Powering Tomorrow

Offshore Wind and Solar Energy
Written by Robert Hoshowsky

Fast becoming the poster child of renewable energy, offshore wind and solar power is growing worldwide – but not without controversy.

In March, America’s renewable energy sector received a boost when President Joe Biden announced bold initiatives to “catalyze offshore wind energy.” Vowing to build a clean energy economy and increase offshore wind power generation to 30 Gigawatts (GW) by 2030, the President said that this renewed focus on wind will ultimately create millions of new jobs – especially in Pacific and Atlantic coastal areas, and the Gulf of Mexico – and see an increase in the use of American steel to construct America’s first “compliant wind turbine installation vessel.”

With half of the American population living in these coastal areas and requiring tremendous amounts of power, the plan makes sense for a world shifting away from petroleum and coal-fueled energy to renewables.

Morale boost
The demand for energy remains voracious, even during the COVID crisis. Like every other nation on earth, America’s economy has been battered. And America’s spirit could also do with some good news right now. The Biden administration’s plan would see not only an increase in offshore wind power capacity, but also some 77,000 new jobs in the U.S., 44,000 of them direct, the other 33,000 indirect.

Since the president made this vow, the plan has been both widely praised and criticized. To date, nine states along the east coast of the U.S. – where a dozen or more offshore wind farms are likely to be built – are already looking to the federal government to alleviate potential losses to the commercial fishing industry, a long-time opponent of offshore wind farms.

For the fishing sector the issues are many, ranging from the size of offshore wind farms (standing five times the 171-foot (52 meter) height of the Barnegat Lighthouse off Long Beach Island), to the proposed number of turbines, and the as-yet-unknown impact on fish habitats and local economies.

Residents of areas where offshore wind farms are planned are concerned about potential impact on the value of their properties and losses to their investments.

Why offshore?
The consistent speed and dependability of coastal wind are just two reasons for the growth in offshore wind projects.

Like solar and other forms of non-polluting renewable energy, offshore wind harnesses the strength of nature. The force of wind rotates large propellers, which, through connected gearboxes, rotate high-speed shafts at over 1,500 revolutions per minute.

These feed into generators which convert this kinetic energy into electricity that flows from the towers through converters, transformers, substations, and on to homes and businesses through distribution networks.

Research has demonstrated differences in output and efficiencies between wind farms on land, and those constructed offshore. Onshore winds (from the sea onto land) are consistently stronger than winds on land, due to the lack of physical barriers at sea, and that when warm air over land rises, cooler air over the sea quickly moves to fill the space.

And according to the American Geosciences Institute, even slight increases in wind speed result in significant energy production increases, with turbines in winds of 15 miles per hour capable of generating twice as much energy as turbines operating in slightly slower 12 mph winds.

Unlike oil, gas, and coal, offshore wind and solar sites do not consume large quantities of water, nor do they generate greenhouse gas emissions (GHGs) or polluting environmental waste.

The cons of offshore energy
Objections from residents and businesses to the impact on property values of offshore solar and wind projects are common in coastal areas. The fishing and seafood industry too, frequently voices its misgivings about proposed offshore energy sites and their effect on the environment, namely fish and other ocean dwellers.

Some of the reasons for the success of offshore wind farms can also work against them, with powerful winds and waves causing costly damage to energy installations both above and below the water, including to power cables on sea beds.

Part of the challenge of tapping into offshore wind involves erection of the turbines themselves. With today’s technology, construction of fixed-foundation wind turbines in waters exceeding 200 feet (60 meters) is more complex than land-based wind farms, and remains difficult.

To negate this problem, some other types of wind turbines are built on floating platforms, which have the advantage of being moorable in deeper waters far from shore.

Late bloomer
The United States is relatively backward in developing offshore wind and solar projects, far outpaced by Germany, Denmark, Belgium, Holland, and the United Kingdom, which has the greatest installed capacity in all of Europe. With rising electrical costs, the closure of coal plants across the U.S. and the push towards greener forms of energy, America will undoubtedly see many more coastal wind projects in the coming years.

One of offshore winds’ best allies in the energy stakes is another form of green energy, namely solar. Recent studies demonstrate that large-scale solar-wind hybrid projects offshore generate power more efficiently than wind alone, and are easier to build than photovoltaic (PV) solar units alone.

A reason behind the merging of wind and solar is nature itself. Sun and wind follow their own schedules and don’t always appear over the sea at useful times, so a technology with two strings to its bow that’s able to take advantage of either form of renewable energy separately is at an advantage.

Scientists at Utrecht University in The Netherlands – one of the leaders in the solar-wind hybrid sector – recently conducted a feasibility study of a “floating solar installation,” part of a new 752 Megawatt (MW) North Sea wind farm. This resulted in a paper, Pooling the cable: A techno-economic feasibility study of integrating offshore floating photovoltaic solar technology within an offshore wind park.

Among the findings, authors of the paper say that integrating solar to offshore wind parks is an option to increase output, while sharing the costs of construction and maintenance, “leading to overall decreased capital and operational expenditures.” They add, “We have calculated optimal wind and solar combined capacity given meteorological conditions in the North Sea, showing that curtailment of solar is quite limited.”

Worldwide, other countries are also investigating the marriage between offshore wind and solar. A recent study from Ireland states that the combination could stabilize prices over the long haul.

Yet another recent report from Norway’s DNV GL, an international registrar / classification society, comments that the North Sea may be home to about 100 MW of floating solar capacity by 2030, jumping to 500 MW by 2035.

They describe the offshore wind industry as “booming.” Indeed, major players are onboard with the development of this technology, including GE Renewable Energy.

With GE active in areas including hydro power, grid solutions, and onshore wind, offshore represents yet another step towards renewable power for the energy juggernaut. It makes perfect sense. With increases in offshore wind energy from 17 Gigawatts (GW) to 90 GW projected for the coming decade, experts believe offshore wind power will be responsible for 15 percent of the world’s wind industry.

Biggest ever
Acknowledging the potential of offshore wind, GE has invested over $400 million in Haliade-X. Announced in March 2018, Haliade-X remains the most powerful offshore wind turbine to date.

With a 12 MW direct drive generator, the 260 meter tall turbine it will produce 45 percent more energy than any other offshore wind turbine in existence. Its blades measure 351 feet (107) meters in length – longer than a soccer field – and just one of the Haliade-X 12 MW turbines can generate about 67 GWh annually.

This is “enough clean power for up to 16,000 households per turbine, and up to one million European households in a 750 MW windfarm configuration,” according to GE.

The sheer power-generating capacity of Haliade-X would he been unthinkable just a few years ago. Like other wind projects, it will take advantage of stronger, more regular winds far away from shore.

And while the future of offshore wind farms remains assured, what does remain to be seen is how an acceptable balance between these huge projects’ value to society and their impact on the oceans and fisheries can be found.



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