Their Battery is Full of Air

Storing electrical energy is a huge problem. A lot of gear we use every day use some form of battery and despite a few false starts at fuel cells, that isn’t likely to change any time soon. However, batteries or other forms of storage are important in many alternate energy schemes. Solar cells don’t produce when it is dark. Windmills only produce when the wind blows. So you need a way to store excess energy to use for the periods when you aren’t creating electricity. [Kris De Decker] has an interesting proposal: store energy using compressed air.

Compressed air storage is not a new idea. On a large scale, there have been examples of air compressed in underground caverns and then released to run a turbine at a future date. However, the efficiency of this is poor — around 40 to 50 percent — mainly because the air heats up during compression and often needs to be prewarmed (using energy from another source) prior to decompression to prevent freezing. By comparison, batteries can be 70 to 90 percent efficient, although they have their own problems, too.

The idea explored in this paper is not to try to store a power plant’s worth of energy in a giant underground cavern, but rather use smaller compressed air setups like you would use batteries to store power at the point of consumption. The technology is called micro-CAES (an acronym for compressed air energy storage).

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Supercapacitor Uses No Carbon

Supercapacitors have found a myriad of uses due to their ability to rapidly charge and then deliver the power efficiently. Currently, production of supercapacitors requires materials made out of carbon which requires high temperatures and poses other manufacturing difficulties.

Researchers announced a new type of supercapacitor that uses no carbon and could have advantages over conventional technologies. The new research focuses on metal-organic frameworks, or MOFs. This material is extremely porous with a sponge-like structure. Since supercapacitors require large surface areas, that makes MOFs an interesting material for that application. However, MOFs are not very electrically conductive, which is a disadvantage.

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Semisolid Lithium Ion Batteries Promise Better Cars, Solar

Lithium-ion batteries make possible smaller and lighter electronics. Unfortunately, they are also costly to produce. In a conventional lithium-ion battery, many thin layers create the finished product much like filo dough in baklava. A startup company called 24M thinks they have the answer to making less expensive lithium-ion batteries: a semisolid electrode made by mixing powders and liquid to form an electrolyte goo.

Not only will the batteries be cheaper and faster to create, but the cost of the factory will be less. Currently, 24M has a pilot manufacturing line, but by 2020 they expect to scale to produce batteries that cost less than $100 per kilowatt hour (today’s costs are about $200 to $250 for conventional batteries). Under $100, the batteries become competitive with the cost of internal combustion engines, according to the article.

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Storing Energy in Liquid Form

Researchers in Singapore have created a new kind of redox flow battery with an energy density around ten times higher than conventional redox flow batteries. Never heard of a redox flow battery? These rechargeable batteries have more in common with fuel cells than conventional batteries. They use two circulating liquids separated by a membrane as an electrolyte. Each liquid has its own tank, and you can recharge it by pumping in fresh electrolyte. The redox in the name is short for reduction-oxidation and refers to the process that stores energy in the two liquids. You can learn more about flow batteries in the video from Harvard below.

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