One of the ongoing debates in the green building market is over the future of windows. Should building owners go with windows containing passive films that can keep heat in during the winter and the sun's heat out during the summer or should they go for fancier electrochromic windows that change their tint with the weather? Passive films are cheap and they don't require maintenance once installed. Companies like Denmark's Photosolar (see video here) say they can keep 50 percent of the sun's heat out by inserting a designer film between two sheets of glass. Serious Materials has a new line of windows that it says insulate better than most walls. (Shameless plug: Windows will be one of the several topics at our Green Building Summit in June.) But the problem? Tint, says John Van Dine, CEO of Sage Electrochromics, which makes electrochromic windows. Van Dine, naturally, is a little biased in the debate. He's been working on electrochromic windows since 1989 and the products are just now coming to market, but he makes some great points. Architects and builders put in windows because people want sunlight, he noted. Sunlight is a far higher quality light than comes out of light bulbs. (That's one of the many reasons you look better outdoors than under a florescent bulb in a hotel bathroom.) Passive windows remain in a perpetual shade of gray. Electrochromics go from clear to dark; electrochromics thus get points for quality-of-life. Putting sunlight into a building means running the air conditioner at higher levels. Heating and air conditioning account for about 16 percent of all energy consumed in the U.S. and most buildings are not heated and cooled efficiently, according to several experts. "We do a lot of things because glass is not energy efficient," he said. The energy balance on electrochromic windows is quite good, he says. Darkening a window (which is accomplished by electrically stimulating molecules in a film inside the window) takes only 0.28 watts per square foot of glass; maintaining the tint takes about a tenth of a watt. Controlling 1,500 square feet of glass takes about the same amount of energy as it takes to flip on a 60 watt bulb. You could run much of a building's window system on solar cells. In turn, building operators can turn down the air conditioner. It is also possible to turn down interior lights as the tint decreases. Orchestrating the symphony between sunlight, interior light and the tint of the windows isn't easy, Van Dine concedes, but several companies such as Tririga and Cimetrics are working on building management systems that will make this much easier in the future. And, of course, dynamic controls aren't really feasible with a passive window, he added. Passively tinted windows may also requiring wiring too: Photosolar, among others, wants to add transparent photovoltaic cells into their windows. Wiring? Doesn't this mean that electricians have to work with glaziers to run wires through windows? Yes, but they already are. Security systems that detect window break-ins are wired. The windows cost more than conventional windows right now, but the cost will decline. He admits it has taken a while to get to market. Although dating back to the late '80s, Sage only began very limited mass production in 2002. It recently raised another $20 million from its investors. Either way, we will likely see this debate played out over the next five years. The European Union, California and other jurisdictions have begun to pass more stringent building codes that will require better windows. It will be interesting to see what builders choose.

Aurora Biofuels, which wants to turn ponds of algae into diesel, has appointed Robert Walsh as CEO. Walsh was previously the president of LS9, which wants to use genetically engineered e coli to produce hydrocarbons. Before that he worked for years in the fuel business. Aurora is one of the 50 plus companies trying to turn pond scum into fuel. It was founded by UC Berkeley students in 2007 and says it has been making at least some algae oil since 2007. How much was not stated. The company claims it will be able to show that it's cost competitive with fossil fuels "in the near term" and that it should be producing commercial volumes of fuel in 2012. It raised $20 million last year. The company uses the method that seems to be most prevalent among the algae companies. That is, it grows select strains of algae in water, strains out the water, and the squeezes the oil out of the algae. An acre of algae can produce about 5,000 to 10,000 gallons of fuel a year, far higher than other feedstocks. Sound easy, yes? Acutally, it's pretty tough. There is only one useable cell of algae for every 1,000 parts of water, according to some researchers. Economically straining out that algae is proving extremely difficult. Some algae companies even admit that to make a profit, they will have to sell the meal -- the part of the cell that isn't oil -- to pet-food producers. Solix, one of the early biodiesel companies, says it can make algae oil right now. It costs about $33 a gallon, although in a few years Solix hopes to produce biodiesel at $3.50 to $1.57 a gallon. (Solazyme, which uses a completely different process that doesn't rely on water, says it will be cost competitive in two to three years.) Sapphire, which hopes to make biodiesel from genetically engineered algae, recently participated in a trial with Virgin Airlines. The algae oil, however, actually came from a Hawaiian company called Cyanotech which claims to be completely against genetic engineering. Could Aurora get there? Sure. Will it be tough? Most definitely.

2009 VC Investment in Greentech VC deals announced in January and February have been percolating since late last year and the economic and investment doldrums have certainly slowed down the pace of VC investment in greentech.  Nevertheless, 2009 is off to a pretty good start with more than $500 million in Greentech VC investments in the first two months of the year. VC Investment in Greentech 2005–2009 Year            VC Investment         Number of Deals 2005            $820M                       74 2006            $2350M                     124 2007            $3478M                     222 2008            $7584M                     350 2009 ytd      $540M+                     39 For more details on VC investment activity in renewable energy -- subscribe to the Greentech Innovations Report.

Tendril Networks is bringing its home energy monitoring and control software to Web-enabled mobile devices — and it's opening it up to would-be application developers around the world. That's the news out of the DEMO conference on Tuesday, where Tendril — maker of hardware and software to monitor and control power usage of TVs, lights, air conditioners and other in-home electricity using devices — has unveiled its new mobile Web application. Other home energy monitoring companies — Greenbox and Trilliant among them — are also working on mobile applications. Tendril, however, has announced it will open its mobile API, called Tendril Vantage Mobile, to third party developers — potentially opening the floodgates to a host of interesting ways to measure and manage a home's energy usage. It's a bit similar to what Tendril did last month, when it opened up its Tendril Residential Energy Ecosystem (TREE) software platform to third-party developers (see Tendril Targets Meter Makers). "The first component is being able to have a window onto your (energy) consumption, and the second thing is being able to turn things on and off," Tendril CEO Adrian Tuck said. But by opening up the platform to developers, "we’ll now start to see a whole raft of things being developed," he said. Of course, Tendril and others in its field don't yet have a market for these mobile home energy control applications. Right now Tendril is involved in about three dozen pilot tests with utilities, and only a few homeowners involved in those tests will be able to use cellphones for things like viewing energy usage and setting programs for turning lights and appliances on and off (see Tendril Expands its Reach Into Smart Homes). But utilities around the country are busy installing hundreds of thousands of smart meters, many of which are set up to communicate with in-home devices. With a host of companies — including recent entrant Google with its PowerMeter offering — now promising to follow up on those smart meter deployments to bring consumers tools to help them measure and reduce the energy they use, taking those tools mobile is the next logical step, Tuck said. He envisions tools like GPS trackers that automatically shut off home lights and appliances when people walk out the front door, or presets that turn on air conditioners as people head home from work. But "The key here is, nobody knows yet what is the right way to talk to consumers about how to manage their consumption," he said. "It’s wide deployment to tens of thousands of homes that will tease out which aplications help consumers save." Google apparently feels the same way. The Internet search giant has said it will open its PowerMeter home energy monitoring platform to third-party developers.

Solar Millennium and NV Energy plan to develop a 250-megawatt solar thermal power plant in Nevada.

Solar Millennium, which has been developing solar-thermal power plants in Spain, said Tuesday it has signed a memorandum of understanding with NV Energy, a utility that serves roughly 2.4 million people in Nevada. The plan is to build the solar-thermal power plant in Nye County by 2014.

The project would be done by the U.S. subsidiaries of Solar Millennium, a technology provider in Germany, and MAN Ferrostaal, an engineering and construction firm also in Germany. The companies, along with NV Energy, hope to start construction in 2010, pending approval from the Nevada’s Public Utilities Commission.

They are still figuring out how to pay for the project. NV Energy could invest money in the project or sign a power-purchase agreement instead, said Britta Carlson, an NV Energy spokeswoman.

A number of European companies with experiences in building solar-thermal power plants are developing projects in the United States, particularly in the Southwest. Solar-thermal power plants use the sun’s heat to generate steam for running an electricity generator, and proponents say solar-thermal technologies can deliver cheaper solar power than power plants built with photovoltaic panels.

Spain has been a popular place for building solar thermal power plants. Solar Millennium has built them there, along with its Spanish competitors Torresol Energy, Abengoa Solar and Acciona Energia.

Acciona completed a 64-megawatt solar-thermal plant in Nevada two years ago called Nevada Solar One, which the company touted it as the largest solar-thermal plant to be built in 17 years and the third largest in the world. Acciona sold the electricity from the $266 million plant to Nevada Power and Sierra Pacific Power, both of which began operating as NV Energy in 2008.

Solar Millennium’s project in Nevada calls for studying the feasibility of adding an energy storage component to the power plant. Energy storage makes an attractive addition to a solar energy power plant, which can only produce electricity during daylight. Using batteries is too expensive, and renewable power companies are exploring other ways to generate electricity after the sun goes down or to store the excess electricity produced at night (such as wind power) for use during the day.

A solar-thermal storage tank would contain superheated materials, such as molten salts, that can be released to generate steam whenever electricity is needed.

With the radical shifts at OptiSolar and eSolar, it's pretty safe to say we are living in the dotcom era of greentech. Not the good part of the equation where money is flowing and everyone is a billionaire on paper. We're in the downside of the era, where companies will have to shrink, change their business plans and in many cases go out of business. Boom and bust cycles have existed for centuries. What makes the particular era more dotcom than most, however, is the prevalence of companies that seem to exist mostly on opportunity, hope, connections and marketing. That's not necessarily a bad thing. However, managerial expertise and "execution" can be difficult foundation upon which to grow a business, particularly in a such a research-intensive world like energy. In other words, these are companies whose selling point is the "Silicon Valley Model" rather than a product itself. Remember Imperium Renewables, the biodiesel company backed in part by expertise from the software world? They were an early signal of the trend. Take OptiSolar. The company was only founded in 2005. By 2007, it had signed two of the largest contracts ever to build and maintain solar energy power plants. By 2011, it wanted to have a factory that would employ 2,000 and cover one million square feet, making it one of the largest PV manufacturers in the U.S. Arnold Schwarzenegger came to open their factory. OptiSolar was on 60 Minutes. The rapid rise, however, was not based on superior technology or a secret sauce. OptiSolar's panels and manufacturing process is somewhat generic. If you wanted a polar opposite of First Solar, it's OptiSolar. Approximately two weeks after the 60 Minutes profile, the company laid off half off its staff. Now eSolar. The company grew out of a earlier project to build solar thermal systems on residences. It then shifted to developing power towers, similar to what BrightSource engineers had been working on for years. It got money from Bill Gross, he of Idealab. It then got money from Google (which a few weeks later also invested in BrightSource). eSolar promised to deliver the cheapest solar thermal technology in the world. A great ambition, but without Bill Gross and Google, would it have received the same level of attention. The interesting part is that OptiSolar and eSolar are likely the lucky ones. OptiSolar sold many of its assets to First Solar (savor the irony) and eSolar sold the rights to projects to NRG Group and will continue to sell equipment. So who's next? Concentrator companies. The number of solar concentrator companies has mushroomed in the past three years. Most have technology that is tough to distinguish from nearby competitors. The market in many ways boils down to "my Fresnel is better than yours." Worse, utilities have signaled they don't have a lot of interest in concentration for now. Expect some of the biggest collapses here over the next six months. Algae. Four years ago, there were only a handful of algae companies -- Solazyme, GreenFuel Technologies, LiveFuels, Solix. Now there are over 50. Most say they will grow algae in bioreactors. I even heard of one outfit, concocted on Wall Street several months ago, that wants to take its real estate expertise to become an algae power. Many of the new companies will shift into becoming "equipment providers" or will offer "complete growing solutions" instead of making fuel. Those listed above seem far better positioned than most to survive. The CIGS companies -- HelioVolt, Nanosolar, Solyndrya, SoloPower -- are all coming to market during one of the worst downturns in years. Even more ominous, they will have to compete against well-funded CIGS and CIS efforts from the likes of Honda and BP. Some of them may not make it. In the defense of the CIGS companies, all of them have deeply invested in technology and R&D. There's not a member of the list above that got into the market by merely latching onto an idea. Hence, expect to see collapses, but not necessarily dot com style meltdowns. Electric car companies. This is another one of those situations where a multitude of companies are chasing a market that makes a lot of sense on paper. Too bad it doesn't exist yet. Think, the Norwegian commuter car company, could become the first victim. Better Place could also face tough times -- electric filling stations again are a great idea, but they may not be needed until 2017. By then, the money could have run out. Although some see Tesla Motors as an example of Silicon Valley excess, in my opinion they've actually seem to have made the transition into a real car company. They are producing cars, have hired industry veterans and are selling product. Tesla also came up with the idea of getting around the high expense of batteries by focusing on sports cars first. It was a genius move. Thus, if they fail, it will be because the challenge was too great.