A greener grid needs cheaper, better batteries

The Pacific Northwest National Laboratory reviews the top battery contenders for chemically storing renewable energy.
Written by Melissa Mahony, Contributor

Storage is a major concern for renewable energy systems such as wind and solar. When the air isn’t moving or the sun isn’t shining, electricity isn’t flowing as much from these farms. And when the weather complies, the grid can only handle so much incoming power at once.

Water, flywheels and maybe even magnetic fields are among the potential options for storing cleaner power, but the Pacific Northwest National Laboratory (PNNL) is looking to chemicals. Earlier this week, it released what it calls the most comprehensive review of electrochemical energy storage to date. Published in Chemical Reviews, the authors assess four leading batteries to chemically store energy and give renewable power sources better footing to compete against hydrocarbons.

The current contenders? The vanadium redox flow battery, the sodium-beta alumina membrane battery, the lithium-ion battery, and the lead-carbon battery. But the batteries don't just need to work. They must be reliable, hardy and safe—and let's not forget cheap.

The International Business Times reports:

Batteries are thousands of times more expensive than the electricity they store. You may be able to buy a kilowatt-hour (kWh) of electricity for a dime, but a battery to store that much electricity will set you back $150 to $1,000. Once you include battery depreciation in the equation, the cost of electricity from a battery is always higher than the cost of electricity from a wall-socket. If you only need to store a few watt-hours of energy for a cell phone or laptop computer, convenience will usually outweigh battery cost. If you need five, ten or twenty thousand watt-hours of battery capacity so that you can use electricity from solar panels at night or drive a plug-in vehicle 40 to 80 miles, battery cost quickly becomes a major issue, if not an insurmountable obstacle.

Well, let's hope at least one of the batteries will eventually surmount the cost issue. Below quickly sums up PNNL's review.

Vanadium redox flow battery
The hope:
Storage for up to 12 hours; Could integrate wind and solar power in a residential neighborhood or at several large industrial sites.
The problem: Making the battery portable, affordable and available in different sizes.

Sodium-beta alumina membrane battery
The hope: Could store a lot of energy in a small space; Its high energy density and rapid rate of charge and discharge would be good for powering electric cars and for other applications that require short, potent bursts of energy.
The problem: The high operating temperatures of the battery lead to safety concerns. Changing the shape of the battery, however, can improve efficiency, which might lower the safety risk and cost.

Lithium-ion battery
The hope: Making Li-ion batteries cheaper and safer would allow them to grow in size, with implications for the mass adoption of electric cars. The vehicles, in return, could serve as back-up storage for the grid.
The problem: This relatively old standby is expensive and prone to overheating and electrical shorting. A longer lifespan for the battery would also be a plus.

Lead-carbon battery
The hope: Could serve as a viable back-up source for wind and solar power because of their concentrated power. Gradual crystallization and buildup of lead sulfate within a lead-acid battery's core can cause the battery to lose its charge, and the corrosive acid also can eat away at a battery's core. Adding carbon to the battery seems to diminish this.
The problem: Research is still in its early stages. Capital costs are currently prohibitive.

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