5 Boundary-Pushing Ways to Generate Renewable Energy

We all may still be suckling at the fossil fuel teat, but renewable energy certainly has broken into the mainstream at least in concept. There's still a long, long road ahead of us to bring enough green power online to really supplant large amounts of the carbon-emitting fuels we've grown used to using, but at this point large commercial wind turbines and rooftop solar panels aren't seen as wild and alternative ways of doing things any longer. But that doesn't mean things have become staid, not by a long shot. Here are five projects creating green energy that are still pushing the boundaries:

Hywind Floating Wind Turbine Towed Into Location
Even if you put an offshore wind farm 10-15 miles out at sea it's likely that there will be some opposition to the project on visual grounds, or, in some locations, on potential disruptions to shipping or navigation. One way that is slowly being put into practice that can circumvent some of these concerns are floating wind turbines.

In fact TreeHugger recently gave the concept a Best of Green award, even though at the time there weren't any full scale floating wind turbines in operation. Well, that's no longer true.

Norway's Statoil Hydro is towing the world's first full-scale floating offshore wind turbine into location, the HyWind, ten kilometers south of Karmøy. Once there it will start undergoing testing later this year, with testing to continue for the next two years.

The HyWind is a 2.3 MW turbine built by Siemens, with a floating portion that extends 100m below the ocean's surface. This is anchored to the sea floor with cables that can be up to 700m long. Power is transmitted back to the shore via undersea cables.

One problem that needs to be overcome: Wind speeds may be higher offshore, but it's also more expensive to build them offshore. Building a floating one is even more expensive.

image: Green Ocean Energy Ltd.
Wave Power Device Attaches to Offshore Wind Turbine
There are probably more variations on wave power than any other renewable energy source. One which is definitely flying under the radar, is really an add on to offshore wind turbines than a stand alone power generator: Green Ocean Energy Ltd's Wave Treader.

These devices are designed to be mounted to the tower of an offshore wind turbine (not sure if it would work on a floating one though...) and generate power as the side arms float up and down, moving a central cylinder, pressurizing hydraulic fluid and driving a hydraulic motor. The electricity produced is sent back to shore through the same cable as the wind turbine.

Each Wave Treader is rated at 500kW (so a 2.3 MW rated turbine becomes 2.8 MW). The first commercial version is expected in 2011.

Cold-Tolerant Jatropha Strain Discovered
There are plenty of problems with commercial-scale Jatropha production, but a new discovery by California's SG Biofuels promises to bypass at least one of them and to open up new land for cultivation.

Biofuels Digest reports that among the strains of Jatropha collected as part of the company's Genetic Resource Center, it has identified varieties collected in Central America at altitudes ranging from 5,200-6,000 feet. Temperatures there in the coldest parts of the year average around 45°F during the day and drop below freezing at night.

That's a big deal for Jatropha as though the plant is tolerant of a wide variety of water and soil conditions, it is extremely sensitive to cold, making it unsuitable for cultivation in the mainland United States. SG Biofuels is currently working on a breeding program for these cold tolerant varieties.

The downside of this is that SG Biofuels is predicting yields in the range of 200-300 gallons of oil per acre from these strains, far below what jatropha can produce in optimal conditions elsewhere.

Solar Cells Painted Onto Steel
It's been nearly six months since I first heard of Corus Group's announcement that it had developed a procedure to essentially paint dye-sensitized solar cells onto steel at the time of manufacture. This is how it was described at the time:

The photovoltaic paint consists of a layer of dye and a layer of electrolytes. This would get applied to the steel as one of four coats of paint: an undercoat, a layer of dye-sensitized solar cells, a layer of electrolyte or titanium dioxide, and finally a protective coating. The whole process would take place as the steel sheets get passed through rollers as they are manufactured.

Initially the first thing that popped into my head was the durability of the surface, what if it gets scratched, is it possible to repair sections of a structure made with this steel or do whole areas just go dead? Then there's the issue of efficiency. Will the devices using this steel be positioned well enough, enough of the time, to make it worthwhile to generate power from their surfaces?

Lots of questions, but it remains an intriguing idea to me. It's speculated that production could begin within three years.

image: Dartmouth Wave Energy
On-Demand Ocean Hydropower
Compared to some other renewable energy sources, generating power from the waves and tides is a predictable thing, with less of the intermittency of wind power for example, or at least predictable intermittency. One company which is looking at creating even more predictability in generating power from the ocean is the UK's Dartmouth Wave Energy.

Their oddly-named Searaser attaches to the sea floor by a flexible tether, which allows the device to move up and down with the motion of the ocean. A double piston action allows the Searaser to pump water as it both rises and falls.

This water is pumped to shore to either drive a turbine at sea level, or (and this is the part about on-demand ocean hydropower) pumped to shore and up a hill where it can be stored. The water could then be released as needed to drive a hydroelectric turbine.

So far this is just at a prototype stage and has pumped water successfully up a 160 foot tall hill. Its developers expect a full-sized version to be able to pump water up a 650 foot hill. Each of the full-sized devices is expected to be rated at about 0.25 MW.

And that seems to me, beyond anything else, to be the main problem. Not that the technology doesn't do it what it's designed to do, but that to generate electricity, in any sort of quantity, dozens of these would have to be used.

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