Things are looking sweet now for non-fossil fuels. Researchers at the University of Michigan have pioneered a method of manufacturing high-grade silicon for use in solar cells cheaply, using a concept familiar to making rock candy at home. UK researchers have also found a way of growing willow, used as feedstock for biomass and biofuel production, which increases its sugar yield – making the process more efficient and cheaper. Read more
“Rock candy” silicon could make ultra-cheap solar power
By Tina Casey in Cleantechnica (28 January 2013):
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 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.
This article was originally posted on Cleantechnica. Re-posted with permission.
Sugar-rich willow can boost biofuels’ green credentials
By Mark Kinver for BBC News (25 January 2013):
Willow is widely grown as a feedstock for biomass and biofuel industries
Scientists have identified willow trees that yield five times as much sugar as ordinary varieties, “drastically reducing” the impact of biofuels.
UK researchers found that if the trees grew at an angle, they produced a special kind of wood that resulted in the higher sugar content.
Willow, a short rotation coppice crop, is widely grown as a source for the biofuel and biomass industries.
The findings appear in the Biotechnology for Biofuels journal.
“It would drastically reduce [the environmental impact of biofuels] because you would not need such a severe pre-treatment in the conversion process, which is currently one of the highest energy consumption steps in the process of converting woody biomass to biofuels,” explained co-author Michael Ray, a researcher at Imperial College London.
Energy intensive pre-treatment processes are used to soften the wood before it goes through an enzymatic stage to break down the woody matter in order to produce biofuel.
“Our feeling is that these varieties that we know yield more sugar will need a much less severe pre-treatment process,” Dr Ray told BBC News.
“Ultimately, we will work towards producing varieties that actually will not need any pre-treatment at all and will be able to dissolve them in enzymes without undergoing any pre-treatment processes.”
He added that the findings could also improve the environmental performance of biofuels by increasing sugar yields, making the whole process more productive and cost effective.
“What we are really working towards here is sustainability, reducing the energy inputs and improving the energy and carbon balances, and reducing the competition for land that you could use for food production,” he said.
We hopefully will be able to… generate new varieties that will be easier to break down and use the sugars to produce biofuels”
Dr Ray and his colleague Dr Nicholas Brereton said the latest work built on previous work involving a wider study on willow varieties at the national collection at Rothamsted Research, which is the longest running agricultural research station in the world.
“We found in that study that certain varieties released more sugar than others, and in that same study we discovered that it had nothing to do with the total amount of sugars that were there, so we knew that it had to be something else that was causing the differences that we were seeing,” Dr Ray recalled.
“The phenomenon we are investigating is a natural phenomenon that is observed in most trees. You get a special type of wood (known as reaction wood) laid down in response to environmental stimuli, such as tipping or wind, which induces these special woods to be formed.”
“We found that the trees we tipped, compared with control trees that were not tipped, the different genotypes responded differently. Some of them did not release any additional sugar, even if you tipped them. Yet in others, there were very big differences.”
Reaction wood has a different cellular characteristic to normal wood and is formed when branches or stems have been disturbed and the tree attempts to return to its original position. It is also known as tension wood in deciduous trees and compression wood in conifers.
Working alongside colleagues from the University of Highlands and Islands, Scotland, the pair found the same results in the environment as well, allowing them to conclude that it was the effect of tipping that was triggering the response in the trees.
Dr Ray said that more research was needed in order to understand the underlying mechanism and identify what advantages the production of “reaction wood” offered to naturally growing tree.
“We just know that it is a natural response that we hopefully will be able to utilise that in order to generate new varieties that will be easier to break down and use the sugars to produce biofuels,” he observed.