When we say the wind blows, we’re actually referring to the currents of a vast and powerful ocean of air. Unlike its watery counterpart, however, wind can be found—and thus harnessed—everywhere across the Earth’s surface. In the specific language of the wind power industry, it’s found both on and offshore.
On Drawdown’s list of top 100 strategies for climate change, onshore wind turbines rank second[i], which the potential to reduce CO2 emissions by nearly 85 gigatons by 2050. Offshore wind turbines, however, come in 20 spots later at #22[ii], reducing emissions by only 14 gigatons[iii] in the same time frame. This major discrepancy exists despite the fact that, offshore, the wind blows longer and stronger[iv]. What gives?
Put simply, the very things that make offshore wind a more powerful renewable energy than its land-based counterpart also make it more technologically challenging[v]—and therefore more expensive—to harness. Offshore turbines must be far sturdier than those on land to handle such powerful air. They must also be taller to reach up out of the seabed. Giant cables are needed to bring the electricity harnessed back to homes and businesses on land. Coordinating supply chains in the ocean requires more complex logistics.
Nevertheless, offshore wind is growing. While the Block Island offshore wind farm in Rhode Island, completed in 2016, is the only facility of its kind[vi] operating in the U.S., many states along the Eastern seaboard have set offshore wind targets and inked deals with companies.
New Jersey, for instance, just announced the Ocean Wind Project[vii], a partnership between its own PSEG and the Danish energy company Ørsted to build a 1,100 megawatt (MW) facility[viii] 15 miles off the coast of Atlantic City. New York State, in turn, has pledged[ix] to get 9,000MW of its energy from offshore wind by 2035 and just awarded[x] two contracts to build farms with 1,700MW capacity off of Long Island in July 2019.
The U.S. has a long way to go before it catches up to Europe’s current offshore generation of 18,5000MW per year[xi] (and growing), but states are leading the way to capture the wind off the water and bring it back on land to power our homes and businesses, cities and towns, factories and farms. Let’s take a closer look at the present and future of offshore wind power.
Why and Wherefore Offshore?
We’ve already noted that wind blows stronger and more consistently offshore, primarily because so few geological or manmade objects like mountains or skyscrapers are in the way to slow it down. Strength matters, since a small increase in wind speed equals a large increase in electricity generated; for example, a turbine can produce twice as much electricity[xii] with a 15mph wind than with a 12mph one. Moreover, offshore wind—unlike onshore—is actually stronger during the daytime[xiii], peak hours for electricity use.
The National Renewable Energy Laboratory estimates that more than 2,000 gigawatts[xiv] (or 2 million MW) of electricity could be harnessed off the U.S.’s coastlines. For comparison: the Hoover Dam generates 2 GW[xv] of power each year, enough to power 350,000 homes.
More importantly, now that technology is starting to catch up to the specific challenges of harnessing our offshore winds, we’re seeing that promises of cheaper and greener electricity through offshore wind are more than just hot air.
Cost has been the major setback when it comes to offshore wind; companies simply weren’t willing to pay the hefty upfront costs of installing expensive technology. However, advances in turbine technology have grown exponentially[xvi] in just the last 15 years, resulting in bigger and stronger turbines able to keep pace with the strength of offshore wind.
Just one example: by 2021[xvii], GE will have installed its newest turbines off Europe; with 220m (722ft) wingspans, just one can power 16,000 homes. These turbines are also more resilient—able to resist saltwater corrosion and strong winds far better than previous models.
One unique challenge for offshore wind in the U.S. has been the depth at which these farms would need to be installed, since more than 60%[xviii] of our available offshore resources are located in waters deeper than 200ft. An ingenious solution has only recently become scalable: floating platforms[xix].
Early signs show that these engineering marvels are the wave of the future; after only 3 months of operation, the world’s first floating offshore farm[xx] off the coast of Scotland reported 65% capacity[xxi]. That’s better than onshore farms (37% capacity[xxii] in the U.S. in 2018) and even conventional thermal power plants (54-55%[xxiii]). Higher capacity factors also mean lower prices; Statoil, the Norwegian company behind the Hywind plant, believes it can be competitive with thermal power[xxiv] by 2030.
Prices can be even lower for more conventional (that is, non-floating) offshore turbines. Vineyard Wind[xxv] signed a contract with the state of Massachusetts in April 2019 to provide electricity at 8.9 cents per kilowatt-hour[xxvi], two-thirds less than other renewables.
In fact, the only reason why fossil fuels remain cheaper is the trillions of dollars the industry receives in subsidies each year worldwide; in 2015, that amount equalled $10 million USD per minute[xxvii]. If you want to see offshore wind power come to your town or city, consider taking up the fight against fossil fuel subsidies[xxviii] while you advocate for wind power.
The development of offshore wind power may be in its infancy compared to its onshore counterpart, but its potential is as vast and powerful as the ocean of air itself. We must seize this opportunity.
[iii] Drawdown, 4.
[xxvii] Drawdown, 3.