New York State, which last month passed an ambitious law to reduce the emissions that cause climate change, said Thursday that it had reached an agreement for two large offshore wind projects.
The wind projects, to be built off the coast of Long Island, represent a big step forward for a technology that has been slow to take off in the United States because of local opposition and high costs. Experts have said offshore turbines, which are used extensively in Northern Europe, hold great promise because the wind tends to be stronger and more consistent offshore than on land.
Wind farms are a major energy source in the United States, providing about 7 percent of all electricity last year, up from about 2 percent in 2010. But almost all of those turbines are on land. By comparison, Britain expects to get 10 percent of its electricity from offshore wind next year, up from less than 1 percent in 2010.
The New York projects will start operation within the next five years and have the capacity to produce 1,700 megawatts of electricity, accounting for about 20 percent of Gov. Andrew Cuomo’s overall goal for offshore wind.
The wind projects, one of which will be 14 miles south of Jones Beach and the other 30 miles north of Montauk, are meant to be an important part of the state’s plan to get 70 percent of its electricity from renewable sources by 2030. The projects will be built by a division of Equinor, the Norwegian oil and gas company, and a joint venture between Orsted, a Danish company, and Eversource Energy, an American firm.
“With this agreement, New York will lead the way in developing the largest source of offshore wind power in the nation,” Mr. Cuomo said. “Today we are true to the New York legacy — to lead the way forward, to govern with vision and intelligence, to set a new standard and to match our words with action.”
Mr. Cuomo also signed a bill on Thursday that the Legislature passed last month requiring New York to eliminate net greenhouse gas emissions by 2050.
Developers of offshore wind farms have long struggled to win the support of Americans. Some projects foundered because electricity from offshore turbines generally costs a lot more than power from turbines on land. Politicians and coastal-property owners have also successfully opposed projects that they claimed would obstruct the picturesque views from East Coast shorelines.
Senator Edward M. Kennedy, the liberal Massachusetts Democrat, who died in 2009, famously opposed a proposed offshore wind installation near Cape Cod. Other elected officials, including President Trump, have also objected to wind farms. (Mr. Trump, who once called climate change a “hoax,” unsuccessfully opposed an offshore wind project near one of his golf courses in Scotland.)
Interest in offshore wind has been slowly growing in recent years as fears of climate change have mounted and technological advancements have reduced the cost of power from offshore turbines. Developers have also figured out ways to put turbines in deeper waters so that they are not visible from shore.
Still, there are just five commercial wind turbines in American waters, near Block Island, R.I. Several other projects are in development, including a small one under construction in Virginia by Dominion Energy. New Jersey last month selected Orsted to build a 1,100-megawatt wind farm off the coast of Atlantic City.
But some other projects, like Vineyard Wind’s plans for turbines near Martha’s Vineyard, have been delayed by federal and local officials.
The New York wind projects must still clear permitting and environmental hurdles. And the cost of the project will not be disclosed until after the agreements have been signed.
The state has set ambitious targets for renewable energy, but it received less than 5 percent of its electricity from wind and solar last year, according to the Energy Information Administration. New York faces numerous hurdles in increasing the use of renewable energy. In addition to finding space for more wind turbines and solar farms, it has to build more transmission lines — projects that invariably draw opposition from residents and others.
New York’s “enormous potential for clean energy production lies untapped, just off New York’s shores,” said Andrew Gohn, director of Eastern region state affairs at the American Wind Energy Association.
At the same time, the Trump administration has been seeking to roll back environmental regulations and make it harder for states to reduce emissions.
Other states, including California, are also looking closely at offshore wind. Lawmakers in California passed legislation last year requiring that 100 percent of the state’s electricity come from carbon-free sources by 2045.
But the deep waters off the West Coast will require wind turbines that can float, rather than be attached to the sea floor. The waters off the East Coast are shallower, making it easier and cheaper to install turbines there.
There are only slightly more than a dozen floating wind turbines around the world, mostly in Europe and Japan.
Some experts believe floating systems on the West Coast could eventually become a major energy source because the winds are even stronger and more consistent in the Pacific Ocean than in the Atlantic Ocean.
“These California projects could be the jumping-off point for what is far and away the largest offshore potential, and that is the Pacific Rim,” said Dan Reicher, a founding director of the Steyer-Taylor Center for Energy Policy and Finance at Stanford University. “It greatly dwarfs the East Coast. The floating systems are going to be really what we need to take advantage of the major wind resource globally.”