The last few years have seen tremendous growth in solar thermal power plants—huge arrays of mirrors that concentrate the sun's energy onto a liquid which then boils and spins a turbine. The process is generally more efficient than using photovoltaic panels, and new solar thermal plants under construction in Spain and Australia will be among the largest capacity solar plants in the world. Old-fashioned PV panels were starting to look archaic, or at least suitable only for small-scale projects like roof instillations. But not all PV panels are created alike.

Here's one for your "only in California" file: A judge has ordered a Sunnyvale couple to cut down two of the eight redwood trees on their property because they block sunlight access to their neighbor's solar panels.

About six years ago, Mark Vargas complained that eight redwood trees on Richard Treanor's and Carolyn Bissett's property were blocking sunlight to the $70,000 worth of solar panels he built to power his house in 2001. To protect his investment, Vargas cited the obscure Solar Shade Control Act that requires homeowners to keep their trees from shading more than 10 percent of a neighbor's solar panels between 10am and 2pm, peak hours for collecting sunlight. The judge ruled in favor of Vargas, although he decided against fining Treanor and Bissett the up to $1,000 a day in violations allowed by the law.

We told you about a new ultra-black material back in January and guess who was the first group to come knocking on the researchers' door?

It's going to be at least another two decades before any commercial models are built, but researchers are at work designing the Generation IV nuclear reactors. Unlike the generation II and III models now in use that use water to cool and control the fission (preventing runaway reactions, subsequent meltdowns and the environmental apocalypse that would result), the leading contender for cooling material for the Gen IV reactors is molten sodium. Not sodium chloride (plain, unreactive table salt), but sodium metal.

A panel convened by the National Academy of Engineering announced today a list of the most important projects in the world—at least, what would be, were we to figure out how to build them. The 14 priorities range from economical solar power—we only need to harness 1/10,000th of the sunlight that hits Earth to satisfy the world's energy needs—to reverse-engineering the brain and universal access to clean water (see the full list after the break). They're also introducing a slick new website to solicit public opinion. What do you think is the most important engineering challenge for the century to come?

Running the hot water for five minutes burns as much energy as leaving a 60W light bulb on for 14 hours, according to Peter Gleick of the Pacific Institute.

"Cellulosic ethanol technology is a lot closer to reality than a lot of articles would have you think," said Jacques Beaudry-Losique, manager of the Department of Energy's Biomass Program this morning at the American Association for the Advancement of Science meeting. After some well-publicized studies stated that corn-based biofuels might exacerbate CO2 damage to the environment, focus has shifted to these so-called "second generation" biofuels that use non-food crops such as switchgrass, wood chips or crop residues (e.g. all the parts of the corn plant that are currently wasted after harvest--the stalk, leaves and "cob").

Take a peak inside the Solix labs to see their oil-from-algae operation up close in our photo gallery and video

“Here it is!” Jim Sears says with a tour guide’s come-see enthusiasm.

It sounds as if someone just dropped a tricycle into a meat grinder. I’m sitting inside a narrow conference room at a research facility in Bristol, Connecticut, chatting with Joseph Longo, the founder and CEO of Startech Environmental Corporation. As we munch on takeout Subway sandwiches, a plate-glass window is the only thing separating us from the adjacent lab, which contains a glowing caldera of “plasma” three times as hot as the surface of the sun.

Big lumps of sooty coal hardly seem like the future of energy, but that's exactly what the U.S. Department of Energy predicts. Consumption of the fossil fuel-the main source of greenhouse gas and a major contributor to acid rain, smog and mercury poisoning-will hit 10.6 billion tons a year by 2030, a near doubling of the 5.4 billion tons burned in 2003, according to the agency.