CLEANTECH BUZZ: Inflatable renewables

For those who fancy their wind turbines blown up, Energy Matters reports that an Israeli company is developing inflatable wind turbines using a design it says is feasible from 100 kilowatt units to multi-megawatt capacity models. The company, Winflex, has made the turbine's rotor out of an inflated wheel, from which blades connect to a central hub, and catch the wind in a similar way to a sail. Winflex says the rotor is lighter and safer than any other product currently on the market. And because its construction doesn't need expensive molds or specialised tooling, it is quicker and cheaper to assemble – Winflex says its product can reduce turbine installation costs by at least 50 per cent. The company has already designed, built, tested and successfully connected a 10kW and 200kW blow-up turbine to the grid for over two years and now plans to build a 1MW version. And there are plans for the commercial development of a 130kW unit which, with the supprt of the Israeli Ministry of Infrastructure, is at an advanced stage of design. Winflex also plans to licence the technology to other companies for mass production.

Solar tubes

And that's not all. As Energy Matters also reported last week, wind is not the only inflatable renewable technology about, with Austrian outfit Heliovis producing its patented HELIOtube – an inflatable solar concentrator made of plastic flim that concentrates light from the sun. As EM explains, light travels through the HELIOtube's transparent skin and then reflects off the downward curved mirror film, concentrating the sunlight in the upper chamber on a thermal absorber receiver. This focuses the solar radiation by a factor of up to 50. The sunlight is then converted into heat used to create steam, which can be piped to a turbine to generate electricity. If desired, high performance solar cells could replace the thermal absorbers to convert concentrated light directly into electricity, says the website.
  
The other main pros of the HELIOtube are the light weight and lower cost of the materials, with the one square meter of mirror surface weighing just 5kg, and the cost expected to be just over a quarter of the price of  standard parabolic troughs. Heliovis says the HELIOtube can be installed in solar thermal power stations or be used for photovoltaic applications involving concentration. The company is in the process of constructing a pilot plant in Dürnrohr, in Austria.

Problem solved? Maybe not

With its abundant reserves of fossil fuels, Canada – like Australia – has a particularly tough job ahead of it to forge a path to a low-carbon economy. Indeed, a new government study has predicted that the development of Canada's oil sands will single-handedly undo greenhouse gas gains made by weaning the country's electrical supply off coal. So, it's not entirely surprising to learn of a new and, supposedly, greener method of extracting oil from tar sands coming from the north American nation. The new technology, developed by Alberta-based N-Solv with $10 million in funding from the Canadian government, is reported to more than double the amount of oil that can be extracted oil sands while also reducing greenhouse-gas emissions from the process by up to 85 per cent.

How does it work? Well, Canada's oil sands, while plentiful enough to supply the US for decades, are made of a tar-like substance called bitumen, says Technology Review, which requires large amounts of energy to extract from the ground and prepare for transport. N-Solv's process requires less energy because it uses a solvent rather than steam to free the oil. A solvent like propane is heated to about 50 °C and injected into a bitumen deposit. This then breaks down the bitumen, allowing it to be pumped out along with the propane, which can be reused. This approach requires less energy than heating, pumping, and recycling water for steam, says TR. And the oil that results from the process requires less refining for it to be transported in a pipeline. And this process should be cheaper, too; both because it uses less energy and because, according to N-Solve's Murray Smith, the equipment would cost less.

The lab-tested process is now set to graduate to a pilot project that could produce 500 barrels of oil a day, says TR. And while that would be good news for Canada's oil export trade, David Keith from the University of Calgary points out that increased oil production may actually result in increased net greenhouse-gas emissions.