A roundup of green headlines that caught our eye this week:

• A relatively clean-burning diesel Volkswagen Jetta TDI sedan won "Green Car of the Year" honors at the Los Angeles auto show, the first diesel-powered car to win the auto industry's highest environmental honor, Reuters reports.
• Retail king Wal-Mart will purchase electricity from a Duke Energy windpower project in Texas to light up 15 percent of its 360 stores in the Longhorn State, Wal-Mart's first direct purchase of windpower, says Green Tech Media.
• The Stata Center building at the Massachusetts Institute of Technology captures runoff waste water from storms in a giant cistern and reuses it in toilets in the building, the New York Times Green Inc. blog reports from the Greenbuild conference in Boston.
• Air Canada flight attendant Marcelo da Luz last month set a Guinness World Record for distance travelled in a sun-powered car of 9,320 miles throughout Canada and Alaska. Now he's pointing his flying-saucer-looking vehicle south to Argentina to extend the record, Canada's Globe and Mail reports.

Are solar cells really as "clean" as they're cracked up to be? Like most things, it all depends on whether you wash them or not.

Petaluma-based OCS Energy, Inc. has just introduced a product it calls SolarWash, touted as "the first commercially available automated photovoltaic (PV) panel cleaning system."

OCS Energy warns that the build-up of dirt over several months can cut power production from a solar cell array by as much as 25 percent. Taking its marketing cues from Proctor and Gamble, the company notes that in addition to dirt, PV system operators must also worry about "dust, tree debris, moss, sap, bugs, bird droppings, water spots, mold, and more."

Using microprocessor-controlled spray nozzles, the SolarWash system promises to maximize solar efficiency while saving on labor costs. It even comes with a web-based interface, something your garden watering system should no doubt incorporate as well.

Farther down the road, another technological breakthrough promises to shed even more light on solar cells. Researchers at Rensselaer Polytechnic Institute say they have discovered a new antireflective coating that allows solar panels to absorb 96 percent of all light that falls on them. Typical untreated silicon cells today absorb only 67 percent of available light, wasting the rest.

By absorbing radiation from a wide variety of angles and broad spectrum of frequencies (infrared through ultraviolet), the nanocoating promises to dramatically increase the efficiency of electricity generation from PV installations.

Despite its preference for the color green, the U.S. Army isn't the first organization that usually comes to mind when you think of environmental sustainability. But with annual spending of at least $3 billion on energy, the army says it's getting serious about energy efficiency and more sustainable energy production.

In addition to appointing a Senior Energy Council to advise the Army on energy policy, programs and funding, the secretary of the Army recently announced several new projects, including:

• the purchase of 4,000 small Neighborhood Electric Vehicles to replace gasoline-powered vehicles traditionally used by maintenance and operations staff for use on its posts;
• a major geothermal project at Hawthorne Army Depot, Nev., capable of producing 30 megawatts of clean power;
• biomass fuel demonstrations at six Army posts;
• a pilot energy savings performance contract with the private sector to serve as a model for monitoring and reducing energy consumption;
• and perhaps most exciting, a plan to partner with the private sector to construct a 500 megawatt solar thermal plant at Fort Irwin, Calif., in the Mojave Desert, to provide renewable power on the grid and provide the Army post with added energy security against disruption of power supply.

The Army's planned solar power installation enjoys a unique advantage: the Army owns its site and can thus streamline the permit process. Many solar pioneers are reportedly facing long and costly permit delays for projects on parcels controlled by the U.S. Bureau of Land Management. Oakland-based BrightSource Energy has warned that if the review process isn't speeded up, delays could send "a chilling signal to large-scale solar developers and their investors."

Bakersfield, California, sometimes called "the city that oil built," yesterday celebrated its commitment to what may well become the 21st century's leading rival to fossil-fuel energy: solar power.

At a Bakersfield ceremony attended by California Gov. Arnold Schwarzenegger and PG&E Chairman, CEO and President Peter Darbee, Palo Alto-based Ausra, Inc. unveiled the first solar thermal energy plant built in California in nearly 20 years.

The 5-megawatt (MW) Kimberlina demonstration plant, with its thousand-foot long mirrors, uses the same core technology that Ausra plans to install a couple of years from now in a 177-MW plant east of San Luis Obispo that will serve tens of thousands of PG&E customers.

Ausra's Compact Linear Fresnel Reflector (CLFR) solar technology focuses heat from the sun's rays to create steam to power steam turbine generators, much like traditional power plants, but without use of fossil fuels or harmful emissions.

PG&E's Darbee called the opening of the Kimberlina plant "an important step on the path to commercialization of this new technology."

He also underscored the importance of making continued investments in clean energy projects, despite the nation's difficult economic straits, in order to fight the enormous challenge of climate change.

"I want to restate our commitment as PG&E . . . that we will not take our eye off the ball, that we will continue to pursue energy efficiency, we will continue to pursue demand management, we will continue to pursue renewables," Darbee said.

Commenting on the financial risks that could delay new investments in clean energy projects, Darbee added, "PG&E stands ready, as we were before, to take on the challenge of financing renewables, to work with people collaboratively to move renewable generation forward."

San Francisco-based GreenVolts, which is on track to become the first supplier of utility-scale solar power to PG&E, yesterday announced that it won a $250,000 competitive grant from the California Energy Commission's Public Interest Energy Research (PIER) Program for a proposal to develop low-cost installation methods for concentrating photovoltaic (CPV) power.

CPV power uses lenses or mirrors to focus solar energy on photovoltaic cells that convert the sun's radiation directly into electricity. The Energy Commission's PIER program supports research, development and demonstration projects aimed (among other objectives) at "developing renewable energy technologies, products, and services that provide electricity customers with more affordable electricity, improved reliability, and a selection of choices."

GreenVolts is currently developing a two-megawatt facility using that technology in Byron, south of Brentwood, under a 20-year power purchase agreement with Pacific Gas & Electric. The full project should be completed next year.

PG&E's leadership in customer solar, recognized today by an award at the Solar Power International conference and described in Katie Romans' accompanying post, reflects in part the remarkable leadership the state of California has shown in this sector. 

The California Public Utility Commission (CPUC) reported a few days ago that more solar panels were installed in the first nine months of 2008 under the auspices of the California Solar Initiative than in any previous full year.

PG&E and the state's other two investor-owned utilities together hosted new installations of grid-connected solar photovoltaic capacity totalling 111 megawatts in the first three quarters of this year, up 37 percent over the total for all of 2007.

The California Solar Inititiative is slated to provide more than $2 billion in utility-sponsored rebates for customer solar installations over 10 years.

Thanks in part to programs like this, California housed 69 percent of all grid-connected photovoltaic capacity in the United States last year, according to a recent report by the Interstate Renewable Energy Council. California's total worked out to 9.1 watts per person, compared to 7.8 watts per person in Nevada.

The CPUC's report notes that customer demand for solar installations appears to be accelerating, based on the record-breaking number of new applications received in the third quarter (more than 3,000). However, a story in GreenTechMedia reports that some customers are opting to wait until next year to install systems, in order to cash in on higher tax incentives. Even so, the strong growth trend is likely to continue.

Do you wonder if you are a good candidate for rooftop solar power? Do you have $100 million to spend on a utility-scale solar plant, but need the ideal location?

Economic turmoil aside, one of the recent silver green linings is the passage of tax incentives for renewable energy development. Clearly the solar industry has much to celebrate, including the flurry of exciting announcements issued today:

• Gonzales Winery in Monterey County will soon be home to the world's largest winery solar power energy system. Sized at one megawatt, the system will be installed by Constellation Wines U.S. and will meet 50 percent of the winery's total energy requirements.
• The San Francisco Chronicle's David Baker reports on a California-based solar company that's shaking up the solar industry. Solyndra exited stealth mode today with a radically different approach to solar (think tubes), $600 million in funding and $1.2 billion in customer contracts.
• New thin-film manufacturer Konarka opened a new manufacturing plant today in Massachusetts that will have a production capacity of one gigawatt per year. Click here for the New York Times' report on the effort that is repurposing equipment from an old Polaroid printing facility.

The long struggle to extend federal tax credits for the renewable energy industry resembled a season of The Perils of Pauline: By one count it took nine votes in Congress before the long-awaited investment and production credits finally passed last week as part of the $700 billion financial rescue package.

The solar industry won an eight-year extension of a 30 percent credit for residential and commercial solar power installations. One industry-sponsored study predicts that this credit will create more than 400,000 new jobs in the solar power industry.

The bill also extends production tax credits to the biomass, geothermal and marine (wave and tidal) energy industries for two years, and to the wind power industry for one year.

By spurring the development of renewable energy, the credits promise a win for the environment, a win for the increasingly depressed U. S. economy, a win for emerging industries, and a win for PG&E and other utilities that have contracted with renewable power companies to provide cleaner energy for their customers.

Since the start of 2007, PG&E has contracted for more than 2,600 megawatts of new renewable power. Many of those projects are still under development and count on tax credits as a condition of financing and development. Failure to renew the credits could have put them, and hundreds like them around the country, in jeopardy.

PG&E worked hard to help Congress understand the need to act, in partnership with organizations such as Alliance to Save Energy, Business Council for Sustainable Energy, Clean Energy Now, Edison Electric Institute, and Solar Energy Industry Association. PG&E chief executive Peter Darbee stressed the critical need for tax incentives in an address to the 2008 United Nations Investor Summit on Climate Risk and in a lead opinion column in the San Francisco Chronicle, among other places.

Extension of the tax credits removes the single biggest hurdle to the development of renewable power, but not the only one. As the California Public Utilities Commission (and many other parties) have noted, continuing challenges include the cost and delay in building transmission to serve new renewable power plants, developer inexperience, financing uncertainty, and site control and permitting.

Investments in clean technology startups hit a record $2.6 billion in the third quarter, a 37 percent jump from the third quarter last year and a 17 percent hike over the second quarter this year, according to a report out this morning from the Cleantech Group. Total investments so far this year -- $6.6 billion -- are running ahead of $6 billion for all of 2007. California-based companies hauled in 42 percent of the investments.

Venture capital firms invested in 158 companies globally with a focus on three principal sectors -- smart power grids, algae companies, and solar power developers. Electric grid companies raised a record $202 million in the period, reflecting the growing move into plug-in electric vehicles by major automakers. Algae biofuel producers took in $95 million and solar power startups raised a record $620 million.

"Cleantech venture investing has continued to show strong growth despite the unprecedented turmoil in the credit markets during the quarter," said Michael Goguen, managing partner of Sequoia Capital and co-chair of Cleantech's advisory board. Cleantech is an investor group and market researcher.

Brian Fan, senior director of research for the Cleantech Group, said the third quarter "will probably be the high point for investment for at least several quarters," citing the current financial and economic troubles.

The five most active investors in the third quarter in the number of deals all have connections to Silicon Valley. RockPort Capital Partners topped the list with six deals, followed by Google Inc. with five, Advanced Technology Ventures and Kleiner Perkins Caufield & Byers with four each, and Khosla Ventures with three.

Both Kleiner Perkins and Khosla Ventures have invested in Ausra Inc., a solar-thermal energy systems company which is developing a solar plant for PG&E in central California. Ausra announced today that it has secured $60.6 million in its latest preferred equity financing from a group led by KERN Partners of Calgary, Alberta.