Ice jams and bird and bat deaths will determine the answer
Aside from a small pilot program along the coast of Finland, offshore wind turbines have not been placed in waters that freeze during winter. Moving ice can act like a battering ram, pushed by storms and unpredictable currents, knocking into masts that hold up spinning blades. A major test could be coming soon in Lake Erie near Cleveland. If the six turbines in the Icebreaker Windpower project are built, they could usher in a new era of offshore power in freshwater lakes, rather than salty coastal seas, which has never been done.
The Ohio Power Siting Board has given preliminary approval to Icebreaker, to be built by the nonprofit Lake Erie Energy Development Corp. (LEEDCo). And the Ohio Environmental Protection Agency has ruled the installation complies with federal standards relating to water pollution. Final approval could come this fall, and the turbines could be operating within three years—if objections from concerned groups are satisfied.
Icebreaker would be the second offshore wind farm in the U.S. The Block Island Wind Farm—13 miles off the Rhode Island coast—began generating electricity in December 2016. The $126-million project in Lake Erie would eventually be owned by Fred.Olsen Renewables in Norway, which has 23 operational and planned wind farms (onshore and offshore) in four European countries. The Lake Erie turbines would produce about 21.7 megawatts of electricity, enough for about 7,500 homes. The 200-foot blades would rise 479 feet at their highest point from the water’s surface.
Enthusiasts say Great Lakes wind energy has some advantages over Atlantic coast locations: shallower floor depth, smaller waves, no hurricanes, electrical grids close to shore, fewer effects on commercial fishing and competitive wind speed. If Icebreaker succeeds, they think hundreds of Lake Erie turbines could follow.
The key to success will be how well Icebreaker deals with what Ohioans call the “ice shove.” Winter winds and water currents push thick ice sheets around, at times piling them 30 to 50 feet high close to shore. The sheets are known for wreaking havoc on waterfront infrastructure. Can the wind turbines survive?
Slow Start
The Icebreaker project had been held up for several years because of concerns the turning blades would kill too many birds. The plan was tentatively approved in July after Oho regulators finally determined there would be “minimum environmental impact” to wildlife. They did add more than 30 environmental caveats (pdf) Icebreaker will need to address, most of them related to bird safety.
The persistent issue has been whether the turbines would adversely affect migratory birds on the eastern edge of the Mississippi Flyway. As part of the approval agreement, LEEDCo must develop and install sophisticated radar-monitoring equipment in the lake before construction begins to determine how the wind turbines might affect birds and bats. The company has already done migratory bird studies and found the impact would be minimal. A U.S. Geological Survey ornithologist found an estimated 21 to 42 birds and 21 to 83 bats would be killed by all the turbines annually. The U.S. Fish and Wildlife Service wrote in March that Icebreaker “has limited direct risk to migrating birds and bats.”
Environmental organizations have been split on this issue. The Sierra Club, The Nature Conservancy, Ohio Environmental Council and Environmental Defense Fund back Lake Erie offshore wind as a better alternative for wildlife than the more than 20 coal- and natural gas–fired power plants operating in Ohio. The American Bird Conservancy and Ohio-based Black Swamp Bird Observatory, however, have opposed the plan because they contend (pdf) the wind farm would result in much higher aviary and bat deaths.
The National Audubon Society supported the addition of migratory bird monitoring to “set the standard for wind energy development, if any, in the entire Great Lakes.” One species that needs to be monitored and protected, according to Audubon, is the red-breasted merganser, a diving duck that can be found on Lake Erie in the late fall.
The Ice Test
Whether the tall turbine masts can survive ice sheets comes down to two primary innovations: Lake Erie is the shallowest of the Great Lakes, and averages about 78 percent ice coverage each winter, the highest of the five lakes. The ice challenge will differ from that faced in the Baltic Sea, however. Frozen saltwater tends to hang more below the waterline than does frozen freshwater, which floats on top. Icebreaker will install an inverted cone on the towers at the water level. The idea is that by tapering from a wide flare higher up on the mast down to a narrow base at the waterline, the cone can deflect ice flowing toward the masts, pushing it down and away. Engineers at Finland’s Tahkoluoto pilot installation installed similar cones for their surface ice. Engineers were watching last winter to see how the masts would do, but the weather was mild and there was little ice shove.
The second innovation that will be tried on Icebreaker involves how the masts will be attached to the lake floor. The “mono bucket,” a suction cup–style, circular steel bucket, 56 feet in diameter, will form the foundation. Dropped face down to the bottom from a barge, air and water will then be pumped out of the hollow inside, causing the cup to get pulled solidly into the lake bed a few meters deep. The natural pressure then holds it in place. The process takes a few days instead of the few months needed to install a conventional offshore turbine foundation. This approach has been used a half dozen times in deeper European coastal waters but experts think Lake Erie’s shallowness (60 feet at the turbine site) and lesser wave action is an even better fit, because stress on the foundation will be less. The unanswered question is whether the mono buckets will hold up as the anchor for a mast that might get rocked by ice for about four months each year.
If the bucket handles Lake Erie, it could be sought for wind farms proposed along the U.S. east coast. Willett Kempton, a professor in the University of Delaware’s School of Marine Science and Policy, says that is because the depth of the Atlantic Ocean’s continental shelf there is generally between the depths of Lake Erie and the North Sea.
Price Will Prevail
Building wind farms offshore is still more expensive than erecting them on land, and the price of electricity produced offshore has been higher because of that. Block Island has been selling electricity to the mainland grid for 24.4 cents per kilowatt-hour (kWh), which is high in general—but a future Maryland project is guaranteeing 13.2 cents. Some European companies sell wind power from the North Sea below 10 cents. The average electricity price in the U.S. is about 13 cents per kWh, but the cost varies quite a bit from state to state. LEEDCo says its price will be “well below” that of Block Island’s, but adds it cannot be more specific at this time.
Whether Icebreaker could succeed economically may be more of a regional matter. The Midwest has ample natural gas resources and coal-fired power plants, and onshore wind turbines are moving in from the west. Those factors make the price of electricity in the Midwest generally cheaper than it is in the Northeast. Turbines in the Great Lakes region also may struggle to compete. “I don’t see much future movement in offshore wind after this Lake Erie project,” says Charles Standridge, professor of engineering at Grand Valley State University in Michigan, who has studied offshore wind viability in Lake Michigan. Open space for land turbines, battery storage improvements and increased solar power make Midwest energy production very competitive right now, Standridge says. Unless Great Lakes offshore wind producers can drop the costs “rapidly,” he says, “it is likely going to be pushed aside for a while.”
Still, the Icebreaker organizers are anxious to see how things play out. “We really believe that this little project will open some eyes about what is possible” in freshwater lakes, says David Karpinski, vice president of operations. “Costs will come down…and Cleveland businesses will see the value in this as a game changer in the local economy. People everywhere want cleaner and more reliable and cheaper energy, and this project will show the value of doing that in the Great Lakes.”
Credit: Chris Laurens Getty Images
Source: https://www.scientificamerican.com
Social Media Development addict, Ashley Reyes is specialised on Emerging Techs & Crowdfunding Market. Ashley holds a Bachelor in Marketing and have 5+ years of experience in leader company as Marketing Intelligence Analyst . She is now Chief Community Officer at Athis News.
