Friday, January 25, 2013

New 'Rock Candy' Process To Manufacture Silicon Could Make Solar Power Even Cheaper

By Tina Casey Via Clean Technica

Researchers at the University of Michigan have come up with a low-cost way to manufacture high-grade silicon, based on a concept familiar to anyone who has tried to make rock candy at home. If the breakthrough can be translated into a commercially viable process, it would make ultra-cheap solar tech like V3Solar's Spin Cell (which we were just raving about the other day) even cheaper.

Ironically, funding for the research project came from the American Chemical Society Petroleum Research Fund, but maybe they know something we don't.

Cooking Up a Batch of Low-Cost Silicon

Silicon is the key component of conventional solar cells. It comes from silicon dioxide, aka sand, which is one of the cheapest and most abundant materials on Earth, but converting sand into high grade silicon is a high cost, energy intensive process with a pretty significant carbon footprint.

As described by U of Mich writer Kate McAlpine, the new process works at just 180 degrees Fahrenheit, which is a far cry from the 2,000 degrees needed for conventional silicon manufacturing.

The method basically consists of covering a liquid gallium electrode (gallium is a soft whitish metal that has a melting point around room temperature) with a layer of a solution based on silicon tetrachloride (a colorless, flammable liquid).

As in conventional silicon processing, electrons from the metal convert the silicon tetrachloride into raw silicon. The new twist is that by using soft metal with a low melting point, the research team was able to get the raw silicon to form crystals without exposing the solution to additional heat.

A Ways to Go for Low Cost Silicon

The team has observed films of silicon crystals forming on the liquid gallium electrodes, but so far the individual crystals are only about 1/2000th (yes that's 1/2000th) of a millimeter in diameter.

There is still a long way to go before the process jumps from the lab into commercial viability, and the next steps include experimenting with other metal alloys that have low melting points.

Meanwhile, other routes to low-cost silicon based solar power are at or near commercial development, and they could go even lower if the U Mich research pans out.

One approach, illustrated by the aforementioned V3Solar Spin Cell (which by the way began life as Solarphasec), is to squeeze more power out of conventional solar cells by reconfiguring the solar module.

The Spin Cell reboots the typical flat solar panel into a 3-D cone. Along similar lines, MIT researchers have come up with a solar "tower of power" that takes advantage of 3-D angles.

The 3-D concept can also be internalized, as demonstrated by a company called (what else) Solar3D.

On a completely different note, the Obama Administration is also focusing on lowering the "soft costs" of solar power, which typically account for half the cost of a completed solar installation.

The Petroleum Research Fund

Well, here's hoping. In any case, the really interesting part of the story is the involvement of the Petroleum Research Fund, which states at the top of its home page that its mission is to support "fundamental research directly related to petroleum or fossil fuels."

In its vision statement following that declaration, the Fund waxes a little more expansive, describing itself as dedicated to "significantly increasing the world's energy options," though directly after the following note appears: "Proposals will no longer be considered in solar power, which includes photovoltaics and solar cells."

Apparently the U Mich project got in under the wire, but it shouldn't be surprising that a grant-making organization with roots in the petroleum industry was at least once open to solar power research.

Solar power has long been used as an economical way to provide energy to remote oil fields, where grid connections would be difficult if not impossible.

Given the energy intensity of harvesting unconventional oil, most notably from Canada's tar sands, low-cost power in any form would be a welcome development for the petroleum industry.

- Tina Casey, reprinted from Clean Technica with permission



http://thinkprogress.org/climate/2013/01/25/1497561/new-rock-candy-pro


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