When most people think about changing the way America uses energy, they imagine new ways of generating electricity like solar farms or new nuclear reactors.

But at an innovation summit organized by the Department of Energy's high-risk, high-reward research branch, ARPA-E (modeled after Darpa), it's not just power generation that's getting a makeover. The companies hawking their ideas there, which all received grant money from ARPA-E or were finalists, are trying to reinvent the entire energy system. Everything is getting a technological re-evaluation from the actual wires that power is transmitted on to the waste heat produced in industrial processes.

And of course there are also new ways of making electricity beyond just burning some rocks or oil to create steam to drive a turbine.

Here are 10 companies that caught our attention. Any one technology is unlikely to solve the looming climate change and peak oil problems, but working together within the larger system, they could tilt the globe away from catastrophe and towards a sustainable future.

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Agrivida ——–

Now, ethanol is made with corn cobs, which are just a small amount of the corn plant's total biomass. For years, people have been trying to come up with ways to use all the rest of the plant to make fuel. They call that stuff "cellulosic ethanol," because it doesn't just use the sugars in the cobs, but the cellulose in the rest of the plant. It turns out, though, that it's not so easy to do the chemistry that transforms a corn stalk into a liquid fuel that works.

Agrivida is working on plants that release enzymes to degrade the cellulose in their own cell walls — on command. They throw a molecular switch, and the plants start turning themselves into sugar, saving fuel processors a key and energy-intensive step.

Photo: Theophilos/Flickr

Phononic Devices —————-

Most industrial processes generate heat as a byproduct. Not only does that heat do no useful work, it also damages machinery. But there are materials that can directly convert heat into electricity without running some working fluid through a traditional generator. Phononic Devices is out to make these thermoelectric materials, which have been around for a good while, much more efficient and cheaper through nanotechnology.

If scavenging heat to make electricity gets a lot cheaper, it could increase the overall efficiency of many processes. But to do that, you need much better materials.

"Thermoelectrics is a pure materials field," said Gerbrand Ceder, an MIT materials scientist who is not associated with Phononic Devices. "Thermoelectrics is going to leapfrog forward if you have better materials."

Photo: Bob Jagendorf/Flickr

Makani Windpower —————-

Wind power is already cost-competitive with fossil fuels (.pdf) in many places — and cheaper in really windy places. But it's not perfect. The wind close to the ground is streakier than the stuff higher up, and it doesn't blow as hard. Because the power available in the wind varies with the cube of its speed, a bit more speed gets you a lot more power. The best ground-based sites have a wind-power density of about a kilowatt per square meter of area swept. The wind-power density near the jet stream above New York is more than 15 times better than that.

Makani Power wants to use large kites tethered at high altitudes to take advantage of the better wind resource that exists up there. It sounds crazy, but Google has already invested $15 million in the company.

Graphene Energy —————

Diamonds might be a girl's best friend, but graphene, the one-atom thick configuration of carbon atoms, is every nerd's favorite form of C. Researchers can already imagine all kinds of wonderful applications for the stuff – like bendy electronics – but it might come in handy for energy storage, too.

Graphene Energy is developing ultracapacitors based on the material. Ultracaps are considered a very attractive technology because — unlike your laptop battery — they can be cycled many times over and they can also provide big bursts of power. The problem is that they don't have anywhere near the energy density. Graphene Energy's technology is based on the work of the University of Texas' Rod Ruoff. Ruoff has claimed that graphene could double the capacity of existing ultracapacitors by increasing the amount of carbon surface area that's actively storing energy.

Image: St Stev/Flickr

Superconductor Technologies —————————

The existing power grid has received a lot of attention because it loses some of the electricity that's pumped into it. New, long transmission lines would also be required to get power from windy and sunny places to where people live if those renewable technologies are going to provide large amounts of power in the future.

While many people are focusing on new meters or other "smart grid" ideas, Superconductor Technologies is trying to reinvent the actual power line. Not the idea of it, but the wire itself. They claim that by replacing the copper and aluminum wires in the grid with a ceramic, high-temperature superconductor, the lines could have five times the capacity and waste less electricity.

Photo: Dolor Ipsum/Flickr

Velkess ——-

An energy system that can accommodate the intermittency of renewable power will probably need large-scale storage. Companies are trying to commercialize all kinds of storage technologies, from pumping compressed air into caverns to using new kinds of ultracapacitors.

Flywheels are another promising technology. They store the energy mechanically by rotating mass around an axis. Energy placed into the system by a motor gets the flywheels spinning, and the same motor can be run the opposite way to pull energy out of the system. They are commonly used in industry, but are considered too expensive and immature for deployment.

Velkess has a promising flywheel system that the company claims could reduce storage costs by a factor of 10.

Photo: Sebastiano Pitruzzello/Flickr

Velocys ——-

Biofuels have come under attack as a solution to climate change, but if world oil production has peaked, coming up with a cheap way to make liquid fuels out of something else would still be very important technology. The Fischer-Tropsch process is a well-known way of making synthetic fuels from other types of carbon. In the past, that's largely been coal, such as when the Germans used the process (see the plant above) to manufacture fuel during World War II. But it could also be used with biomass to make biofuel.

The downside to Fischer-Tropsch is that it's an energy-intensive and therefore expensive chemical process. Velocys says it has a better way of mixing the ingredients in the process to bring down the cost of making hydrocarbons out of regular old carbon.

Wildcat Discovery Technologies ——————————

New materials have driven the power industry for decades, as better heat- and pressure-resistant materials allowed electrical plants to grow larger and larger. Now, there are all kinds of new materials that would be nice to have. Better batteries, carbon capture and photovoltaics all depend on the material science, yet it's still a very trial-and-error science. Wildcat Discovery Technologies is trying to bring high-throughput automation to the discovery and synthesis of new materials. Their technology is one way to bring the accelerating advances in robotics and computing to bear on the energy problem.

Photo: Plug-in module for the Nissan Leaf, an electric vehicle.

Jim Merithew/Wired.com

Xtreme Energetics —————–

Photovoltaic panels have to do two jobs, which often come into conflict. First, because sunlight is a diffuse energy source, they need to spread out over a large area as cheaply as possible. Second, they need to convert those photons into electrons as efficiently as possible. Those two tasks call for different kinds of materials. Collecting photons isn't difficult and can be done with cheap materials, but converting them into electrons is really tough. But what if you could separate those tasks? That's the idea behind concentrating photovoltaics technologies like Xtreme Energetics. You use a cheap material to focus the sun's rays on a very efficient, very expensive small piece of photovoltatic material.

Xtreme Energetics says its technology could make electricity at a cost of $1.50 per watt with 43 percent efficiency and a smaller footprint than traditional solar panels.

Potter Drilling —————

Tapping the heat of the Earth has proven a cost-effective way of making electricity in most of the places around the globe where earthquakes are likely. Geothermal reservoirs are like capped geysers: When humans drill a hole, hot stuff comes up, which can be used to run a turbine.

But the big play in geothermal energy has always been to simply use the hot rocks down there and create your own reservoir. To do that, you have to drill into rocks much harder than those you normally encounter in oil fields. Potter Drilling is trying to commercialize a new drilling technique that replaces drill bits with … hot water. The company thinks it can halve the costs associated with drilling enhanced geothermal fields.

Of course, right now, geothermal may have bigger problems than drilling. The bad press over small earthquakes caused by an enhanced geothermal project in Switzerland has taken some of the shine off a technology that had been anointed by a big MIT study as a big piece of out energy future. It's worth noting, though, that the vast majority of human-caused quakes are caused by traditional mining and by hydroelectric-dam reservoirs.