Hot news in cleantech: Storing energy in t-shirts

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A solution for EV battery problems; storing energy in t-shirts; mapping offshore wind; and radars for wind turbines.

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In a week that saw a hybrid EV join the ranks of the world’s top three best-selling automobiles comes more good news for the electric vehicle sector, with a Colorado start-up claiming to have solved a key battery problem that has been holding back a lot of clean energy technology – not least of all electric cars. Technology Review reports that the company, Boulder Ionics, is developing a type of electrolyte, made from ionic liquids (salts that are molten below 100°C), that can operate at high voltages and temperatures, isn’t flammable, and doesn’t evaporate – and would thus enable the production of high performance batteries.

By replacing conventional electrolytes with ionic liquids, the team has found that the energy storage capacity of ultracapacitors could be doubled, by allowing them to be charged to higher voltages. And this could make it possible to replace a starter battery in a car with a battery the size of a flashlight, says Jerry Martin, Boulder Ionics’ CEO and cofounder. TR reports that the electrolytes could also help boost the storage capacity of the sort of lithium-ion batteries used in electric vehicles and mobile phones (in theory, by up to 10 times). They could also help make rechargeable metal-air batteries practical, because the electrolyte in such a battery is exposed to the air, and ionic liquids do not evaporate.

Boulder Ionics has built and demonstrated the key pieces of equipment needed for its process and used them to make evaluation samples for battery manufacturers. It also recently raised $4.3 million in venture capital. Martin says his company’s process could actually make ionic liquids that are cheaper than conventional electrolytes per watt-hour of energy storage in the batteries they enable.

Cottoning on to new power solutions

Speaking of flexible energy storage devices, a University of South Carolina-led team has been developing a way to turn a regular old t-shirt into just that. Discovery News reported this week that the team of engineers claim they have have successfully transformed a $5 cotton t-shirt into a flexible, highly conductive component, which is capable of charging devices. The research, recently published in the journal Advanced Materials, explains how the team worked to make the cotton highly conductive using several “recipes.”

USC mechanical engineer Profssor Xiaodong Li, who led the development with postdoc Dr Lihong Bao, says they started the process by soaking the cotton in a sodium fluoride solution for an hour; they then dried it in a preheated oven for three hours, and heated it in a hotter furnace for an hour. At the end of all this, the cotton had changed into activated carbon – charred-looking material that could nonetheless still be folded. The engineers then coated it with a nano-layer of the conductive metal manganese oxide – and there you have it, a super capacitor (that is, an energy storage device that is able to respond more quickly than a battery to power needs).

Testing has shown that the converted t-shirt’s performance is on par with other carbon-based super capacitors: After 1,000 cycles it had 97.3 per cent retention. “This is a very simple low-cost process, and it’s green,” says Li. As well as using a renewable plant-based material, the research group estimates that using cotton directly from textile mills could be as much as 10 times cheaper than chemically processing coal or petroleum into activated carbon. Of course, the process would need to be scaled up to get to market, and Li says that for this next phase, he’s looking for a potential industry partner. He’s also reaching out to state government leaders about using this process to help revive local textile production.

Wind balloons catch the offshore drift

As the global wind energy industry looks more and more to offshore as the next clean power frontier, a team of researchers has combined expertise in meteorology and aeronautics to create a system ready to find potent wind resources in the open ocean. On land, “wind power meteorology” is practiced using just a few instruments appropriately located. Offshore, however, it’s a whole other – much more expensive and logistically difficult – matter (not unlike the development of the offshore farms themselves). CleanTechnica reports that Andriy Lyasota, a Russian aeronautical engineer currently pursuing a master’s degree in energy engineering at the University of Barcelona, has been developing a system that does away with deep-sea foundations and floating platforms, instead combining a wi-fi connection with a balloon shaped like a fish.

The prototype balloon is around three meters long and is designed to withstand winds of up to 150 km/h and reach a height of 150 meters. The equipment it carries weighs about 4 kilos and, using a GPS, would be used to determine wind strength and direction. The balloon would be tethered to a common floating buoy. The system is expected to substantially reduce prospecting costs and minimise environmental impact. So far, says CleanTechnica, data collection tests have been very promising. But Lyasota says the ultimate goal is to “ensure that it can last up to a year in extreme conditions.”

Bird watching

Another technology currently being developed to further the cause of wind energy is advanced radar and telemetry systems, which Yale e360 reports are being considered for use on wind farms to reduce the number of birds killed by spinning turbine blades located in critical migration pathways. Says the website: “The so-called avian radar systems, which have been deployed at wind farms in Texas and Europe, would be able to identify birds early enough to shut down the turbines, at least briefly, to prevent collisions. Advocates say the systems could prevent large-scale killings of many migratory songbird species, as well as the critically endangered California condor and the federally protected golden eagle.” Gary Andrews, CEO of De Tect, a manufacturer of such systems, says many wind energy companies “are coming around to the view that they have to do something.” The systems, however, are very pricey, at $500,000 per unit. And existing technologies apparently have some difficulty differentiating among bird species.

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