The key to harnessing wind and solar power is developing affordable batteries to store power, say researchers at Pacific Northwest National Laboratory in Richland.
Without advanced batteries, electricity from wind and solar power must be used the moment it is produced, whether or not the electrical grid needs it.
Researchers at the Department of Energy national lab in Richland say in a report published online in the journal Chemical Reviews that electrochemical energy storage systems show promise as advanced battery systems.
But those systems will need to evolve -- in some cases considerably -- if they are going to compete financially with the costs of natural gas production, the researchers said.
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The report identifies four promising types of electrochemical energy storage, or EES, systems, but all need further development to make them economical, safe or reliable. While making the batteries economical is the key to their widespread use, the report says, they also need to be built to last, using materials that are safe and durable so the batteries can operate more than 15 years and require very little maintenance over their lifetime.
The most commonly used battery systems today work by converting electricity to kinetic, or potential, energy and then discharging that energy back to the power grid when it's needed. But these systems, such as flywheels and pumped hydro and compressed air systems, have limiting factors such as lack of portability.
Electrochemical energy storage systems, on the other hand, can efficiently store electricity in chemicals and then release it upon demand. The EES systems work similar to a traditional household battery, but at a much larger scale, and use a variety of materials, like carbon, aluminum and even salt.
Like lead-acid batteries in a flashlight, batteries that store wind and solar power take in the electricity as it is produced and convert it to chemical energy, which is stored in the form of a liquid or solution.
When the energy is needed from the battery, an electric charge starts the chemical conversion of the energy back into electrons, which then can move back into a power line on the electric grid.
"By improving EES technologies, industry could tap into a near endless supply of wind and solar power and drastically reduce the dependence on fossil fuels to meet growing demand for electricity," Z. Gary Yang, PNNL laboratory fellow and lead author of the paper, said in a statement.
Yang said with further research the cost of these battery technologies could be reduced, their performance improved and advances in materials, chemistries, design and system engineering could occur.