1366 Technologies

Why: Conventional solar power is still too expensive to compete with fossil fuels, in part because of the cost of manufacturing silicon-based solar cells.

Key innovation: Developed a cheaper method for making silicon wafers, the most expensive component of a solar module.

Technology: The process that 1366 has developed makes it possible to mold solar wafers—the thin sheets of silicon that serve as the core of a solar cell—directly from molten silicon rather than cutting them from larger ingots or crystals, which can waste up to half the material. The company has also developed a method for manufacturing solar cells that increases the amount of light the cell can absorb by reducing the area that’s shaded by electron-conducting wires and by decreasing the amount of light reflected off the surface. Increasing the light absorption helps increase the power output of the cell, effectively decreasing the cost per watt.

A123 Systems

Why: Lithium-ion batteries make electric cars possible at mass-market prices.

Key innovation: Nanostructured electrodes result in lithium batteries more durable and safer than those in cell phones and laptops.

Technology: A123 develops and manufactures lithium-ion batteries that are safer than those in mobile phones and laptops and use less expensive elements. The materials are structured at the nanoscale in a way that enables them to charge and discharge quickly, making them well suited for use in electric vehicles and in electrical-grid storage.

Amyris

Why: Advanced biofuels could help reduce the use of gasoline and diesel.

Key innovation: Its genetically engineered yeast turns sugars into a building block of diesel fuel, which is usable in the existing transportation infrastructure.

Technology: Amyris has engineered yeasts that convert sugars into a hydrocarbon molecule called farnesene, which can be processed into fuels for transport or products for the chemical industry. If hydrogenated, the hydrocarbon can be turned into a diesel fuel that burns cleaner than conventional diesel, reducing emissions of sulfur, nitrogen oxides, and particulates. ­

Bright Source Energy

Why: It efficiently produces solar thermal power, which focuses sunlight to heat water into steam.

Key innovation: A boiler is heated directly with sunlight that bounces off mirrors.

eSolar

Why: Reducing the cost of constructing solar thermal plants will make them more competitive with fossil-fuel plants.

Key innovation: Software controls the mirrors that focus rays from the sun, eliminating the need to position them by hand.

Technology: The company uses arrays of tens of thousands of mirrors to focus sunlight on a central tower, producing intense heat that turns water into steam to generate electricity. The mirrors are installed on prefabricated metal frames that allow them to pivot and tilt to track the sun throughout the day and from season to season. Proprietary software ensures that all the mirrors are aimed properly. /td>

First Solar

Why: New types of photovoltaics are reducing the cost of solar power.

Key innovation: "Thin-film" solar panels based on cadmium telluride, which are cheaper than conventional silicon panels, have made the company one of the world's largest photovoltaic manufacturers.

Technology: The leading producer of thin-film solar panels, First Solar has established an alternative to conventional silicon-­based technology. The key is a material called cadmium telluride, which absorbs light better than silicon does; as a result, extremely thin films of the material are all that’s needed.

Goldwind Science and Technology

Why: Increasing the time that turbines are operational will lower the cost of wind power.

Key innovation: Co-developed a direct-drive wind turbine that eliminates the need for a gearbox. Having fewer moving parts reduces the chance of costly mechanical failure. Note: Revenue $1.6 billion

Joule Unlimited

Why: Biofuels could be far cheaper if they weren't made from corn, sugarcane, and other forms of biomass.

Key innovation: Designed microbes that convert carbon dioxide and water directly into fuels.

Technology: Joule has engineered microbes that harness the sun’s energy to convert carbon dioxide and water directly into ethanol or hydrocarbon fuels. When housed in bioreactors in sunny areas and at full-scale production, the company says, these photosynthetic organisms can produce 15,000 gallons of diesel or 25,000 gallons of ethanol per acre per year. The process offers an advantage over making biofuels from corn or cellulose, because growing those materials requires large amounts of arable land. It’s also an improvement over using photosynthetic algae to make biofuel precursors, as some other companies do, because those chemicals must then be processed to make fuel.

Siemens

Why: Increasing the time that turbines are operational will lower the cost of wind power.

Key innovation: Co-developed a direct-drive wind turbine that eliminates the need for a gearbox. Having fewer moving parts reduces the chance of costly mechanical failure. Note: Revenues $103.7 billion.

Silver Spring Networks

Why: Computer intelligence in the electric grid will make energy distribution more efficient.

Key innovation: Developed hardware and software that standardize the way disparate parts of the grid communicate.

Technology: The company builds secure, adaptable network infrastructure that helps utilities and their customers manage their energy use more efficiently. Silver Spring Networks' software allows utilities to automatically manage their distribution of electricity by quickly responding to spikes and lulls in electricity generation and demand, as well as failures in the grid. The company also builds its communication chips into smart electric and gas meters that relay data to a centralized software system. Consumers can access the data to monitor their own energy use through a Web portal that Silver Spring maintains.

Suntech

Why: Extremely large-scale production of solar panels is reducing the technology's cost.

Key innovation: Developed its own solar cells and equipment for manufacturing them cheaply.

Technology: Suntech is the world’s largest producer of crystalline-silicon solar panels, the most common type. It specializes in multicrystalline cells, which produce somewhat less power per square meter than single-­crystal cells but yield a competitive price per watt because the materials cost less. The company’s current generation of solar cells has broken an efficiency record for multicrystalline cells that had stood for 15 years; one key to the accomplishment was to increase the amount of light the cells absorb by texturing their surface and decreasing the thickness of electron-conducting wires.

Synthetic Genomics

Why: Genetically engineered microbes are a promising way to make biofuels.

Key innovation: Created synthetic bacterial cells, possibly paving the way for organisms specifically tailored to make fuels.

Technology: Strains of algae engineered by Synthetic Genomics excrete oils that could be refined to make biofuels, including equivalents of gasoline and diesel. In partnership with ExxonMobil, which has agreed to invest up to $600 million in the project, the company is studying many strains of algae, using high-throughput methods to help identify those that produce large amounts of the desired oils and to reveal techniques for engineering known strains in ways that will increase their oil production.