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Published on August 6th, 2012 | by John Farrell


Are the Batteries Ready? 100% Clean Energy Requires Progress on Storage

August 6th, 2012 by  

In the long run, there’s no avoiding energy storage for a 100% renewable energy society. The two major sources of renewable power are wind and sun, and they are either fickle or reliably not available at night.

The problem is that the simplest energy storage option for electricity is batteries, and this image from Wikipedia (hat tip to Robert Rapier) illustrates a significant technical barrier: our simplest option is also among the least energy dense material we have.

There are two likely paths to a 100% renewable energy future in these circumstances: mass distribution of low-density, low-cost storage, or higher density storage.

In some respects, we’re already moving along the first path. Widespread availability of battery-powered iPads and laptops has led to great strides in greater energy density of batteries and lower cost. The following chart (used in our Democratizing the Electricity System report) illustrates the changes in the past 15 years.

Electrified transportation is the next iteration, using batteries that are orders of magnitude larger (e.g. a Nissan Leaf battery with 23 kW-hour capacity has 300 times the storage capacity of a Macbook Pro laptop battery). These are 1st-generation commercial batteries, with enormous improvements in capacity and cost likely. Furthermore, with hundreds of millions of cars, the sheer storage capacity of the U.S. vehicle fleet will be tremendous (over 4 billion kilowatt-hours) as electric vehicles become the drive train standard. And a recent study has shown that the storage capacity of 2.1 million vehicles can enable an additional 10 gigawatts of wind power on the grid (in the Northwest).

The Germans, ever the clean energy integration leaders, with over 15% of their electricity sourced from wind and solar, have also looked at electricity to hydrogen storage (a look at the above chart suggests the energy density of hydrogen has some advantages).  While not as efficient as batteries (two-thirds of power is lost, compared to 10-20% round trip for batteries), the resulting hydrogen can be used in natural gas power plants to provide backup power or piped into the natural gas network for building heat.  It’s not only flexible but it also could be useful because wind power in particular can peak during periods of low electricity use (nighttime).

The good (or bad, depending on your perspective) news for the U.S. is that renewable energy is such a small fraction of total electricity generation that energy storage isn’t yet necessary in any significant quantity. Existing power plants have sufficient spare capacity to fill the gaps left by variable renewables. While this state of affairs doesn’t endear the U.S. power industry to environmentalists, it does mean there is time to see storage technology improve.

I’m optimistic.

This post originally appeared on ILSR’s Energy Self-Reliant States blog.

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About the Author

directs the Democratic Energy program at ILSR and he focuses on energy policy developments that best expand the benefits of local ownership and dispersed generation of renewable energy. His seminal paper, Democratizing the Electricity System, describes how to blast the roadblocks to distributed renewable energy generation, and how such small-scale renewable energy projects are the key to the biggest strides in renewable energy development.
Farrell also authored the landmark report Energy Self-Reliant States, which serves as the definitive energy atlas for the United States, detailing the state-by-state renewable electricity generation potential. Farrell regularly provides discussion and analysis of distributed renewable energy policy on his blog, Energy Self-Reliant States (energyselfreliantstates.org), and articles are regularly syndicated on Grist and Renewable Energy World.
John Farrell can also be found on Twitter @johnffarrell, or at jfarrell@ilsr.org.

  • 3xE – energy storage

    But there are aleady energy storage solutions build for private users:
    and for solar/wind industry:

    It is existing technology.

    • Yes, we’re looking for more progress in this arena — needs to be more cost competitive.

  • Matt

    It really is just a question of leveling the field. Assume for a minute we use the  Harvard study for cost, yea it leaves out climate change cost, but you got to start somewhere. So first remove all coal and oil loop out, hand out, give back, etc. Then add externals, current US cost $500m/year. Start tax at 10%, then raise each year for 20 years. 10%, 20%, 30%, 40%, ….., 100%, 110%, …210%. While it would never raise $1050m/year in US, because use of coal oil would drop, you would see a ton or wind/solar/storage be installed in that time frame.

    Remember that the $0.05kwh would be closer to $0.30 externals added in, and wind/solar even with storage beats that hands down.

    For a more detailed write up, look back to the carbon tax write up post. Yes have to add some cost to imported products from countries not using carbon based energy, but on well. 

    • Bob_Wallace

      Craig Severance calculated that wind stored as pump-up hydro would cost about $0.18/kWh.  And that was back when wind was more expensive than now.

      Aquion is going into production with sodium-ion grid storage batteries which they project will give us $0.06/kWh storage, $0.11/kWh stored wind.  They predict being able to bring the price of storage down to $0.015/kWh.

      If someone has the storage price for A123 you could cut that approximately in half.   A123 recently announced their new formulation doubles 100% DoD cycles from 1,000 to 2,000.  That spreads cost over twice as many use cycles.

  • I will also mention that while cheaper storage would be great it’s not actually necessary.  A rich country like Australia could make its electricity sector carbon neutral with little pain at current energy storage costs.  Alternatively, CO2 released into the atmosphere from burning natural gas could be removed and sequestered..

  • tibi stibi

    this is a very interesting post. battery information is at this moment the most important because i see it as the last hurdle.
    i hope to see an article which will show costs of the larger ev battery’s over time (like the above graph)  and which will go up to 2012 instead of ending at 2005.

    keep up the good work! 😀

  • Dimitar Mirchev

    Probably second hand EV batteries will be used for storages before they totally die. And then we will recycle!

  • Cheap storage would be very useful, but even without it a large proportion of electricity can come from renewable sources.  In South Australia we get over a third of our electricity from wind and solar without any storage.  South Australia exports electricity to the neighboring state of Victoria which is a huge electricity sink, but even if South Australia’s electricity exports from all souces including natural gas are removed from the figure, wind and solar still supply about 27% of our electricity.  And as solar is load following, as it expands we will be able to increase the amount of electricity we get from renewables further.

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