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Power tech to combat climate change

Posted: 07 Dec 2015     Print Version  Bookmark and Share

Keywords:climate change  lithium ion  grid  renewable energy  battery 

Let's take a closer look at the battery, the core of what will make sustainable energy work, as nations gather to arrive at a worldwide agreement at the United Nations' Conference of the Parties (COP21) where the Intergovernmental Panel on Climate Change (IPCC 2015) will pronounce the progress of greenhouse warming.

Today we have wind farms and solar-cell farms and the ability to sell excess energy to the grid, but storing grid-sized excess energy is still the most outstanding problem facing both renewable energy sources and the grid itself. Large-scale batteries are still mostly dependent on massive banks of the same type of batteries that power your cell phone—lithium ion (Li-Ion)—but other solutions specifically designed for grid-sized problems are here, albeit unproven. But regardless of the battery technology used, what really count are the behind-the-meter systems and the mini- and micro-grids using them.

Paris 2015

The reason that electric vehicles (EVs), electric augmented airplanes, behind-the-meter solutions and even mini-grids still mostly depend on lithium ion batteries is that Li-Ion batteries are proven. Yes, they have had problems—like catching on fire—and yes they have to be amassed in banks by the hundred, and yes they are not the ideal solution for large-scale problems, but they are here. They work. Most of their problems are behind them. And industry is ramping up to make them cheaper and cheaper to manufacture and buy.

Panasonic and Samsung are two of the most prolific suppliers of inexpensive Li- ion batteries, but they need to be repackaged for grid sized solutions in order to achieve the kind of volumes necessary to get their price down there. Tesla Motors, famous for its EVs, is also marketing a Li-ion PowerWall that it suggests mating to roof-mounted solar cells in a home so that it charges during the day and supplies power at night for the house and, of course, to recharge the EV in the garage. With enough PowerWalls and solar cells, Tesla suggests that a household could go net-zero—that is, store enough energy to last all day and all night (plus, of course, recharge two EVs in the garage).

Tesla's motive is probably to get an even lower price on its Li-ion batteries for its EVs—the more you buy at a time, the cheaper their price—but it is also a new business for them, and thus a new revenue stream. (Tesla has also filed two U.S. patents recently—8,803,470 and 8,803,471—that combine traditional Li-ion cells with lithium-air cells whose power-to-weight ratio rivals that of petrol).


Tesla's PowerWall works behind-the-meter to collect energy from your solar cells, or at night when grid prices are cheaper, then supplies it to your home or your electric vehicle (EV) when prices are higher. But their real reason is to maximise the number of lithium ion batteries they buy from their suppliers so as to get a better price per unit which will therefore made their electric vehicles (EVs) cheaper. (Source: Tesla)

Beyond lithium

Tesla's patent actually mentions metal-air batteries, because they can also be built with a dozen different metals, and in fact most of the next-generation batteries use some variation of the traditional electrode-electrolyte-electrode architecture started with lead-acid batteries (in all petrol-powered cars) and repeated with different materials over the years ad nauseam.

Aquion battery

The Aquion battery showing the internal features of its battery cell where four series-contacted cavities house sets of electrodes connected electrically in parallel (a). The finished battery stack contains eight of these cell units stacked vertically (b). (Source: Aquion)

Take GE's Duration battery, a molten-salt electrolyte battery—officially a sodium-metal halide battery—with a 20-year lifetime and the ability to be built a grid-sized dimensions. Unfortunately molten salt apparently didn't make the cut, since GE discontinued the project just this year, but fear not—other salt-based batteries are already being made.

Sumitomo, for instance, built a salt-based battery that is molten at 61°C, much lower than GE's, and is nonflammable and is supposedly fire- and explosion-proof. The company claims its cells can be packed tighter—requiring half the space of lithium-ion batteries.

But for my money, I'm betting on the Aqueous Hybrid Ion (AHI) battery from Aquion Energy, which instead of molten salt uses salt water. A Bill Gates company—plus Advanced Technology Ventures, Bright Capital, Constellation Technology Ventures, Foundation Capital, Kleiner Perkins Caufield & Byers, Prelude Ventures, Shell Technology Ventures, Total Energy Ventures and Yung's Enterprise—Aquion is already producing 200MWh worth of batteries per year for grid level applications, with 1GWh capacity on tap in its current location for when orders ramp up. For all the details check out their white paper.

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