The Year in Energy

Advanced biofuels, more-efficient vehicles, and solar power top the most notable energy stories of 2007.

The Rise of Biofuels
Corn ethanol production has grown so fast, driving up corn prices and driving down the price of ethanol, that some producers are having trouble breaking even. But an energy bill signed into law last week that requires greater use of biofuels will provide new incentives for both production of biofuels and research into new technologies. Reaching the ambitious goals set by the law will require new technologies for transforming biomass into fuel. (See "Oil from Wood," "Breaking Ground on Cellulosic Ethanol," and "BP's Bet on Butanol.") Others are developing ways to convert biomass into hydrocarbon fuels that could be more practical than ethanol. (See "Making Gasoline from Bacteria.") In the current print issue, Technology Review's editor takes a close look at the technology needed to replace a significant part of gas consumption with renewable fuels and the costs of doing so. (See "The Price of Biofuels.")

Stem fuels: A big story this year has been the ongoing development of ways to turn biomass, such as the corn stems and leaves shown here, into ethanol and other transportation fuels. Credit: Bob Allan, NREL

Cheaper solar panels
Investors are rushing to pour money into solar energy companies to capitalize on an industry that's growing by leaps and bounds. That brought good news for solar technology this year, as the wraps came off a number of technical advances that could eventually make energy from the sun as cheaply as conventional sources. These include new types of panels that use cheaper materials or cheaper manufacturing techniques. (See "Making Cheaper Solar Cells" and "Solar Power at Half the Cost.")

One company in particular, San Jose-based Nanosolar, attracted attention for its decision to build an enormous manufacturing facility for making inexpensive thin-film solar panels (see "Large-scale, Cheap Solar Electricity"), only to see delays in production. But by the end of the year the company had started manufacturing solar panels for its first customer.

Researchers are also investigating more distant possibilities for solar, including using the exotic physics of quantum dots and mimicking the complex chemistry of photosynthesis to help make solar power ubiquitous. (See "TR10: Nanocharging Solar" and "Supplying the World's Energy Needs with Light and Water.")

Managing Carbon Dioxide
Researchers are making progress in finding ways to use carbon dioxide as a source of raw materials for fuel, by taking a cue from biology. (See "Making Gasoline from Carbon Dioxide" and "Turning Carbon Dioxide into Fuel.") But these technologies are still far from eliminating the need to sequester large amounts of carbon dioxide in order to reduce greenhouse emissions. (See "The Precarious Future of Coal.")

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Clearing the Way for Alternative Energy
If alternative energy sources such as wind and solar are ever to provide a big chunk of our electricity, we'll need a better system for storing and distributing that power. That's because these sources of energy, unlike coal or nuclear power, are intermittent: solar panels only make power when the sun shines. New battery systems (see "Fixing the Power Grid") and thermal storage systems (see "Storing Solar Power Efficiently") could help.

More-Efficient Vehicles
GM made news this year with its plans for a new electric vehicle that gets extended range, compared to other electric vehicles, from an onboard generator. (See "Electric Cars 2.0.") Other companies are developing similar vehicles. But technologies for boosting the efficiency of conventional internal combustion engines could play a big role in helping automakers meet new fuel economy standards. (See "The Incredible Shrinking Engine" and the blog, "Better Fuel Economy on the Way.")