E•BOOM CAPITAL: Private Companies Pursue Renewable Energy Storage Challenge

SolarReserve’s (United Technologies) solar power and molten salt storage system

It is pretty clear that the economic viability of wind and solar energy and the extent to which they will contribute significant power to the grid depends on being able to generate electricity intermittently -- when the sun shines and the wind blows -- and store it for use when it needed and/or when the sun is not shining nor the wind blowing.

On Tuesday of this week, the first solar power plant in the U.S. capable of storing its own energy received a $1.45 billion loan guarantee from the U.S. Department of Energy. Abengoa Solar’s $2 billion 250 megawatt (MW) Solana concentrating solar project near Gila, Arizona, will include six hours of molten salt thermal energy storage capability, which will allow energy to be dispatched as needed during cloudy periods and after sunset. With this capability, Solana will be able to generate electricity well into the evening to help meet the summer peak demand for air conditioning. 

Likewise, electricity will never power vehicles in any meaningful numbers unless it can be stored in compact, rechargable, high-energy, long-life and low-cost batteries.

Private venture capital-supported companies are at the forefront of efforts to meet the renewable energy storage challenges. Here are five with very different approaches. 

SolarReserve, based in Santa Monica, California, was formed in 2007 by United Technologies Corporation’s (NYSE: UTX) subsidiary Rocketdyne and U.S. private equity firm U.S. Renewables Groups to use UTC’s proprietary technology to develop renewable power generation plants with energy storage capabilities. 

Unlike conventional solar energy projects which produce power only when the sun is shining and the wind is blowing, SolarReserve's power plants generate solar power, then store the energy in molten salt for delivery whenever it is needed, either 24 hours per day or only during "peak" demand. 

On Monday of this week, U.S. Secretary of Interior Ken Salazar greenlighted SolarReserve’s 110 megawatt (MW) Crescent Dunes Solar Energy Project in Nye County, Nevada. On Wednesday, SolarReserve announced a 25-year power purchase agreement for Crescent Dunes power with utility company NV Energy of Las Vegas. 

On December 15, SolarReserve’s 150 MW Crossroads Arizona solar energy project received state environmental permits. In November, the California Energy Commission permitted SolarReserve’s 150 MW Rice Solar Energy Project near Blythe, California. 

Overall, SolarReserve has a development portfolio of more than 25 projects featuring its solar power/storage technology with potential output of more than 3,000 megawatts in the United States and Europe, plus early-stage activities in Latin America, Africa, the Middle East, and Australia.

In addition to Rocketdyne and U.S. Renewable, SolarReserve’s venture supporters are Good Energies, Citigroup, Pacific Corporate Group, Credit Suisse, Nazarian Enterprises, CalPERS Clean Energy and Technology Fund, and Argonaut Private Equity.

Premium Power Corporation, founded in 2002 and based in North Reading, Massachusetts, claims to manufacture grid scalable zinc-bromide flow batteries that have the world's lowest cost -- with upfront costs lower than lead acid batteries and roughly equivalent to pumped hydro, at under 2 cents/kWh, on a long-term basis.

Low costs are made possible by using commonly available materials such as zinc, bromide salt, natural color high-density polyethylene plastic, and galvanized steel. Manufactured with commonly available materials, the systems are 100 percent disposable or recyclable, contain no toxic metals, emit no hydrogen gas, and require no fuel to operate.

Premium Power’s systems address a wide range of market applications, from small residential-scale systems to massive utility-scale systems comprising hundreds of megawatts of power and gigawatt-hours of energy. Customers include include wind and solar energy projects, off-grid backup for telecommunications facilities and for datacenters and computer rooms, and on-grid peak power load supplementation.

Venture support: Vantage Point Venture Partners

EnStorage, Inc., based in Zichron Yaacov, Israel, was founded to develop and commercialize energy storage systems based on regenerative fuel cells. 

During off-peak hours, power generated by solar or wind projects or excess power from the grid is used to convert chemicals from one form to another by electrolysis. Then, during peak-hours when the power is needed by the grid, these chemicals are fed into the fuel cell to produce power that is fed back into grid. This power production stage also converts the chemicals back to their original form and ready to repeat the cycle. 

The amount of power stored and regenerated is a function of the surface area of the cells in the fuel cell stack and the size of the chemical storage tanks. Both can be increased at little additional cost by increasing their size. The storage chemicals in Enstorage’s system are optimized to provide high efficiency at low cost. The efficiency required of the electrical-energy conversion is very high, approximately 75 percent. The same fuel cell stack is used both as an electrolyzer and as a fuel cell.

Venture support: Warburg Pincus, Greylock Partners, Canaan Partners, Wellington partners  and by Siemens Technology-to-business (TTB) fund.

Leyden Energy, formerly known as Mobius Power, Inc., was founded in 2007 under the uniform cell heat distribution technology patent acquired from chemical manufacturer Dupont. Leyden is one of many companies working to build better rechargeable lithium-batteries.

The company, based in Freemont, California, has developed lithium-ion batteries with thermal properties which allow operation at temperatures much higher than typical lithium-ion batteries. 

Leyden products use a conductive graphitic foil to increase reliability and also offer thermal conductivity that is beyond the capacity of conventional aluminum cathodes.

Leyden is targeting mobile devices, electric vehicles and grid storage systems. Leyden batteries are used to power electric motorcycles manufactured by Brammo, Inc. of Ashland, Oregon, to speeds of 100 mph and a range of 100 miles. On November 19, 2010, Leyden announced a technology partnership with Green Vehicles of Salinas, California, a manufacturer of electric vehicles that are capable of freeway speeds of 80 mph and a range of 100 miles.  

Venture support: LightSpeed Venture Partners, Walden International and Sigma Partners. 

Another lithium battery developer, Seeo Inc., based in Berkeley, California, was founded in 2007 on a technology license from Lawrence Berkeley National Laboratory. The company is targeting several markets, including electric vehicles and large-scale renewable energy storage.

Seeo says today’s lithium ion batteries are based on an intrinsically unstable materials platform. Chemical degradation leads to premature failure in existing applications resulting in catastrophic failures and explosions that are taking their toll on the industry and consumers alike.

The Seeo battery boasts a critical difference from current technologies: it is entirely solid state, with no flammable or volatile components. At the core of Seeo technology is a novel solid polymer electrolyte material that can transport lithium ions while providing inherently safe and stable support for very high energy electrode chemistries. As a result, Seeo claims dramatic improvements in energy density while also providing best-in-class product lifetime and safety. 

Venture support: Khosla Ventures, google.org, GSR Ventures, and Presidio Ventures (Sumitomo Corporation).

Photo credit: Solar Reserve

DISCLOSURE: The writer has no positions in, or professional connections with, these companies.