Oil and gas companies are turning to renewable gas, green hydrogen and biofuel as a pathway to cutting emissions in the transportation and building sectors while retaining existing infrastructure.
But deep energy efficiency retrofits coupled with building electrification via heat pump and induction cooktops is the central solution to decarbonizing buildings, said Ben Butterworth, senior manager of climate and energy analysis at the Acadia Center. He spoke at the Northeast Energy and Commerce Association’s (NECA) Fuels Conference on Sept. 22.
The conference brought together policy experts from stakeholder organizations, such as Acadia, oil and gas companies Enbridge and Shell Oil, and utilities Eversource and National Grid, to discuss the benefits and challenges of green hydrogen.
Zeyneb Magavi, co-executive director of the Home Energy Efficiency Team (HEET), presented the alternative of using geothermal heat pump networks for clean home heating and cooling.
Following is some of what we overheard at the event.
New England utilities, such as Eversource and National Grid, are in the process of approving and siting locations to test HEET’s geothermal energy technology. Companies such as Enbridge and Shell Oil are investing in renewable natural gas or green hydrogen to reduce emissions while using existing natural gas infrastructure.
Green hydrogen is created by splitting water into hydrogen and oxygen in an electrolyser using electricity powered by renewable energy.
“It’s going to take multiple pathways to achieve decarbonization,” said Steve Elliott, director of business development for Enbridge. “I think we really need to consider leveraging the best attributes of molecule-based energy like gas.”
However, green hydrogen faces steep challenges, which inhibits a widescale rollout. There is a 20% to 40% energy loss in the electrolysis process and green hydrogen-based, low-temperature heating systems consume 500% to 600% more electricity than heat pumps, making it much less cost-effective, Butterworth said.
Pure hydrogen is a five times more potent greenhouse gas than carbon dioxide when it is released directly into the atmosphere via leaks, and it leaks out of pipes more easily than natural gas because the molecules are smaller, Butterworth said.
“We don’t have time for the green hydrogen economy to develop,” he said. “We need action now.”
As an alternative to hydrogen, Magavi’s GeoBlock concept, also known as a geothermal district, could use existing natural gas rights-of-way to heat and cool buildings. The GeoBlock is a system of networked ground-source heat pumps with a shared ambient temperature loop that delivers cooled or heated water to customer buildings. A heat pump in the building pulls heating or cooling off the supply loop, and geothermal boreholes in the right-of-way maintain the temperature of the system.
“If we are going to meet our emissions mandates, and do it without raising customer bills,” the GeoBlock is a solution that is “ready to do that now,” she said.
Thermal energy can be deposited in bedrock for storage and removed, in part, a year later, helping to make geothermal energy distribution systems highly cost-effective, Magavi said. European installations of similar shared loop systems without boreholes report 30% to 40% energy savings because they allow the utility to move excess or waste thermal energy across space and reuse it, according to HEET.
Adding boreholes to the shared loop allows the utility to store excess or waste thermal energy for reuse, whether it’s wind energy at night that is used the next day or heat in the summer used the next winter.
“If installed by a utility and amortized over time as gas pipes are, the GeoBlock is projected to deliver heating at a lower cost than gas,” Magavi said.