Among the many innovative technologies we’ll see in the near future, here are a couple of innovative uses for solar coming down the pike: solar energy beamed down from space and solar used to recycled carbon dioxide into fuel.
These and hundreds of other technologies we can barely imagine today offer solutions to our climate change challenge – if we can cross the threshold and put a price on carbon through US legislation and if countries take a stand and commit to moving forward to a prosperous, green economy at Copenhagen.
Solar from Space?
Yes, the first contract for beaming solar energy from space has been approved.
As part of its effort to obtain 33% of electricity from renewable energy sources by 2020, the California Public Utilities Commission (CPUC) approved the contract. California utility PG&E will receive solar energy generated by Solaren Corp’s orbiting satellites through a long term power purchase agreement. Solaren says it can provide 1700 GW-hours of energy a year for the 15-year contract, which starts in 2016.
Once the 200 MW solar plant is hoisted into space (no mean feat) it has the advantage of 24-hour a day sunlight. No clouds to worry about. The day/ night cycle of the earth is irrelevant. Solar cells in space would capture about five times more energy as that on earth. It would also be possible to beam solar anywhere in the world, especially useful for regions that lack sunlight – and getting permits to build on sensitive lands isn’t a problem.
Can Solaren do it? The founders are veterans of Hughes Aircraft, Boeing and Lockheed so it has a shot. Although the price tag will be several billions of dollars more than for a similar sized earth-based solar plant, Solaren believes they can bring costs down by light-weighting the system. PG&E didn’t disclose the price of the power purchase agreement.
Here’s how it works: a Mylar mirror, about a kilometer in diameter, would be inflated and float freely once it reach its orbit. From there, sunlight would be concentrated onto smaller mirrors, which would focus the light on PV modules. The resulting electricity will be converted into radio frequency energy that’s transmitted to a receiver station on the ground. After the radio waves are converted back into electricity, it’s fed into the grid.
The company plans to start launching components into space for testing in 2012. The construction of the plant will be subcontracted to the aerospace industry. It’s not a big risk for PG&E because they only pay when they receive electricity.
Japan’s Aerospace Exploration Agency (JAXA) is also working on a solar power space station – by 2030. Research has been underway for 10 years – the plan is to put a 1 GW solar unit into orbit that generates electricity for about 8¢ per kilowatt hour. Rather than siting the receiver on land, the energy would be transmitted to floating "lily pads" in reservoirs or in the ocean via microwaves. One satellite is set to launch around 2013, which would evaluate the microwave transmission device and any negative impacts on the environment.
Costs are the biggest obstacle. Solaren continues to raise funds for the pilot project. The way to bring down costs, of course, is to build to scale and produce a lot of electricity – that requires large rockets. Solaren’s vision is to follow this pilot with 1000 MW plants – as big as nuclear plants, but that produce cheaper electricity.
Marty Hoffert, a physicist at New York University, told Space that solar space technologies can deliver energy for the same price as those on Earth. Rather, the problem is we always compare the price with that of coal. He’s not so confident in Solaren’s plan and worries that if it fails, it would be a blow to space solar.
Solar for CO2 Recycling?
Another exciting application of solar energy is the potential of using it to recycle carbon dioxide into fuel.
Sandia National Lab has demonstrated a working prototype of their "Sunshine to Petrol" machine, which uses concentrated solar to reverse combustion of CO2.
The machine uses concentrated solar to chemically "reenergize" carbon dioxide into carbon monoxide and water, which can then be used to make hydrogen or serve as a building block to synthesize "Liquid Solar Fuel" – a liquid combustible fuel, such as methanol or even gasoline, diesel and jet fuel.
Originally, researchers were working on a device that would break water into hydrogen and oxygen, when they realized they could break down CO2 instead of water.
The technology holds real promise is reducing CO2 emissions while preserving the option to use fuels that we’re accustomed to, says Ellen Stechel, Sandia Fuels and Energy Transitions Department Manager. The current oil and gas infrastructure doesn’t have to be modified or re-created as it would to carry hydrogen. In addition to Sandia, DARPA (Defense Advanced Research Projects Agency) is funding the project.
Rich Diver, who invented the machine, says, ""What’s exciting about this invention is that it will result in fossil fuels being used at least twice, meaning less carbon dioxide being put into the atmosphere and a reduction of the rate that fossil fuels are pulled out of the ground." The CO2 produced at a coal or power plant or factory would be captured and then reduced to carbon monoxide in the machine, which could then be used to create any kind of liquid fuel.
Hopefully, in ten years time, when the machine might be ready for commercialization, power plants and factories will have significantly reduced carbon emissions. If so, what’s left would be recycled and they would have a new revenue stream for carbon emissions.
Most exciting is the prospect of capturing CO2 that’s already in the atmosphere and turning that into fuels, which is the project’s long term goal.
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