Hot news in cleantech: Ski lift power storage; 3D PV; and wind blimps | RenewEconomy

Hot news in cleantech: Ski lift power storage; 3D PV; and wind blimps

Using ski lifts to store solar energy, MIT’s amazing 3D solar panels, and the latest in wind energy – the blimp.


Last week, Bill Gates did a bit of talking about the world’s need for energy miracles and “crazy energy entrepreneurs,” and about various cleantech ideas and companies that had caught his entrepreneurial attention. This week, the team at Giga Om‘s Earth2Tech followed up on one of the latter: an energy storage start-up that Gates recently invested in, that was developing what he described as “gravel on ski lifts.” The team at Earth2Tech soon guessed that he was talking about the California-based Energy Cache (one of the Idealab group of companies), whose current mission includes creating a solar-powered pump for delivering materials to the top of mountains that can then be released to produce energy – aka “ski lift storage.” It’s “one of those topics discussed in the hallways of energy storage conferences for years,” says Earth2Tech’s Michael Kannellos. “It’s part of a segment I call macro or terrestrial storage, i.e. large mechanical devices that store power through the power of geography and gravity.” An interesting idea, he says, but one with many caveats.

Earth2Tech has since spoken to the founder and President of Energy Cache, Aaron Fyke, and got some interesting details on how its “ski lift” technology works, where the company’s headed and how Bill Gates and Idealab founder and cleantech guru Bill Gross became involved. Katie Fehrenbacher, who interviewed Fyke, says that his idea, which he worked on with help from Gross, was to model an energy storage technology on pumped hydro, but to use a motor and a cheap solid material instead of a liquid so that the system could be built in more locations and could also react more quickly. The result, she says, “is the hyper simple system that is Energy Cache’s intellectual property and the first of its kind” in the world: a system of buckets on a line that picks up gravel at the bottom of a hill, moves it to the top of the hill, and when the process is reversed, the gravel moves back down the hill and powers a generator to produce energy.

Fyke tells Earth2Tech that Energy Cache has built a 50kW prototype of its gravel bucket system in Irwindale, California – an effort that was funded by Clarement Creek Ventures (managing director Nat Goldhaber describes it as the most “out there” investment he has backed), Idealab and good old Bill Gates. The next step is to build a larger scale demonstration project that will roughly be the size of one commercial line, and between 500kW and 1MW. The company will then be looking to raise funds for its first commercial project, perhaps in as little as three years. And if the system works as planned, Goldhaber says, this could be “a very big deal.” Fyke says the company is already in discussions with grid operators in deregulated markets like ERCOT in Texas and California ISO in California.

MIT’s 3D solar tower power

A team of MIT researchers has come up with a very different approach to solar PV. Instead of arranging solar cells in flat panel formation, they have built cubes or towers that extend the solar cells upward in three-dimensional configurations. And the structures they’ve tested show some pretty amazing results: power output ranging from double to more than 20 times that of fixed flat panels with the same base area. MIT News reports that the findings – based on computer modeling as well as outdoor testing of real modules, and published in the journal Energy and Environmental Science – showed the biggest boosts in power in situations where improvements are most needed: locations far from the equator, in winter months and on cloudier days. “I think this concept could become an important part of the future of photovoltaics,” says the paper’s senior author, Jeffrey Grossman, the Carl Richard Soderberg Career Development Associate Professor of Power Engineering at MIT.

And while the cost of energy generated by MITs 3D modules exceeds that of ordinary flat panels, the expense is balanced by a much higher and more uniform power output; making it more predictable, which could, in turn, make integration with the power grid easier than with conventional systems. In fact, Grossman believes the time is ripe for such an innovation, because solar cells have become less expensive than accompanying support structures, wiring and installation. “Even 10 years ago, this idea wouldn’t have been economically justified because the modules cost so much,” he says. But now “the cost for silicon cells is a fraction of the total cost, a trend that will continue downward in the near future.” Currently, up to 65 per cent of the cost of PV energy is associated with installation, permission for use of land and other components besides the cells themselves, says MIT News.

The team analysed both simpler cubic and more complex accordion-like shapes in their rooftop experimental tests. For an accordion-like tower, the idea was to simulate a module that “you could ship flat, and then could unfold at the site,” says Grossman – such as could be installed in a parking lot to provide a charging station for electric vehicles. The team’s next step will be to study a collection of such towers, accounting for the shadows they might cast on eachother. The theory is that 3D shaped PV could have a big advantage anywhere where space is limited, such as urban environments, and could also be used in larger-scale applications, like solar farms, once shading effects are minimised. The challenge – as it often is with new technologies like this – is to mass produce these 3D solar structures in a cost-effective way.

High hopes for wind power

What do you get when you cross wind turbine with a blimp? Well, wind power start-up Altaeros Energies is hoping you get a viable clean energy option suitable for remote villages and military sites. You can see the unlikely looking airborne structure via the company’s spartan website, here – a prototype which the company this week said it had successfully tested, which is a traditional small wind (in this case, made by Southwest Skystream) turbine enclosed in an inflatable, helium-filled shell. CNet News reports that the Boston-based company is seeking to partner with others to build and test a commercial-scale version. As CNet’s Martin LaMonica points out, Altaeros Energy is one of a few companies developing systems to capture the stronger and steadier winds found at high altitudes. Others include Makani Power, Joby Energy, and Windlift.

For Altaeros’ test in Maine, its prototype machine was tethered by a cable (which transmits the electricity) and lifted to 350 feet (although it is designed to capture wind over 1,000 feet). At that height, the company says the Skystream turbine produced more than twice the power than a typical tower-mounted one. The prototype test also automatically hoisted and lowered the airborne turbine, which was attached to a towable trailer, says LaMonica. “Modern inflatable materials can lift wind turbines into more powerful winds almost everywhere – with a platform that is cost competitive and easy to setup from a shipping container,” said Altaeros CEO Ben Glass in a statement. The company is going after a very specific market, that could include military bases or remote off-grid industrial sites or villages. Longer term, it hopes to deploy its inflatable turbines offshore. LaMonica adds that the turbine’s shell was made by a sail-making company; the launcher converted from industrial blimps called aerostats used for heavy communications and radar equipment.

And in other news…

Watch NRG Energy CEO David Crane talk about the three green technologies he believes could cause disruptive change in the energy industry, at this week’s Cleantech Forum in San Francisco.

Read about (and see) how the Frank Lloyd Wright Foundation and First Solar, in conjunction with US energy efficiency consultant Big Green Zero, installed a 250kW solar photovoltaic array (that’s 4,000) solar panels’ worth) at the legendary architects’s Taliesin West campus, bringing it to net zero status, without marring the rooftops of the historic buildings.

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