Wind power is one of the cleanest and most plentiful sources of renewable energy on Earth. But finding where to place wind turbines can be challenging. Local governments and citizens concerned with the appearance of wind farms and possible reductions in property values often nix good location prospects. And, in heavily developed areas, there may be no place to put a turbine where it won’t be blocked by existing buildings.
Now, a team of Spanish and British engineers has released data that could make locating turbine sites a bit easier. The big thinkers suggest building turbines into the underside of already existing bridges.
The engineers studied the Juncal Viaduct, a car bridge on the Spanish island of Gran Canaria. They created computer models and determined how much wind energy the bridge could produce if equipped with turbines. Running different configurations of turbine numbers and sizes, the model suggested two medium-sized turbines would be the best solution for most bridges. The largest wind turbines currently on the market have blades of about 260 feet across.
For the Juncal Viaduct model, two turbines would produce about 0.5 megawatts of wind power. This could cover the energy consumption of about 500 homes and save 140 tons of carbon dioxide per year, which equates to the amount produced by 7,200 trees in that time.
Though the project remains conceptual—no one has yet attempted to put a turbine beneath a bridge—researchers say it could be implemented anywhere as soon as someone chooses to do so.
“This can be done in any place where you have enough wind,” says Oscar Soto, a mechanical engineer working on the project. Generally, wind speed needs to be between 6 and 25 meters per second to be successful. (For an idea of what average wind speeds are like in the US, check out this map from the Department of Energy.)
The project was spearheaded by the Spanish sustainable energy company ZECSA, with headquarters in the Canary Islands. The findings were recently published in the journal Renewable and Sustainable Energy Reviews.
This isn’t the first time the public has pondered putting turbines under bridges. In 2011, winners of an Italian green design contest proposed turning an abandoned bridge into a sustainable energy factory capable of powering 15,000 homes by fitting solar cells into the road and 26 turbines underneath. The design drew international attention, but remained conceptual. The Juncal Viaduct project represents the kind of hard data necessary to draw investors.
In the United States, about 4.5 percent of all energy needs are currently met by wind power. The country’s wind power capacity was 61 gigawatts as of 2013, enough electricity to power 16 million homes for a year. Over the past decade or so, about a third of all new electricity generating capacity has come from wind installations. As the wind energy sector continues to grow, finding places to put new turbines will be increasingly challenging. Some states are looking to offshore wind farms, which benefit from strong, consistent ocean winds but are more expensive and difficult to build and maintain.
Under-bridge turbines could help bring wind power to areas where it’s previously been considered impossible, Soto says.
ZECSA is currently in talks with Canary Islands officials about making the Juncal Viaduct turbines a reality. Soto thinks thinks construction could happen in about a year or two. From there, the sky (or the wind) is the limit.
“As the evolution of the technology improves, I think it’s going to become common in many places,” he says.