|
Trying to bottle sunshine
Source: Alternative Energy
By Chris Spitzer
An ocean of clean energy pours from the sky. We could forget about non renewable climate-altering sources, like gas, oil and coal, if we could fill the tank or power our homes with a sunbeam. Current solar technologies aren't quite up to that task. Conventional solar panels are inefficient; electric batteries are expensive and can't store enough to light a city through the night. If only the sun's rays could be converted into an easily stored fuel.
But how do you bottle sunshine?
The Hydrogen Club at Oregon State University is on a mission to develop new technologies to tap the sunshine. Inspired by processes that already occur in nature, they've found several surprising biological and chemical ways to make hydrogen fuel.
Hydrogen is a near-perfect way to store the sun's energy. It emits only water vapour when burned and can be converted into electricity using a fuel cell. And it's practically limitless -- an hour of sunshine has enough energy to power the planet for a year.
The need is exploding. The Department of Energy projects a 50 percent increase in worldwide demand by 2030. To provide that much power with conventional technology, we would need to open two new coal, gas or nuclear plants every day for the next 20 years, says Roger Ely, Oregon State professor and adviser to the
club.
"Everybody is kind of locked in that vision of the world we've experienced for the last 100-plus years," Ely says, but the club looks in a new direction.
Because the sun shines everywhere, the club wants to make hydrogen from solar energy right where it's needed. Their new technologies can be integrated directly into individual homes and neighborhoods, powering them without the distant power plant. That notion is as revolutionary as replacing large centralized mainframes with personal computers was in the early 1980s.
A place that gets year-round sunshine, like Arizona, needs different energy tools than one that's often overcast, like Oregon. The members of the Hydrogen Club are exploring three promising directions.
Bacteria may be an answer. They have a huge head start when it comes to capturing the sun.
"Nature's been doing R&D for about 4 billion years or so," says Ely, whose group works with cyanobacteria, a microorganism that produces hydrogen as part of photosynthesis.
The bacteria can do tricks that engineers struggle to reproduce. "They do particularly well under low-light conditions," says David Dickson, a graduate student in Ely's lab. "In fact, they do better when they're not receiving blasting direct sunlight."
This means bacteria-based solar panels could hang on all sides of buildings and would work even on cloudy days. In nature, though, bacteria generate only a trickle of hydrogen. But with small changes to the environment that bacteria live in, the Oregon State lab has attained a 600-fold increase in hydrogen production.
While they work to increase production even further, Ely and Dickson have started to look at commercial applications. Dickson is working to embed bacteria into a solid substance called sol-gel, in which the cells remain alive and active for months. They imagine large sheets of the gel could be turned into hydrogen-producing panels and supply energy for a home or office building right on site.
For spots that get a lot of direct sunlight, Oregon State Professor Alex Yokochi and graduate student Nick AuYeung believe chemistry may be the best approach.
They work on ways to convert heat into hydrogen.
"The input power would be solar," Yokochi says. Banks of curved mirrors, each a few feet wide, could be installed in neighborhoods to concentrate sunlight.
Certain chemical reactions happen only when it's hot. At about 1,000 degrees, a series of steps that convert water to hydrogen becomes possible. Numerous chemicals are involved, but the process forms a cycle so everything is reused -- no byproducts, no pollution.
"Sort of like a black box," AuYeung says, "you put your water in and you apply some heat." The size of tractor-trailers, these boxes -- self-contained chemistry labs -- would simply provide a clean stream of hydrogen fuel.
The devil is in the details, though. The cycle, discovered 30 years ago, has never been implemented on a large scale. Some steps "suffer from problems of corrosion and inefficiencies," Yokochi says. His lab explores small, simplifying changes to make the complete cycle more efficient. The goal is a neighborhood system that would function like a generator.
"Let's say you live in Eastern Oregon," Yokochi says. "You have a lot of potential solar thermal resource so you could locally produce hydrogen."
Though it's not how people usually think of it, sewage is really just an unpleasant form of solar energy. The organic molecules that make up sludge originated in plants that absorbed sunlight, if you trace their histories back far enough.
Normally it takes energy to clean up wastewater, but Oregon State Professor Hong Liu has a better idea. "You can not only clean the environment," she says, "you can also get energy from it."
Some natural microbes can decompose organic matter into its pieces, including hydrogen. She built a "microbial fuel cell" that takes in wastewater, uses the tiny creatures to break down the waste molecules, and sends out a stream of clean water, as well as hydrogen.
So far Liu has only built jar-size cells in her lab. The next step is to design an industrial-scale machine big enough to handle home septic tanks or city water-treatment plants. Then, they need to develop a method to capture and store the hydrogen that's produced. "That's where we're heading," says Liu, who predicts the technique will be applied within the next decade.
Many universities are working on pieces of the hydrogen puzzle. The biweekly meetings of the club give members a chance to weave their individual efforts into a long-term vision.
"Day in and day out, we're focused on minutiae," Dickson says, "but the club gives us an opportunity to step back."
What the club see is a world hungrier for power every day. A few decades is not much time to research new technology, find ways to integrate it into the infrastructure, and shift to a new energy source.
At the federal level there's not a unified plan for hydrogen research -- or monetary commitment, according the Oregon State club, which gets limited funding through public and private grants.
"We should do something on the scale of the Apollo project or the Manhattan project," says Ely, "because this is a national priority and we need to do
|
|
