2024-08-17 23:14:33
There is a huge battery right under our feet. Absolutely stable, free to use and ripe for sustainable exploitation – unlike for example a flammable lithium-ion battery. Nothing more, nothing less than the Earth itself.
The ground is buzzing with geothermal energy that could heat or cool our homes – and now major US utilities are starting to take notice
While temperatures above ground fluctuate throughout the year, the ground remains at a constant temperature, meaning it has geothermal energy that engineers can tap into.
“Each building is located on a thermal capital”said Cameron Best, director of business development for Brightcore Energy in New York, which develops geothermal systems. “I really don’t think there is a more efficient or better way to heat and cool our homes.”
The US’s first networked geothermal neighborhood
And now the big utilities are starting to take a hard look at this system. A few months ago, Eversource Energy commissioned the US’s first utility-operated gridded geothermal neighborhood in Framingham, Massachusetts.
How it works
A heat pump in a geothermal system works in the same way as an air pump, except that instead of drawing heat from the air, the device draws it from water flowing underground.
Once the system is installed, buildings can draw heat from their foundations, rather than burning natural gas piped in remotely.
The pipelines pass through boreholes approximately 180-215 meters deep where the rock temperature is constant at 13C
A mixture of water and propylene glycol (a food additive that works in this case as an antifreeze) is piped into the pipes, absorbing geothermal energy, which is then channeled into 31 residences and five commercial buildings. Electric heat pumps use the liquid either for heating or cooling the space.
In the summer, the heat pump cools a space by transferring internal heat to the water, which is then pumped back into the earth. This helps warm the ground, recharging the underground battery so there is plenty of energy to export in the winter.
High efficiency
A gridded geothermal system is extremely efficient. It has a “coefficient of performance,” or Cop, of 6, meaning that for every one unit of energy that goes in, you get six units of heat out.
In contrast, natural gas furnaces have a Cop of less than 1.
If deployed across the country, such geothermal systems could go a long way toward decarbonizing buildings, which account for about a third of total U.S. greenhouse gas emissions.
“Each individual loop can be interconnected with other, neighboring ones, like Lego bricks, to keep growing,” said Audrey Schulman, executive director of the nonprofit climate solutions incubator HEETlabs
The start of something big?
The networks do not need special terrain morphology to operate, so they can be installed almost anywhere. The Framingham project could be the start of something big.
That goal may not be far off, as utilities face increasing pressure to phase out natural gas.
Eversource Energy and other utilities, representing 47% of US natural gas customers, have joined the Utility Networked Geothermal Collaborative. an intelligence sharing coalition.
“You’re asking yourself: are we a natural gas company or are we a thermal energy company?” said Holly Braun, manager of business development and innovation at Oregon utility NW Natural, which co-founded the coalition.
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