Integral to this future are batteries that cost a lot less than today and can last longer. This is because unlike conventional energy, which can be generated through the day, solar and wind power are intermittent and the latter cannot meet peak energy demand in the evening without storage.
Alternatives to lithium-ion — the reigning battery technology used in phones, laptops, electric cars and smart grids — are being talked about. For instance, solid-state batteries, which do not have the flammable liquid electrolytes present in lithium-ion. But lithium-ion is expected to be the default technology in the near future, especially as its efficiency improves and prices decline. Batteries now cost, on average, $156 per kilowatt hour, nearly 90% less than in 2010, and are expected to cost $100/kWh in 2023, according to BNEF. And global battery-making capacity is expected to more than treble by 2023, with two-thirds of the capacity in China alone.
Besides batteries, there is another, widely used way to store solar and wind power. In pumped storage hydropower, water is pumped from one reservoir to another at a higher elevation, using solar or wind power when demand for electricity is low.
Then during periods of high demand, water is released from the upper reservoir to lower reservoir through turbines as in traditional hydel power. These “water batteries” account for 94% of global energy storage capacity and had an installed capacity of 160 GW in 2018 (including 4.8 GW in India), according to the International Hydropower Association. Another 78 GW could be added by 2030.
With these storage options, we are closer to fixing the problem of renewable energy being abundant when we do not need it and scarce when we do.