of fossil fuels for electricity. If our immediate least expensive route is a bit more carbon intensive that will be more than offset by getting fossil fuels off the grid sooner.

          • Ivor O’Connor

            I’d like to use those prices in the flame wars I participate in. Have you got references so I can read, understand, and then use to make myself into a flame god?

          • Bob_Wallace

            Wind –

            “The prices offered by wind projects to utility purchasers averaged $40/MWh for projects negotiating contracts 2011 and 2012, spurring demand for wind energy.”



            $40/MWh means $0.04/kWh. Add back in the $0.022 PTC and it’s $0.062/kWh.

            This is a low number. It’s not just the LCOE of wind. It includes real estate, transmission, taxes and wind farm owner profits. It’s the “delivered to the door” cost of electricity, not just the generation price.

            I’ve read a couple of comments lately from people in the utility business who report that PPA for wind are being signed for ~2.5c/kWh in the Midwest. Add in the subsidy and that’s 4.5c/kWh wind. They couldn’t report detail as that was privileged information.

          • Bob_Wallace

            Solar –

            I’m doing a big ‘notes drop’ here. If something doesn’t make sense post back and I’ll try to clarify.

            Here’s the very, very, very big number. China seems to be installing utility solar at $1 per Watt.

            City of Roseville, CA 7.4 Cents

            “Roseville Electric purchased 325,000 MWH of renewable energy for $24 million for 10 years. The contract cost $6.5 million less than similar renewable energy purchase offers in 2012. “

            First Solar Farm in Kern County


            Palo Alto 6.9 Cents

            The price is an eye-opening 6.9 cents per kilowatt-hour for the 30-year PPA.

            “Try building a new nuke or coal plant at that price,” was Adam Browning of Vote Solar’s take on the number. The price compares favorably to the typical market price referent and would seem to be able to take on prices paid for natural gas or wind. The projects still include the 30 percent federal Investment Tax Credit.

            The utility calculates the impact of its renewables contracts to be in the range of 0.11 cents per kilowatt-hour compared to conventional generation. The math looks to adjust for time-of-delivery, transmission costs, and capacity value.

            6.9 cents includes 30% ITC subsidy. Without subsidies the price would be roughly 10 cents per kWh.


            Last week, the San Jose municipal authority wrote contracts for 80MW of solar PV at 6.9c/kWh, which after a 30 per cent investment tax credit works out to be around 10c/kWh.

            Randolph says he has just approved more contracts for distributed solar systems of between 3 and 10MW in and around the same price. “I just signed off on a couple of contracts and they are competitive with fossil fuels,” he says.

            The other point of note is that California has not had to add to fossil-fuel generation capacity to support renewables. About 10GW of old, inefficient gas-fired generators will be closed in coming years for environmental reasons– these are mostly 50-year-old generators which use sea-water cooling through a method known as “once-through cooling”. Randolph says these will be replaced by newer gas turbines that can provide the flexibility to respond to renewables.

            Storage though will be critical, Randolph says, especially as the penetration of renewables goes beyond 35 or 40 per cent. “If we want to be doing it and have it being environmental meaningful, we will need storage. If you doing that (filling in the gaps) with gas, you are not getting an environmental benefit.”


            New Mexico 5.8 cents

            Adding in state (2.7 cents ) and federal (2.3 cents) subsidies makes it about 10.8 cents.


            UK Solar Farm at $1.59/Watt

            The site near Leicestershire in the English Midlands is now the location of Britain’s largest solar farm. The facility is 34 megawatts in size and will prevent the emission of approximately 170,000 tonnes of CO2 over its lifespan, which is equivalent to shovelling about 58,000 tonnes of coal back into the ground.

            The solar farm cost just over one pound a watt or $54 million. That’s in either Australian or US dollars as they currently both convert into exactly the same number of British pounds. (No doubt a fun day for currency traders.) This gives a cost of $1.59 a watt and according to a report commissioned last year by the British Government’s Department of Energy and Climate Change, it is 20% less than their figure for large scale solar in 2012.


            South of Rome for $1.20/Watt

            Deutsche Bank said that although the market in Europe had contracted, at least one third of new, small to mid size projects were being developed without subsidies. Multi-megawatt projects were being built south of Rome for €90c/W. This was delivering electricity costs (LCOE – with 80 per cent self consumption) of around €80/MWh (€8c/kWh)

            Deutsche Bank said that although the market in Europe had contracted, at least one third of new, small to mid size projects were being developed without subsidies. Multi-megawatt projects were being built south of Rome for €90c/W. This was delivering electricity costs (LCOE – with 80 per cent self consumption) of around €80/MWh (€8c/kWh)


            €90c = $1.20

            China $1/Watt

            “Yingli chief strategy officer Yiyu Wang said that project costs for its current pipeline of 130MW in utility-scale solar projects in China are about $1.03-$1.05 a watt.”

            “Wang suggested that Yingli would generate a return in the “higher mid teens” for these projects. “


            Unsubsidized Solar $1.43/watt

            A completely unsubsidized 250 MW solar energy project is currently being developed in the north-western region of Cádiz, Spain — near the town of Trebujena.

            The €275 million project will be built over a period of 2–3 years in five separate phases of 50 MW each. The first phase is expected to be connected by the end of 2015, and the final phase by the end of 2017.

            Once completed, the solar park will feature somewhere around 90,000 PV panels, which will generate about 420,000 MWh a year. That’s enough to power around 117,000 homes in the region, according to Tentusol.

            250 MW for €275 million.




            In the sunny Southwest. that would mean electricity at less than $0.06/kWh.

            Australia Rooftop As Low As $2.Watt

            Updated monthly under “Price” on left margin.


            Germany Solar System Average $2/watt

            Average system price in Germany. Includes utility, commercial and residential.

            Mai 2013 € 1.570


            $1.55/watt in India

            The solar park will be located in the Ramanathapuram district of Tamil Nadu. This solar park is expected to attain 70 MW of capacity by January, and the full 100 MW goal by April 2014.

            A crore in South Asia is 10 million. So the report says the project will cost 9.2 bn rupees, or $155 million, at $1.55 a watt.


          • Ivor O’Connor

            “I’m doing a big ‘notes drop’ here. If something doesn’t make sense post back and I’ll try to clarify.”

            It will take me time to assimilate. I’m copying it over to google docs.

          • Bob_Wallace

            I just ran some LCOE costs for Utility Solar. I used the EIA’s
            6.6%, 30 year financing and 0.9c/kWh O&M.

            ( )

            I compared the almost-sunniest parts of the lower 48 states (SW) with the almost-least-sunny parts (NE). Death Valley and the Seattle coast are not included.

            ( )

            At $2.10/W (US 2nd Qtr, 2013 Avg) = 8.9c/kWh in SW, 11.5c/kWh in NE.

            At $1.50/W (Europe Price) = 6.6/kWh in SW, 8.4c/kWh in NE.

            At $1/W (China Price) = 4.7c/kWh in SW, 5.9c/kWh in NE.

            US 2nd Qtr prices are generated by Greentech Media.

            ( )

            These price do not include subsidies. I think we can safely say that utility scale solar is being installed in the US right now for 9c to 11.5c/kWh. And as we catch up with Europe and later with China we should see utility scale solar for 5c to 6c/kWh.

            These prices do not include land costs, transmission or solar farm owner profits.

            LCOE is strictly the cost of generating power.

          • Bob_Wallace

            Storage –

            A Swiss report says 3 to 6 cents per kWh for pump-up if it is being cycled frequently. In use at least 1,000 hours per year. About 3 per day, which should be easy.


            Vanadium flow batteries are apparently about 8c/kWh, but I have no link.

            In the video on their link EOS Systems claims 10c/kWh for their zinc-air batteries.


            Storage costs are hard to find. Partly because storage is a very immature field and partly because cost jumps all over the place based on cycles/time.

            Any price info that anyone has will be appreciated. I’ll add it to my notes so that we can keep on top of where the market is headed.

          • Bob_Wallace

            All we can do at the moment is to understand the concept.

            We’re years from needing large scale storage. We can install 5+x more wind and 10+x more solar before we need to concern ourselves with storage. As we add EVs to the grid those numbers go higher. And as we add dispatchable loads the numbers go higher still.

            Who knows what the price of wind, solar and storage will be five years from now?

            Right now wind is much cheaper than stored wind, so if we were at the saturation point we would be better off building more wind and curtailing. But who knows what the math will be. What if something like Ambri or Isentropic bring really cheap storage?

          • Ivor O’Connor

            I agree with all that. As always. However I want a cookie for spotting you accidentally wrote point 1 backwards. I want my cookies now!

          • Bob_Wallace

            Not disagreeing with the paper. Just putting the paper into a larger context. At least the context I see.

            We have a limited amount of money that can be spent for wind/solar/storage. Spend the money in a way that gets the most fossil fuel use off the grid as quickly as possible.

            If the choice has a bit higher carbon footprint that is almost certainly going to be offset by a sooner/larger reduction in fossil fuel use.

      • Bob_Wallace

        If people aren’t familiar with it, I’d highly recommend giving Budischak, et al. a read.

        “Cost-minimized combinations of wind power, solar power and electrochemical storage, powering the grid up to 99.9% of the time”

        They take four years of minute by minute load data from a very large grid and calculate how to run it on (almost) nothing but wind, solar and storage. They take current (2008) and projected (2030) prices and puzzle out the best mix of overbuilding and storage.

        There’s is, of course, a worst case scenario. Add in hydro, geothermal, tidal, residual nuclear, load-shifting and power trading with adjacent grids and the job gets much easier. But even doing it the hard way they find it affordable.

        (At least read the main ideas, you can jump over the details.)

        And real world prices are even cheaper than what they used. We’ve already met and exceeded their 2030 projections.

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