Solar and wind produce electricity only when it's sunny or windy, and they will only displace coal if a cost-effective way of storing their excess power is developed. Plug-in hybrids and electric vehicles, meanwhile, will replace internal combustion engines only if they can get suburban commuters to work and back on a single, quick charge. The upshot: For clean tech to take over the world, cheap, powerful energy storage solutions are essential. And they're coming. After decades of ignoring this field, researchers and venture capitalists are pouring in, and interesting news is pouring out. Without doubt, the next generation of batteries and other storage technologies will be a lot better than the current one. But which will end up winning is very much an open question.
So let's start by dividing the field into two categories: mobile and stationary.
It's easy to power something that just sits there. You plug it in and turn it on, without much regard for the size or weight of the energy source. But if the device you're powering moves around, like a cell phone, laptop, or car, it has to carry its energy along for the ride. Size and weight matter, and all else being equal, the best mobile energy storage technology is the one with the highest energy density (i.e., the ability to pack the most power into the smallest, lightest form). This concept explains the dominance of the internal combustion engine: Gasoline is an extraordinarily efficient way to store energy, with a vastly higher ratio of energy to mass than any existing battery. GM's famous EV-1 electric car needed 1,200 pounds of lead acid batteries just to travel 100 miles on a charge, while a 20-gallon tank of gas weighs only about 150 pounds and can take a 20-mile-per-gallon car 400 miles. But in the coming decade, gasoline's dominance will be challenged by several new energy storage devices.
These are among the most promising:
For intermittent power sources like solar and wind, the ability to store excess electricity and make it available as needed spells the difference between producing baseline power-the most desirable kind-and being just a secondary source that the grid turns to after it has all the coal- and gas-fired plants it needs. Until very recently, the only commercially available form of stationary storage was a roomful of "deep cycle" lead acid batteries that were far too costly and high maintenance to be a viable large-scale solution. But lately, several more efficient stationary storage technologies have been developed. One of the most promising is a new generation of large fuel cells (Read More). Below are some of the other new technologies: