In the city that never sleeps, the lights burn all night. But don’t worry, they’re not consuming precious fuel or polluting the environment, because the lights are running on giant batteries.

Liquid batteries. Batteries that are powered up in daylight from solar farms and excess grid capacity in off-peak periods.

It’s like having the whole city on an Uninterruptible Power Supply. The liquid batteries are huge tanks containing metallic ions and salts, capable of storing 15,000 megawatts of power. Enough to keep the town buzzing and the lights on – all night long.

The innovative battery design makes it cheap and relatively simple to store massive amounts of power, without losing out to the inefficiencies found in conventional batteries or pumped storage systems.

First discovered in 2009 by a chemistry professor at MIT, the batteries have been developed to the point where they can supply a whole city’s needs.

The big economic gain comes from using the batteries to smooth out the peaks in a normal demand cycle, reducing total New York power costs by a third! And renewable energy like solar power really comes into its own when you can store it.

The whole generation system is more flexible and robust – a full night’s power on standby means the power stations can be optimally run and maintained.

Key to the effectiveness of these batteries is their ability to be fully recharged every day, and drained at night, without degrading. The liquid electrodes dissolve in the salty electrolyte, and reform back into liquid alloys when the batteries are charged, with virtually no loss of material.

With a simple cycle of ‘electrons in – electrons out’ the batteries can keep on going indefinitely with only minor maintenance. Now everyone can use solar and wind energy – even when the sun isn’t shining and the wind won’t blow.

ANALYSIS >> SYNTHESIS: How this scenario came to be

Storing the grid
Donald Sadow­ay, a materials chemistry professor at MIT and one of the liquid battery’s inventors says: “No one had been able to get their arms around the problem of energy storage on a massive scale for the power grid. We’re literally looking at a battery capable of storing the grid.”

“Sadoway envisions wiring together large cells to form enormous battery packs. One big enough to meet the peak electricity demand in New York City–about 13,000 megawatts–would fill nearly 60,000 square meters. Charging it would require solar farms of unprecedented size, generating not only enough electricity to meet daytime power needs but enough excess power to charge the batteries for nighttime demand. The first systems will probably store energy produced during periods of low electricity demand for use during peak demand, thus reducing the need for new power plants and transmission lines.”

– from Technology Review