Energy company National Grid is trying to expand its Greenpoint natural gas compression facility in Brooklyn, but New York’s Department of Environmental Conservation (DEC) has again delayed making a final decision on whether to approve it. The DEC wants the state Public Service Commission (PSC) to first determine whether the expansion is necessary for reliability of the City’s energy supply.

That question of reliability is ignored by opponents of the facility, who not only want to stop its expansion, but shut it down completely. They argue that the proposed expansion conflicts with the goals of New York’s Climate Leadership and Community Protection Act (CLCPA). That law requires the state to achieve an 85 percent reduction in greenhouse gas emissions by 2050 and achieve 100 percent zero-emissions electricity production by 2040, only 18 years from now.

From that perspective, opposition to expanding the facility is understandable. Opponents also are concerned about the health effects of the facility’s emissions on residents of the area. That’s understandable, too.

But reliability of the electricity supply is also a critical concern. When the power goes out during a heat wave or cold snap, people die, and it’s mostly the poor and elderly.

New York City hopes to replace its heavy reliance on natural gas and oil with wind power, both onshore  and offshore, and hydropower from Quebec. The irony is that its current reliance on natural gas and oil – and the resulting greenhouse gas emissions – is in part a consequence of the premature shutdown of the emissions-free Indian Point Nuclear Facility.

The question for the future, though, given the closure of Indian Point, is how New York ensures a reliable electrical supply. And as much as hydro and wind are desirable from an emissions perspective, they do not provide that reliability.

The combination of wind power and Quebec hydropower may provide enough electricity – or nearly so – most of the time. But if there is any time at all when it does not, then backup power is needed.

Windpower is an intermittent resource, meaning it is not reliably available on demand. Put simply, there are times when the wind fails to blow. And New York is not a large enough area that we can be sure the wind will always be blowing somewhere.

Meanwhile, Quebec hydropower may not be available when it’s needed most, during a bitter winter cold snap. This is because any severe winter weather system covering New York is also likely to have enveloped Quebec as well, and increased demand for electricity there will take precedence over meeting New York City’s needs. In addition, Quebec has its own plans for reducing carbon emissions, which will increase demand on its hydroelectric power supply.

In plain English, there will be times when a reliable backup source of electricity for New York City will be needed. If it’s not natural gas, what will it be? That’s a life-or-death question with which opponents of the Greenpoint facility have not seriously grappled.

But grappling seriously with such questions is the PSC’s job. And the CLCPA allows for the building and expansion of natural gas facilities if necessary to ensure reliability.

We have already seen the DEC deny permits for two facilities that would have helped ensure electric reliability. These cases will become increasingly important as New York tries to reconcile the goals of the CLCPA with the need for a reliable supply of electricity.

Given that this project has been delayed multiple times, the PSC should act as quickly as it can on the DEC’s request. If the expansion is indeed necessary to maintain reliability – to prevent power blackouts and the resulting economic damage and loss of life in New York City – the PSC should determine so quickly and then the DEC should issue the necessary permits.