A constellation of 5,400 offshore wind turbines meet a growing portion of Europe’s energy needs. The United States has exactly seven.

With more than 90,000 miles of coastline, the country has plenty of places to plunk down turbines. But legal, environmental and economic obstacles and even vanity have stood in the way.

President Biden wants to catch up fast — in fact, his targets for reducing greenhouse gas emissions depend on that happening. Yet problems abound, including a shortage of boats big enough to haul the huge equipment to sea, fishermen worried about their livelihoods and wealthy people who fear that the turbines will mar the pristine views from their waterfront mansions. There’s even a century-old, politically fraught federal law, known as the Jones Act, that blocks wind farm developers from using American ports to launch foreign construction vessels.

Offshore turbines are useful because the wind tends to blow stronger and more steadily at sea than onshore. The turbines can be placed far enough out that they aren’t visible from land but still close enough to cities and suburbs that they do not require hundreds of miles of expensive transmission lines.

approved a project near Martha’s Vineyard that languished during the Trump administration and in May announced support for large wind farms off California’s coast. The $2 trillion infrastructure plan that Mr. Biden proposed in March would also increase incentives for renewable energy.

The cost of offshore wind turbines has fallen about 80 percent over the last two decades, to as low as $50 a megawatt-hour. While more expensive per unit of energy than solar and wind farms on land, offshore turbines often make economic sense because of lower transmission costs.

“Solar in the East is a little bit more challenging than in the desert West,” said Robert M. Blue, the chairman and chief executive of Dominion Energy, a big utility company that is working on a wind farm with nearly 200 turbines off the coast of Virginia. “We’ve set a net-zero goal for our company by 2050. This project is essential to hitting those goals.”

rely on European components, suppliers and ships for years.

Installing giant offshore wind turbines — the largest one, made by General Electric, is 853 feet high — is difficult work. Ships with cranes that can lift more than a thousand tons haul large components out to sea. At their destinations, legs are lowered into the water to raise the ships and make them stationary while they work. Only a few ships can handle the biggest components, and that’s a big problem for the United States.

A 1,600-mile round trip to Canada.

Government Accountability Office report published in December. That is far too small for the giant components that Mr. Eley’s team was working with.

So Dominion hired three European ships and operated them out of the Port of Halifax in Nova Scotia. One of them, the Vole au Vent from Luxembourg, is 459 feet (140 meters) long and can lift 1,654 tons.

Mr. Eley’s crew waited weeks at a time for the European ships to travel more than 800 miles each way to port. The installations took a year. In Europe, it would have been completed in a few weeks. “It was definitely a challenge,” he said.

The U.S. shipping industry has not invested in the vessels needed to carry large wind equipment because there have been so few projects here. The first five offshore turbines were installed in 2016 near Block Island, R.I. Dominion’s two turbines were installed last year.

Had the Jones Act not existed — it was enacted after World War I to ensure that the country had ships and crews to mobilize during war and emergencies — Dominion could have run European vessels out of Virginia’s ports. The law is sacrosanct in Congress, and labor unions and other supporters argue that repealing it would eliminate thousands of jobs at shipyards and on boats, leaving the United States reliant on foreign companies.

Demand for large ships could grow significantly over the next decade because the United States, Europe and China have ambitious offshore wind goals. Just eight ships in the world can transport the largest turbine parts, according to Dominion.