National Grid, one of the largest investor-owned utility companies in the world, unveiled a plan last month to wean New York off natural gas by 2050.

The process would call for the utility to slowly transition to renewable natural gas, also known as biogas and biomethane. It’s essentially the gas captured when methane is released from landfills, farms and wastewater treatment plants. Those emissions can be collected and purified and then used in pipelines to provide gas for fuel, heat, hot water and cooking.

Biogas is touted as an environmental-friendly alternative to replace the conventional use of liquid natural gas in pipelines because these recurring emissions from waste streams would otherwise contribute to further greenhouse gas releases.

National Grid’s climate strategy does include electrification with wind and solar power as part of the transition. The company plans to “decarbonize” natural gas with a mixture of biomethane and green hydrogen. Its green hydrogen would be produced through the electrolysis of water. An electric current — produced by renewable energy such as solar and wind — splits water, separating out oxygen as a byproduct and leaving the hydrogen for part of the company’s fuel.

“We're going to rely on a lot of solar, wind and storage, energy efficiencies — [it’s] just foundational,” said Donald Chahbazpour, director of policy and regulatory strategy for National Grid.

But gas will continue to flow, and environmental experts say that the plan is not a solution that will help reduce global warming because the process still produces carbon emissions.

Chemically, renewable natural gas is the same as the liquid natural gas presently flowing into buildings. The renewable form would also be delivered through the same pipelines that are highly prone to leaking methane into the atmosphere. When combusted, both gasses also produce a similar amount of carbon emissions.

“I see it as possibly filling in a small piece of the puzzle to reduce carbon intensity out in a relatively inexpensive way,” said Ken Gillingham, an economics professor at the Yale School of the Environment. “But that's not going to solve the climate crisis. The heavy lifting and replacing fossil natural gas is going to have to come from electrifying, at least a high percentage of end uses that are currently using natural gas.”

What is renewable natural gas?

New York City’s more than 1 million buildings create over 70% of its greenhouse gas emissions, and approximately 40% of that is directly caused by the use of fossil fuels for heating water and indoor spaces. Replacing liquid natural gas is intrinsic to reducing the impacts of climate change – and a requirement under state laws.

By 2050, the mixture running through National Grid’s existing pipelines will be 80% biogas and 20% green hydrogen, by volume. But the company’s projections show it would still be reliant on liquid natural gas for at least 18 more years. The intermediate composition of gas delivered to homes by 2040 will gradually become 20% green hydrogen, 30% biogas and the remaining half will be liquid natural gas and hydrogen clusters

Currently, the gas utility giant is trying to scale up production of green hydrogen and biomethane through pilot projects. But getting to 80% biogas is no simple task.

National Grid's clean energy vision

National Grid's clean energy vision

National Grid's clean energy vision
National Grd

The four main sources for biomethane are landfills, wastewater, food waste and livestock manure from farms. When gas is captured from these sources, it’s 60% methane and 40% carbon dioxide.

But that can’t be readily injected into pipelines to heat homes. First, it must be purified to 98% methane by removing the carbon dioxide. Infrastructure will need to be built for purification facilities, and some additional pipeline may be constructed to take that renewable natural gas and bridge it to the existing network.

One such site that is being prepped for this purpose is the Newtown Creek wastewater treatment plant in Brooklyn. Because it is already located in an area of an existing pipeline, National Grid said it will be simple to connect it to the current system.

Will renewable natural gas reduce carbon emissions?

According to the U.S. Energy Information Administration, a single resident uses about 68 million BTU (British Thermal Units) of natural gas per year in New York State. Retrofitting landfills for the purpose of making renewable natural gas can cost between $6-10 per million BTU — or up to $680 to cover a single year of gas for a New Yorker. For food waste and manure facilities, that price can reach $20 per million BTU — or $200 for the annual gas consumption per capita in New York.

But less than half of renewable natural gas projects can be created at this cost, according to the American Gas Foundation, an energy trade group. In regions where long distances separate pipelines and renewable natural gas sources, purification facilities will cost more than $20 per million BTU. Compare that against current liquid natural gas prices, which can be developed at a cost less than $4 per million BTU.

So, transitioning to renewable natural gas could lead to increased energy prices for customers, if those costs aren’t otherwise absorbed. Another added expense comes from the green hydrogen. This fuel would also require upgrades to existing pipelines and infrastructure.

Scaling up production of renewable natural gas won’t be so easy, according to Gillingham, because there is limited capacity to expand, and there isn’t enough to match the current demand for liquid natural gas. Expanding production would require creating farms or landfills to make manure or decompose organic materials like food products.

Excerpt from National Grid's vision for a fossil-free future

Excerpt from National Grid's vision for a fossil-free future

Excerpt from National Grid's vision for a fossil-free future
National Grid

“Relative to the amount of natural gas that we use, this is just not going to replace natural gas,” Gillingham said. “The potential scale is much larger for the other renewables. For solar, you could power the entire country if you cover the state of Connecticut with solar panels.”

But the Empire State is still heavily dependent on fossil fuels, and according to National Grid, its gas network delivers three to four times more energy on its peak day than an electric system. In the New York metro area, nearly 70% of energy comes from fossil fuels.

Even with full electrification, National Grid contends that a reliable power system will need liquid natural gas or its alternative renewable natural gas on peak cold days when the sun isn’t shining and the wind isn’t blowing to continue delivering energy consistently. And removing gas hookups and electrifying a home can be expensive, more than $25,000 per household.

“When you really sharpen your pen and do the analysis, you also begin to see that there is no silver bullet,” said Chahbazpour from National Grid. “You need every tool in the toolkit, including some of these things” like biomethane.

Increasing demand for biogas could also motivate farms and landfills to grow in size, and those facilities are already substantial sources of greenhouse gasses. The California Climate and Agriculture Network (CalCAN), a network of sustainable agriculture advocates, reports that upping the production of manure and decaying food waste could also increase the impacts on the local environment because methane is more potent at warming the atmosphere than carbon.

“Methane burning is a lot better [than liquid natural gas], but it's still not great for the climate,” Gillngham said.

Given the emissions, the added expense and the infrastructure required to upgrade energy systems to replace liquid natural gas with renewable natural gas, experts like Gillingham don’t see biomethane as a comprehensive solution.

But it could be useful on days when the wind doesn’t blow to turn offshore turbines and the sun doesn’t shine bright enough for solar power. They see it as a back up to full electrification powered by typical renewable sources, and not a substitute for the large amount of liquid natural gas currently in use.

“We need to get off gas anyway, and it's going to be less expensive and easier to just electrify,” Gillingham said.