Investors are getting more bullish about the energy storage market, which is emerging to complement the increasing solar power generation and provide backup power for businesses that could lose millions of dollars in sales during a blackout.
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Take a look at California-based Primus Power, which on Tuesday said it’s raised $20 million in venture capital as part of a Series C round. The startup is working on raising another $15 million to complete the round, said CEO Tom Stepien. Overall, the company has raised $35 million in equity since its inception in 2009.
Batteries or other types of energy storage could store the intermittently produced solar and wind power and dispatch the stored energy into the grid only when demand is there. As the amount of solar and wind generation grows, utilities and grid operators anticipate a great need for energy storage technology to help them keep the grid humming by maintaining a balance of supply and demand.
Batteries also are attracting businesses that want backup power or use energy storage to help them reduce the amount they have to pay to their utilities for using electricity when demand is high and the electric rates are high.
Another reason energy storage technology is getting more attention these days is California’s new program that will require the three big utilities to collectively buy 1,325 megawatts of energy storage services by 2020. The first bidding process is scheduled to take place by the end of this year.
The Series C round will provide the fuel to launch Primus’s technology into the market. Primus has contracts to deliver its giant batteries to Puget Sound Energy in Washington State and the Marine Corps Air Station Miramar in San Diego this year.
The Marine Corps project involves a microgrid, which includes a collection of power generation and storage equipment that will continue to produce electricity for use within the microgrid while the greater electric grid is down due to power outages.
Primus develops what’s called flow battery, which is rechargeable and gets its name from its containers that house the energy-storing materials and electrolyte. A flow battery produces electricity when the liquid electrolyte flows through a cell and react with electrodes inside the cell. Energy storing materials that are most commonly chosen for developing flow batteries include iron, vanadium, zinc and bromine.
Flow battery proponents says the design makes it easy to size up and down the battery. If you want a more powerful battery, you would increase the size of the containers. But flow batteries are bulky and not so portable.
Primus engineers zinc bromine flow battery that is quite different than the traditional flow battery designs. It uses metal electrodes rather than plastic or felt, and while metal is more expensive, it also is more conductive and can produce more energy.
The company also forgoes the conventional two-tank designs for feeding the negative and positive electrolytes to the cell. Instead, there is one tank that has different outlets to separate the electrolyte piping the electrolyte to the cell at different rates.
Separating the electrolytes this way also makes it possible to ditch the membrane in the middle of the cell, an expensive component. Primus isn’t the only one developing a membrane-less stack. Other research also has been under way to eliminate the membrane.
Each Primus battery system contains 14 fridge-size cells, which collectively store 1,000 kilowatt-hour of energy. Puget Sound is set to get two systems while the Marine Corps. will get one.
Primus has won a $14 million grant from the U.S. Department of Energy for a $46.7 million project to install 25 megawatt, or 75 megawatt hours, of batteries at the Modesto Irrigation District in central California. The batteries would help the district to store wind power when demand is low and use it when demand for electricity is high.
Primus initially planned to build the Modesto project in 2013. But the district was having trouble coming with the funds necessary for the project, Stepien said. With electricity demand starts to increase, Modesto expects to have the money for the project shortly. Primus plans to ship the battery system to Modesto in 2015.
Primus is competing with a host of battery companies that all want a slice of this emerging storage market. Other flow battery makers include Imergy Power Systems, EnerVault and ZBB. Then there are lithium-ion battery makers that also are counting on winning projects with utilities and businesses.
Strong competition and a need to raise ample money to engineer, produce, sell and install batteries are challenges that have caused some battery makers to fall. Xtreme Power, for example, recently files for bankruptcy.