Clean Power

Published on June 18th, 2013 | by Guest Contributor


Interview With Maxwell Technologies: Ultracapacitor-based Energy Storage System

June 18th, 2013 by  

This post first appeared on San Diego Loves Green
by Roy Hales


A week ago, Maxwell Technologies announced they had been “been awarded a $1.39 million contract by the California Energy Commission’s Research and Development program to fund design and integration of an ultracapacitor-based energy storage system with Soitec’s CPV system located on the campus of University of California, San Diego—one of the nation’s greenest universities— and a second commercial scale system at Soitec’s solar power plant in Southern California.” This project was to start immediately and run through November 2015.

I seized upon the opportunity to email Maxwell some questions about the future of energy storage. Shaw Lynds, the senior systems engineer at Maxwell,  responded. Note that Mr Lynds says that while small micro-grid solar systems may soon be able to operate without a back-up system, it is still too expensive to develop an adequate energy storage system that would allow the grid to run 100% on solar energy. That is why they are focusing on ironing out “fluctuations of up to 5 minutes.” Yet it would seem almost inevitable that some year, in the not too distant future,  solar energy will be able to supply all of our power needs.

Q.  To what extent will the technology that you and Soitec are working on compensate for the fluctuations in solar energy?

Our goal is to completely eliminate output fluctuations of less than 30 seconds and provide significant smoothing of fluctuations of up to 5 minutes.  The goal of this demonstration is that show that solar can achieve high penetration in the grid without need of large amounts of spinning reserve to keep the grid stable.

Q. Do either solar or wind energy have problems with power surges and does your technology eliminate this problem?  

Both of these technologies are vulnerable to power surges, however this is outside the scope of what this project plans to demonstrate.

Q. What part of the work will be done of the UC San Diego campus? 

Our partner Soitec currently has a 22kW CPV tracker system located on the UCSD campus that has been running for several years now. Under this project we plan to add 2.5 kWh of ultracapacitor energy storage to that system to demonstrate the large benefits that even a small amount of energy storage can add to a solar installation.

Q. Can you give an a guesstimate of how long it will be before solar energy can be stored for weeks? (Two years? Five years? Ten years?) 

5-10 years at minimum before it is economically viable to store energy on these kind of time scales.  This is why we are focusing on shorter time scale firming where we believe energy storage can do the most good in the near term.

Q. Can you see a day when, as a result of the development of energy storage technologies, there will be no need for a back-up to solar energy? 

For small micro-grid in remote locations, I believe this day is at hand. However for the rest of us who are not willing to pay such a high price for our power, it is still decades away.

Q. Are you presently working on this problem?  

Our focus is on helping solar integrate with the rest of the grid as it starts supply a larger power of the power demand, we are still years away from working on 100% solar solutions.

Q. How extensively are Maxwell’s ultracapacitor-based energy storage system used with renewable technologies? (I have read about it being used with wind, solar & EV’s) 

Maxwell has made a name for itself providing highly reliable, and long life back up power.  Our 16V modules have become an industry standard for backup power for wind turbine pitch control.  If you have ever seen a video of what happens when a wind turbine loses pitch control in a wind storm, then you have an idea of just how critical reliable power is in that application.

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  • globi

    Don’t forget hydro already provides 15% of the world’s electricity needs and many of the hydro power plants are amortized and produce electricity very cheaply and flexibly as well. The world won’t get rid of those hydro power plants in the future.

    • UKGary

      A lot of hydro power as you say is flexible especially where there is water storage in the system so making a superb complement to intermittent power sources. – In some cases you can install extra hydro capacity and reduce capacity factor so upping the capacity of the system to balance solar and wind.

      • GlennM

        Hi Guys,
        Good discussion, but I think most people are thinking too small.
        It is ALWAYS midday with bright sunshine, somewhere in the world. All we need is a good superconducting global circuit and we can definitely go 100% solar. Look at how quickly we went from a fibre optic cable that can only go 5-6 km to a worldwide network.

        • Bob_Wallace

          It would be pretty expensive to circle the globe with enough transmission to carry solar electricity from the dark side to the light side.

          And we’d have to install a massive number of panels. Consider that a particular spot on the globe is going to get about six hours of usable sunlight. During its six hours it would have to collect enough power for the “18 hours of planet” that would be “taking”.

          What makes more sense is to use a mix of what is available in each area and do some sharing across areas. The wind, in good windy places, blows a lot more hours per day than the Sun shines. Rivers run most of the time. Tides ebb and flow and can produce power more than half the time. Geothermal is pretty much ‘always on’. Biomass and biogas can produce 24/365. We’re starting to make progress with harvesting wave power.

          Then, there’s the problem that some of our sources just don’t supply all the time. Solar is great but there are times when an area is covered with clouds in the middle of the day. There are times the wind isn’t blowing in a particular place. Tidal flow stops at crest and trough.

          Mix everything together and we get a more consistent supply of power. That reduces the amount of storage and backup generation we need.

          • GlennM

            Hi Bob,
            I agree with you. I am just tired of the people whom say What do you do at night ?.
            No power source runs 24/7/365, not coal, nuclear, oil or anything else. We need intelligent mixes as you say. however i do believe that eventually solar will be the cheapest, with no moving parts like wind, and no need to pay for fuel eventually we will have a majority of solar, plus storage/transport of electric power globally.

          • Bob_Wallace

            Solar might become cheaper than wind, that’s a hard call. Wind is now about 5 cents per kWh and heading lower. Solar, using China’s $1/watt installed price, is close. Just for fun let’s assume that solar gets to 3 cents and wind to 4 cents.

            What you run into is the cost of storing solar to cover all the non-sunny hours. You’d have to be able to store solar (or ship it in from somewhere else) for a penny in order to make it as cheap as wind direct from the turbine.

            We have no storage technology that gets anywhere close to a penny per kWh. Best is pump-up hydro at six cents.

            The cheapest way to power a grid is to use whatever is available at the moment and avoid storage as much as possible.

  • Matt

    It is not going to be a one type only system. Yes if you own a roof and don’t have shade issues; you will have PV in the next 20 years. Likely much sooner. But there will be wind, geothermal, hydro, etc…

  • Bob_Wallace

    “solar energy will be able to supply all of our power needs”

    Yes, but it probably never will. The Sun shines too few hours per day. The wind blows a lot more hours. Using direct from source will almost certainly be cheaper than storing for future use.

    Wind is on its way to 5 cents/kWh, including transmission. Let’s say solar goes really cheap and hits 3 cents/kWh. Is there much chance we could store electricity at less than 2 cents? Unless stored solar is cheaper than wind, direct from the turbine, then solar won’t supply it all.

    And Hurrah! for UCSD. The campus that just keeps kicking out good stuff.

    • Jouni Valkonen

      remember also that if sun does not shine during the night, there is no need to use electricity during the night (other than is necessary). In solar economy, consumers of electricity must adjust their electricity demand to the supply of solar.

      My near term prediction (about 20 years ahead) is that electric cars and vertical farms are biggest electricity consumers. And they both can fully adapt to the intermittent supply of solar power.

      There is very little industry that cannot shut down the production during the nights if the difference of the price of day and night electricity is large enough. Today factories are driven in three shifts because night time electricity is cheap.

      • Bob_Wallace

        The wind blows at night. Rivers run. Tides ebb and flow. The Earth continues to be really hot if one drills down deep. Biogas and biomass know no clock.

        Power when we want it is quite possible 24/365 with a renewable grid. It’s just an issue of selecting the best sources in the proper amounts for each place and completing with storage.

    • eject

      I actually think that solar will contribute a lot more then wind will. I do agree that wind is more rational from an efficiency point of view but solar can be harvested everywhere.

      I can’t imagine owning a home without solar. I also can’t imagine that India will build wind turbines for all its citizens and connect them to the grid. Same goes for a lot of African countries. They will be on there own and solar allows them to get energy access step by step. If you now compare the populations you will see that they will very soonish consume more energy (well actually they already do) then what is now considered the developed world.

      Solar will probably lift most of the weight. I think it is easily conceivable that prices will actually go more towards fractions of cents for countries with cheap labor and little regulations. There is no technical limitation to building plants that can produce 100GWp worth of PV panels a year or something in that area.

      • Jouni Valkonen

        Thanks for the pointing important thing out that used EV batteries make splendid storage systems for solar panels. And indeed, there is plenty of supply for second hand EV batteries in 2030’s onwards!

      • Bob_Wallace

        India already has lot of wind on line. And the third (I think) largest wind turbine manufacturer is located in India.

        Wind has a big head start on solar.

        Solar will likely dominate in places which have no grid and where running a grid would be expensive.

        We simply differ in our predictions of which will be more used, wind or solar. I suspect our grids will use about 2x as much wind as solar. The wind blows around the clock and storage, even if cheap, has a cost. If nothing else there is a loss of power moving into and out of storage.

        Fractions of cents is a pretty harsh estimate. There are material costs, frame and cover glass, which would be hard to eliminate.

        My current guesstimation is 40% wind, 20% solar, 20% assorted (tidal, hydro, bio-stuff) and 20% stored whatever is available (wind or solar). Those are just rough numbers, you understand….. ;o)

        • eject

          I think fractions of cents are possible. Material costs for glass and aluminium are actually mostly energy costs. So there will be some sort of a positive feedback loop.
          There might also be new breakthroughs in cell and panel technology.

          What you are suggesting is basically that I can buy wind power from a energy company cheaper than I can make my own which will always make a difference if you have some EV to charge per family.

          But there are so many variables no one really seems to talk about at the moment. How is electricity/energy going to be taxed in future? Will you be taxed for an area of energy producing capacity you own as soon as you go over some sort of free capacity? Will there be a difference if I use electricity to heat my home or charge my Tesla? (being a “communist” European I actually think there should be a difference). There has to be a replacement for the tax on fossil fuels else I can’t see how social democracy can survive and I am not willing to give that up.

          Interesting time are ahead.

        • UKGary

          Well said Bob, for micro-grids in the sun band solar is the obvious choice for regular supply of modest amounts of power.

          Why? Because a useful amount of generation will always occur every day so with a bit of self control and a modestly oversized array, only 1 to 2 days worth of energy storage are necessary to maintain service.

          By contrast, whilst wind can deliver power at any time of day or night, it is far from unknown in less windy areas to have several days in a row with minimal opportunity to generate power. This necessitates far higher battery backup capacity as it must keep the system working without power generation for possibly a week at a time.

          Where wind scores off grid is where activities which are not time critical need to be powered – water pumping, grinding grain and the like which with with appropriate storage of water / milled grain can wait a few days until the wind is blowing.

          • Bob_Wallace

            I think we really want to watch how Eos System batteries work when they get added to the ConEd grid in a few months.

            Eos claims that they can “purchase” off-peak electricity and “sell it back”, all costs and profits included, for about $0.10/kWh.

            That would mean their batteries are less than 50% as expensive as deep cycle “golf cart” batteries which are pretty much the cheap storage option for off the grid.

            If we could cut the cost of storage by a significant amount then the micro-grid world changes.

            Individual residences/stores will probably find solar the best option. Small villages/towns may find adding a small turbine makes sense for their location. If they’ve got good wind potential then that might decrease the amount of storage they need.

            Something else that is happening is that older “developed world” wind farms are starting to upgrade their wind farms.

            Since many early farms were built in some of the best wind locations there are lots of 15+ year old turbines installed. And they are shorter tower, less swept area turbines. It’s paying to pull those old, smaller rigs down and replace them with taller, longer blade units.

            The removed turbines are being reconditioned and sold on to places where capital is not as available and there’s lots of available space. This is bringing much cheaper wind to places which probably couldn’t afford a state of the art turbine.

            So at the “larger micro-grid” level, the town, installing a reconditioned turbine to supplement their solar could be an attractive option.

          • UKGary

            If installing reconditioned turbines in the developing world, it is very important to consider operational and maintenance costs and availability of parts / skills. Also it is necessary to be sure that the local wind resource is adequate for the turbine under consideration.

            In some cases, particularly where small turbines are needed e.g. below around 25 kW it may be possible to source locally made / assembled turbines where there are the local skills available to maintain without outside expertise.

          • Bob_Wallace

            Having spent a lot of time in some of the less developed parts of the world I have no doubt that locals will gain the skills and find the parts.

            There are plenty smart people everywhere.

        • MySchizoBuddy

          you are talking about the Suzlon Group which is #5 according to business wire

          • Bob_Wallace

            Wiki has them at third largest in market share for 2012. But that’s the Suzon Group which also includes Senvion of Germany.

            But no big thing. Point is India is a player.

  • jburt56

    Ultracapacitors should be used for regenerative braking applications, not batteries.

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