What is the difference between a battery and a power source? It is sometimes hard to distinguish. If you build a dam and capture the energy of falling water, it is considered power generation from a power source, namely gravity. But if you pump water up a hill and store it behind a dam until you need it, that's acting as a battery; it is not making energy, it is just storing it. It is a really important distinction; it is one of the reasons we are not fans of hydrogen, considering it more a battery than a fuel.
Diane Cardwell of The New York Times writes about The Biggest, Strangest "Batteries" and explains how really, anything that can store energy and release it later is a battery.
It’s usually (but not always) still too impractical to string together enough traditional batteries — those powered by chemical reactions, like the ones in smoke alarms and Teslas — to do the job. Instead, with remarkable ingenuity, technicians have relied on a host of physical forces and states such as temperature, friction, gravity and inertia to keep energy locked up for later release.
We have covered many of these batteries in TreeHugger, although not with the cute graphics that they have on the New York Times website. Here is a roundup; the photos are sometimes small because these stories are really old. It also should be noted that many of these ideas were proposed before Elon Musk and Tesla introduced their most recent big chemical batteries, which I suspect may curb our enthusiasm for many of these. They may just not make much sense anymore.
As we've said many times in the past, wind power is great, but to use it to its fullest potential, we need to figure out how to cheaply store the energy that it produces at times when we don't need it (meaning mostly at night). More in TreeHugger: Storing Wind Power Energy in Compressed Air Tanks Could Change the World
The most common complaint lodged against solar power is that -- say it with me now -- it's only able to provide power when it's light outside. Solar developers have tried to solve this problem a number of ways, and using molten salt to store the heat is one of the most promising. And the technology is now ready to move beyond the drawing board -- California just approved its first molten salt solar power plant. More in TreeHugger: First Molten Salt Power Plant Approved in California and Proposed 150 MW Solar Plant Would Store 7 Hours of Sun's Energy in Molten Salt
Here's a pretty cool example of energy harvesting: VYCON Energy's REGEN crane system, used at cargo ports, which captures some of the energy from lowering shipping containers using a flywheel, and makes a serious dent in reducing the amount of diesel fuel these massive cranes consume:The cranes normally run on diesel generators 500-800 kw in size. Not only do they provide power to lift the shipping containers themselves, but also need to run while lowering the container, to ensure that the box is controlled on the descent. That's where the REGEN system comes into play. More in TreeHugger: Flywheel Energy Harvesting System Puts Big Dent in Fuel Consumption at Cargo Ports
Pumped Hydro Storage
It's long been known that pumped-hydro storage could help wind and solar to take a greater share of the energy market. By pumping water uphill when the wind is blowing and the sun is shining, we can save it for later use when demand is up but production is down. More in TreeHugger: More Pumped Hydro Storage Could Help Wind & Solar Power andScottish Power aims for 400MW of pumped-hydro energy storage
Rocks, trains and a big hill
We love renewable energy, but it can be hard to store. That's why people are building better batteries, flywheels, big balloons in lakes and other expensive new technologies. And then there is Ares, an idea with real potential. It's basically a couple of shipping containers full of rocks. When your renewable sources like wind and solar are all pumping out more power than you can use, you use the excess to push the train full of rocks up a hill. When you need the power, you let the train roll down the hill, and the electric motors turn into generators. That's it. Rocks. More in TreeHugger: Rocks, rails and a big hill are all you need to store renewables.
Make nice with ice
By using thermal energy storage instead, ice is created during low-demand hours using low-cost, low-emission energy. The next day, during peak-demand hours, renewable energy can be used to meet the building's demand for cooling. Energy storage can kick on when the sun isn't shining, thus, reducing the peak demand, flattening the building's electrical profile, and improving the grid's load factor.
More in TreeHugger: Zero Energy Buildings should make nice with ice
But is it all for naught?
The Times article lists all these options, but somehow hauling rocks up a hill or compressing air into caverns doesn't make as much sense when you can now buy big batteries and just sit them on the ground anywhere. This used to be a fantasy, nobody believed it was possible or affordable. But Tesla and Musk did it. More in TreeHugger: Tesla kills the duck with big batteries.
It's a great article in the Times, but it is likely that most of those technologies have just been made obsolete.