Intermittant Renewables + Energy Storage = Base Load Power

August 12, 2010 – Vol.15 No.21

INTERMITTENT RENEWABLES + ENERGY STORAGE = BASE LOAD POWER.
by Bruce Mulliken, Green Energy News

Power grid-scale mass storage of electricity from intermittent renewable energy, such as wind or solar energy, is in its infancy. But it’s vital that energy storage technologies be developed if these renewables are to compete with base load electricity supply that churns out power 24/7.

Intermittent renewables are not the only place where energy storage can be utilized: Unsold power from base load conventional generation plants, such as coal, generated at off-peak times can be stored to sell during peak periods.

Energy storage technologies to be employed for stationary applications are quite different than those used in mobile applications such as a car or cell phone. Mobile applications need storage devices that are energy packed, yet small and light weight. Stationary applications need storage technologies at very low cost – including in long term operation – and can supply power for many hours, perhaps even days at a time. Small size and light weight may be nice features for stationary storage systems, but neither is really necessary. An energy storage facility for a large wind farm might have to be the size of a big-box store, but does that matter if it stores electricity cheaply?

Here are some of the latest projects in energy storage:

--- At its Michigan Assembly Plant in Wayne, Michigan, Ford Motor Company, with partners utility company Detroit Edison, Xtreme Power and the state of Michigan, are building a 500-kilowatt solar system that includes a 750-kilowatt battery energy storage system. The energy storage system that Xtreme will supply will store enough energy to power 100 average Michigan homes for a year.

The energy storage system will capture solar generated electricity that is not utilized immediately by the plant, particularly capturing power during weekend hours when the plant is closed. The system will also be able to store electricity from the grid, buying power for storage at off-peak times when rates are lower.

Electricity from the solar energy system will be used in the production of Ford’s next generation Focus, as well as the upcoming Focus Electric Vehicle. Further, solar electricity will also be used to energize 10 electric vehicle charging stations used to recharge electric switcher trucks that transport parts between adjacent facilities. Ford will also demonstrate the possibility of giving vehicle batteries a second life by using them to store energy from the grid or renewables after their useful life as vehicle power sources is over.

--- Lawrence Berkeley National Laboratory, Berkeley Lab, has plans to develop a flow battery using hydrogen-bromine chemistry. (Zinc bromine flow batteries are commercially available.) The research lab has been granted $1.6 million in the Stimulus Package, officially known as the American Recovery and Reinvestment Act (ARRA), to develop this “novel storage device” for the electric grid.

Berkeley describes the technology nicely, “Flow batteries are different from conventional batteries in that the energy and power are separated. In this way, flow batteries are similar to fuel cells and are also analogous to a car, where the internal combustion engine provides the power and the fuel tank provides the energy. To get faster acceleration, or more power, one can simply increase the size of the engine, and to increase the range, one can increase the size of the tank."

In another way to put it, a flow battery has a reactor that provides the power and external tanks that store the chemical reactants which provide the energy, says the Berkeley research team.

At the end of this two-year project, Berkeley Lab hopes to have a proof-of-concept for a flow battery that will have a high efficiency of 80 percent and cost less than $100 per kilowatt-hour of energy.

--- International Battery, a U.S. manufacturer and developer of large-format lithium-ion rechargeable batteries, is providing a battery storage system for a 200-kilowatt solar array being built by Princeton Power Systems at that company’s corporate headquarters. Princeton makes power conversion products.

The battery energy storage with International’s lithium-ion batteries will be housed in a shipping container. The transportable battery pack can be expanded up to one megawatt-hour of electricity storage. The completed system will be fully operational in the fourth quarter of this year.

International Battery says the energy storage efficiency should be in the 85 - 90 percent range. The whole project is valued at $1.5 million.

--- Altair Nanotechnologies(Altairnano), a developer of lithium-ion batteries, has signed a memorandum of understanding with the Hawaii Natural Energy Institute of the University of Hawaii at Manoa and the Hawaii Electric Light Company to supply a one megawatt energy storage system for a wind energy integration demonstration project. The project is to smooth the output of an operating wind farm with a high-rate of charging and discharging of the energy storage system. The project is not intended for lengthy energy storage, but could be.

--- Xcel Energy has been operating a one-megawatt wind-to-battery energy storage system since October 2008 at an 11 MW wind farm South Dakota.

The utility company says, “Collectively, the 20 50-kilowatt battery modules are roughly the size of two semi trailers and weigh approximately 80 tons. They are able to store about 7.2 megawatt-hours of electricity, with a charge/discharge capacity of one megawatt. Fully charged, the battery could power 500 homes for more than 7 hours “ The system uses commercially available sodium-sulfur batteries from NGK Insulators. This is the first U.S. application of the battery as a direct wind energy storage device.

xcelenergystorage

Sodium-sulfur batteries from NGK Insulators at South Dakota wind farm.

The final results of the test project won’t be available for another year but, said Frank Novachek, Xcel Energy director of corporate planning says, “We have proved that this technology can perform the functions of storage that we were looking for to help us manage the variability of wind energy on our operating system”

Xcel is offering its results to date on a web page (listed below).

--- Beacon Power is building a 20 MW flywheel energy storage facility in Stephentown, New York. The $69 million facility is to provide frequency regulation on the grid – ironing out the lumps in the supply and demand of electricity consumption. (Wind and solar energy can supply lumpy power.) The facility is not a mass energy storage device that could store power for many hours or days. Still, even though the flywheels spinning at up to 16,000 RPM can supply power for only minutes, the technology is considered helpful in the continued development of renewables.

The company has two more similar 20 MW projects in stages of development. A $43 million Department of Energy loan guarantee was instrumental in building the Stephentown project.

Links:

Xtreme Power
http://www.xtremepowerinc.com

Altairnano
http://www.altairnano.com

Berkeley Lab
http://www.lbl.gov

International Battery
http://www.internationalbattery.com

Xcel Energy
http://www.xcelenergy.com

Sodium Sulfur Battery Energy Storage
http://www.xcelenergy.com/Minnesota/Company/
Environment/Renewable%20Development%20Fund/
RDFProjects/Pages/SodiumSulfurBatteryEnergyStorage.aspx (click Milestone #5)

Beacon Power
http://www.beaconpower.com