Long Island can meet 100 percent of its electricity needs — yes, 100 percent — within two decades with safe, clean, renewable energy.

That’s the conclusion of an important new study by Synapse Energy Economics, a consulting firm out of Cambridge, Massachusetts long involved in energy research for utilities, governments and others.

The study, titled “A Clean Electricity Vision for Long Island,” places Long Island “at a crossroads,” says Gordian Raacke, executive director of East Hampton-based Renewable Energy Long Island, which commissioned it. Funding came from the Rauch Foundation and the Long Island Community Foundation.

The study concludes that it is “technically feasible for Long Island to have a 100-percent renewable and zero-carbon electricity supply by 2030.” The power would come from technologies all now commercially available: solar, through widespread installation of rooftop panels; wind, with an emphasis on offshore wind turbines; and hydropower. Energy efficiency would also be stressed.

“We now have everything we need to make the transition from dirty and dangerous fossil fuels to a clean and renewable energy supply,” commented Mr. Raacke. “This transformation of our energy supply is now both achievable and affordable and presents a tremendous opportunity and challenge to all of us — Governor Cuomo, elected officials, our utility, municipalities, the private sector and every Long Islander.”

“LIPA and state leaders have verbally supported renewable energy for a decade,” notes Adrienne Esposito, director of Citizens Campaign for the Environment. “Now is the time to put those words into action … Large-scale renewables need to be a real part of our energy generation and this study shows we can do that. Now, we need the governor to make it happen.”

Not only would there be the benefits of electricity independence for Long Island but, adds the study: “An aggressive move to renewable energy would provide benefits that are not addressed here, including local economic development, reduced fuel price risk and reduced environmental and health impacts of power generation.”

What the study envisions isn’t unique. “Cities and states worldwide,” it notes, “have established aggressive renewable energy targets.” These include San Francisco, which plans to have 100 percent of its electricity provided by renewable energy by 2020; Scotland, which plans to get all its electricity from renewable by 2020; and Denmark, which intends to have 100 percent of its electricity and heat coming from renewables by 2034.

Well-documented in the study is the fact that safe, clean — and cost-competitive — renewable energy technologies are here today and can provide all the power we need.

“Former Governor Mario Cuomo stood with Long Island safe energy activists to close the Shoreham nuclear plant,” comments Peter Maniscalco, educator and former coordinator of the Stop Shoreham Campaign. Now, says Mr. Maniscalco, the way is clear for Governor Andrew Cuomo, his son, as he “seeks reorganization” of the Long Island Power Authority, “to create a renewable energy era on Long Island — 100 percent Renewables Now!”

The challenge in having this happen involves political will and the strength to reject dirty, dangerous energy sources and those with vested interests in them (and those who believe them).

For example, Synapse last year did a study, commissioned by Riverkeeper and the Natural Resources Defense Council, on the energy consequences of closing down the two old and accident-plagued Indian Point nuclear power plants 24 miles north of Manhattan. It concluded that there is “ample existing and new [energy] resources available” to replace the Indian Point electricity. The Indian Point plants are unnecessary. Other studies have come to the same conclusion. But that hasn’t stopped the long pro-nuclear newspaper Newsday, for example, from bemoaning an Indian Point shutdown.

Likewise, we can anticipate the business-as-usual forces involved with the dirty and dangerous energy technologies to ignore the Long Island Synapse study. “We need LIPA to stand up for the health and future of Long Island by taking bold steps to make large-scale renewable energy a reality,” says Lisa Dix, a campaigner for the Sierra Club. “This report shows that a clean energy future is possible for Long Island, so now we need LIPA to make it happen.”

Indeed, LIPA does need to make it happen—and a challenge of our time is to make the vision a reality. It will probably only happen if people demand it.