A few days ago, another article appeared in the SF Chronicle that discusses some of the more technical aspects of alternative energy production. I especially liked the graphic on the 37 foot wide "Dish concentrators" for generating solar energy out in the desert near Edwards Air Force Base. Also the discussion of the connection between lignin and cellulosic ethanol.
Here is the link. I reprinted the article in full below.
Also I noticed this article on "the best natural highlights in California" and thought it worth mentioning:
For the greatest of the truly great, stick to California
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Unlocking clean, cheap energy
California scientists look to ethanol, solar arrays and 1800s engine for answers
California scientists are playing key roles in developing new energy technologies to counteract the effects of global warming.
Nanotech solar cells, the world's largest planned solar-electricity plant and new technologies for breeding biofuels like ethanol are among the brighter prospects on the energy research front in the Bay Area and the Golden State.
The basic technologies already exist. The main problems the scientists say they face are not scientific but rather are figuring out technical ways to refine and cheapen the technologies until they're reliable and cost-competitive with other energy sources.
And getting there, some scientists admit, could take years of research.
In the East Bay, scientists at U.S. Energy Department laboratories are exploring ways to use enzymes, microbes and even termites to generate more commercially appealing forms of biofuel such as ethanol.
At present, ethanol for transportation is produced from the starch in corn. Unfortunately, the ethanol-making process is so energy-intensive that the resulting ethanol yields only slightly more energy than was required to make it.
So scientists are seeking technical ways to produce ethanol more efficiently. They're doing this by investigating how to extract energy from the non-starch parts of plants, especially woody plants that are rich in cellulose, which is rich in the carbon- and hydrogen-based molecules that are useful for clean fuel. The goal is to develop an economically attractive form of auto fuel called cellulosic ethanol.
It won't be easy. Visionaries especially hope to use gene-modifying tricks to degrade cellulose more efficiently -- say, by creating genetically modified plant feedstocks, such as poplar trees, that would decompose more readily. However, Chris Somerville, a prominent Bay Area plant scientist and biofuel entrepreneur, said the history of genetic engineering of organisms indicates it could take at least a decade to invent and license commercially appealing genetic techniques for biofuel production.
"The biggest technical obstacle," said Prof. Charles E. Wyman of the Center for Environmental Research and Technology at UC Riverside, "is to overcome the natural resistance of cellulosic biomass to break down (and) release sugars," from which ethanol can be manufactured.
"The challenge is that no one wants to take the risk of trying to commercialize the (cellulosic ethanol) technology for the first time as the process is capital-intensive," Wyman said. "Yet converting cellulosic biomass to fuels is virtually the only option we have for making sustainable liquid transportation fuels with virtually no greenhouse gas emissions that can make a major impact on oil imports."
Over millions of years of evolution, the tougher parts of plants have developed dense, intertwined layers of molecules that resist being broken down by natural forces -- a phenomenon called "biomass recalcitrance." One of the toughest cellulose components is a substance called lignin, which gives plants their stiffness and ability to stand upright. If scientists can figure out how to break down lignin, they could more easily tap into the plant's energy riches -- just as kids can get at the ice cream if they figure out how to break into an ice cream store.
Scientists at the U.S. Energy Department's Joint Genome Institute in Walnut Creek and the California Institute of Technology are seeking help from termites, nature's most proficient cellulose eater.
Termites contain hundreds of different types of enzymes that digest cellulose. If researchers can figure out which enzymes are the most efficient cellulose-destroyers, they might be able to extract them from termites and inject them into the ethanol-production process to break down cellulose.
Phil Hugenholtz, a microbial ecologist at the Walnut Creek lab, said some experts suspect the enzymes won't be nearly as effective outside of the termites' bodies, just as a carburetor is useless outside of a car.
"We'll find out in the next couple of years," he said.
Right now, ethanol research is getting the bulk of media coverage, but research persists on longer-established alternate energy technologies.
At Nanosolar Inc. in Palo Alto and at Los Alamos National Laboratory in New Mexico, scientists are figuring out ways to extract new energy from the sun by developing nanotech and ultra-lightweight solar-electric cells. Existing solar-electric technology relies mainly on cells made of silicon, but they've become the Model Ts of solar power, generating too little energy to be attractive for many of the more energy-intensive uses, such as powering entire cities.
The problem is figuring out how to beat more electricity out of solar-electric cells.
Normally, when a solar cell is hit by a particle of light known as a photon, the cell emits a single electron or negatively charged particle. However, scientists have found that when they fire a photon at an extremely tiny semiconductor called a nanocrystal (just a few millionths of a meter wide), it can emit far more energy -- up to seven electrons at once.
The effect, known as carrier multiplication, has stirred debate among physicists, who disagree on its cause. Some think it can be explained in terms of known physics, while others think new scientific theories will be needed to explain it.
"We have to make (solar) cells much more cheaply and with higher efficiencies than silicon cells," and nanotech cells offer one way to do that, said Victor Klimov, a physical chemist and team leader at the Los Alamos lab. He thinks nanocrystal solar cells made from lead, cadmium, selenium or other substances might eventually generate more than 40 percent more electricity than existing silicon solar cells.
But there's a catch: For now, the electrons can't escape from the nanocrystal that traps them, thus preventing the electricity from being funneled into a power grid. Some researchers are developing microscopic wires that, they hope, will solve the problem.
Meanwhile, Nanosolar is developing new "thin film" solar cells that are one-100th the thickness of ordinary cells, although they can generate about the same amount of electricity.
But there are challenges, said Martin Roscheisen, the company's chief executive officer.
"The amount of capital involved is quite high, (and) it's a matter of getting the details right, (of) getting (production up) to high yield fast," he said. He expects the company's first solar-electric panels to roll off the assembly line at its San Jose plant some time later this year.
Perhaps the most spectacular near-term development in solar power will be the opening of the world's biggest solar-electric plant sometime in 2009 on 4,500 acres of the Mojave Desert near Victorville in San Bernardino County. Approved for construction in 2005 by the California Energy Commission, the plant weds 19th century engine technology and solar power to today's electric grid.
An array of 20,000 37-foot-wide reflective dishes will reflect sunlight onto engines that contain hydrogen gas. The heat will make the gas expand, which, in turn, will drive a piston, crank shaft and drive shaft assembly connected to a generator that produces electricity. It's expected to generate at least 500 megawatts, enough to power 300,000 homes.
It's an example of how sometimes, the oldest is best, for the Stirling engine is an update of an engine technology as ancient as the Industrial Revolution.
"The Stirling engine was invented back in the early 1800s (by) a Scottish minister and inventor," said Bruce Osborn, chief executive officer of a Phoenix company, Stirling Energy Systems, which is building the plant for Southern California Edison. "It's a very simple, very elegant, very efficient system."
E-mail Keay Davidson at kdavidson@sfchronicle.com.
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