Scientists search a gorge for the secrets of wind

Source: John Fialka, E&E News reporter • Posted: Tuesday, June 27, 2017

A team of researchers looking for ways to expand the use of wind power just finished measuring wind strengths in one of the toughest areas in the world to study it, the gusty, meandering Columbia River Gorge.

The 80-mile gorge between Washington and Oregon amounts to a freeway for winds entering from the Pacific Ocean. It already hosts one of the world’s largest collections of wind farms at its eastern end. According to the Department of Energy, they generate 5 gigawatts of electricity, or more than twice the annual output of Hoover Dam.

The gorge poses a tantalizing question to utilities and the researchers, led by DOE and the National Oceanic and Atmospheric Administration. That is, if the National Weather Service could more accurately forecast the gorge’s daily wind power, the result could be substantially more emission-free electricity across the United States.

“A wind farm can be a heck of a lot of investment,” said Joel Cline, a DOE meteorologist, who is leading the $2.5 million project, “but the fuel is free.” What he hopes to get out of the research is a computer model that is versatile and accurate enough to measure potential wind power anywhere in the United States.

For meteorologists, the field of forecasting daily wind power is only about 10 years old. Earlier weather forecasts focused on wind speed at 10 meters (32.6 feet) above the ground. That was needed for airport takeoffs and landings. Wind farm operators need to know wind speeds at 80 meters (262 feet) and 120 meters (394 feet), the heights of the wind turbine’s hub and the tips of its blades.

The wind is more powerful at those heights, and earlier studies by DOE and NOAA showed that in the relatively flat areas of the upper Midwest and in West Texas, wind farm owners could increase their power output by as much as 13 to 15 percent by using more accurate daily wind predictions.

The information gave utilities more confidence to shut down expensive fossil fuel plants and to rely more on “free fuel” for a promising day, or to sell their excess power to their neighbors. The substantially improved economic picture, the earlier study noted, “suggests that we may have just begun to scratch the surface and further large improvements are yet likely to occur.”

So in 2015, a second experiment, called the Wind Forecast Improvement Project (WFIP-2), got underway with researchers from NOAA, four DOE national laboratories, and several companies and universities. They installed over 100 pieces of wind testing equipment in the gorge, which is anything but flat. It is surrounded by a spiky array of 4,000-foot mountains that create substantial wind “wakes,” or voids that make the winds plowing up the Columbia River very tricky to measure.

The result can be small storms that traditional computer models don’t see and invisible pools of cold air that can slow wind flows, only to speed them up again when temperatures rise. The mathematics that guided flatland wind forecasts can’t cope with conditions in the gorge.

“Computers know about vertical, but not horizontal,” Cline explained.

In the earlier Midwest tests, researchers were aided by wind measurement devices installed on tall towers in the region, but in much of the environmentally protected gorge, there weren’t very many. It helped that wind farms there provided tons of data — usually held as proprietary information — about the winds arriving at the hubs of their turbines on any given hour or day.

But were these winds predictable?

Poems and apparatus

Researchers had a big stew of data, but one with many voids in it. Poets have wondered about some of them for decades. “Who has seen the wind?” asked Christina Rossetti in a popular nursery rhyme in Victorian England. “Neither I nor you:/ But when the leaves hang trembling,/ The wind is passing through.”

Jim McCaa, senior meteorologist for a Finnish company, Vaisala, which coordinated the Columbia River Gorge research for DOE, used tools that Rossetti never heard of.

Researchers manned powerful radars that reflected back signals when they spotted aerosols floating high in the air over the gorge. To the researchers, the aerosols — small droplets of water vapor, or dust, or other matter floating in the air, were like Rossetti’s leaves. Their signals told researchers which way the winds at any given point were moving.

McCaa also had sodars, or devices that sent sound waves out over the gorge and then used powerful microphones that captured their echoes. One of the mysteries swirling in the gorge is big differences in moisture and temperatures in columns of air that might be right next to each other. These created turbulence that could be measured by the sodars.

Then there were lidars, instruments that used pulses of light to track clouds, smoke and other moving objects in the air, producing 3-D pictures of where they are and where they are headed.

Vaisala, McCaa’s company, has a long history of solving weather’s many puzzles. Its founder, Vilho Väisälä, invented the first modern weather balloon in 1930. It was a simple, disposable helium-filled balloon carrying a payload of instruments to measure a given column of air. As it rose, it radioed signals back to the ground describing the atmosphere at different heights.

Meteorologists call them radiosondes, and the National Weather Service had dozens of them at the ready for McCaa around the gorge. “When interesting events would come up, we’d call NWS and they would deploy more balloons,” he said.

The result of all of this was so much data that it will take a year to sort out. “Atmospheric modeling remains one of the classic big computer problems. This is where the national labs come in,” McCaa noted, referring to DOE. “There are few places in the world that have the capacity to pull this off.”

Unlike Europe, which has largely shifted its wind energy resources offshore — facilities that are more expensive to build and maintain — McCaa believes most U.S. wind companies will remain onshore, especially if tests show that wind in complex areas, such as the gorge, can be accurately forecast.

“Relative to Europe, we have a lot of slightly populated areas where we have the space to put more wind projects onshore, which Europe does not have,” he said.

Lazard, the Wall Street financial advisory firm, reported in December that utilities have already gotten the message that wind power has become more cost-competitive. Utilities and others invested six times more in onshore wind power last year than they did in 2009.

“Utilities like Xcel in Colorado are operating on larger amounts of wind energy. Because of the higher accuracy in forecasts, they are able to go to higher levels of wind energy than they thought they could a few years ago,” explained Michael Goggin, senior director of research at the American Wind Energy Association in Washington, D.C.

Meanwhile, he noted, wind turbines are getting taller and using larger blades, and they’re becoming more efficient at