Most people think wind power and solar power are competitors, but Sarah Kurtz of the U.S. Department of Energy’s National Renewable Energy Laboratory says that the opposite is true. “Wind resource tends to complement solar resource,” says “Here in Colorado, for instance, the windiest time is during the winter and spring months. In winter, we don’t have as much sunshine, but we tend to get more wind and stronger wind.”
In Australia, the Australian Renewable Energy Agency (ARENA) has invested A$9.9 million in a 10 megawatt solar farm adjacent to 73 wind turbines that are already online. The co-location of solar and wind provides more continuous energy generation than having either technology working alone. Co-locating wind and solar plants can save money on grid connections, site development, and approvals, says ARENA CEO Ivor Frischknecht. Putting the Gullen Solar Farm adjacent to the existing wind project will result in savings of as much as A$6 million. That means a 2-% reduction in cost of the project.
“Scale isn’t as important for competitiveness when plants are co-located, meaning the approach could also unlock new markets for medium-scale solar PV projects,” he says. How big are these new markets? A study funded by ARENA found an estimated 1,000 MW of solar generating potential at existing wind farms in Australia — enough to power 700,000 homes. “The lessons learned at Gullen Range will be invaluable, as this is the first project of its type in Australia,” Frischknecht says. “It has the potential to cement industry confidence in the approach and provide a blueprint for similar projects to follow.”
There are other financial benefits to locating wind and solar together says NREL’s Kurtz. Combining solar and wind can help cut battery costs as well. Adding wind can help cut battery costs, since the wind can (and often does) blow when the sun doesn’t shine. “If you’re in a location where the wind does blow, and especially where the wind complements solar, until the batteries get cheaper than the wind power itself, you’re going to be better off adding wind [than batteries],” Kurtz says.
A microgrid will still need some form of storage, “because there will always be a night when the wind isn’t blowing,” she adds. But the solar and wind combination “can make battery demand much smaller.”
In Texas, the Defense Logistics Agency of the U.S. Department of Defense is taking a slightly different approach to supplying all the needs of Fort Hood with renewable power. It is combining electricity generated by solar panels on the base itself with electricity generated by a wind farm 300 miles away.
The Army wanted the grid security provided by local generation that isn’t vulnerable to power outages and other transmission constraints but chose to site the turbines where the wind resource was the strongest. The setup illustrates the point that “[a] hybrid project does not necessary have to be co-located,” says Dahvi Wilson, public affairs director for Apex Clean Energy which is developing the system for Fort Hood.
Wilson is enthusiastic about how the projects helps make these renewables make sense from an economic as well as environmental standpoint.
“Wind energy offers the cheapest option for new energy construction currently available in the U.S., while solar energy can be more expensive to develop and install,” Wilson explains. “By combining the costs into one product, the blended cost is competitive with other new sources of energy.”
Perhaps one day, grid storage batteries will be so cheap that their cost will be no concern. Until that day, combining wind and solar resources may often create the most amount of electricity for the least amount of money.