Mother Nature’s Icelandic lava show has been an impressive reminder that we are surrounded in every direction by awesome amounts of energy. Photons shower down, water cascades, wind blows while waves pulse and tides flow. And the Earth beneath our feet stores heat from the sun’s rays above while generating its own from dark sources below.

Icelanders tap their volcanic endowments for heat and power. The country is one of a handful already providing 100 per cent clean power, while 90 per cent of its homes are heated with geothermal energy and electric vehicles are fast approaching half of all new sales. You can even rent one from a company called Lava Car Rental.

Volcanism has its downsides — just ask the Icelanders forced to evacuate recently to escape the lava flows. Thankfully, tamer versions of geothermal energy are available and they’re heating up the world of climate tech.

Confusingly, all of them are referred to as “geothermal” even though they are totally different approaches to energy, other than the use of underground pipes.

You’ve probably heard of private developers or campuses tapping heat at relatively shallow depths where the ground holds the sun’s warmth all year round. No flirting with lava or drilling deep to hot rocks. Just bore some holes or tap into a water source, run some pipes, fill them with fluid, tack on a heat pump and you’ve got heat. Crucially for our climate-changing world, you’ve also got cooling.

They’re technically called “ground source” heat pumps, sometimes “geothermal heat pumps” or “geoexchange systems.” Occasionally even “earth-coupled” (delightful and vaguely titillating — that would have my vote but seems unlikely to win the broader naming competition).

They work. In fact, they’ve been around since the 1950s. No more burning gas in homes and heat pumps are beyond efficient — ground-source heat pumps give back four to five units of energy for every one you put in. "The closest thing to a silver bullet" in the race to clean energy, says the head of the International Energy Agency.

And … they’re very expensive to install on your own.

But very smart people are rolling them out under whole neighbourhoods in a version of district heating known as a geothermal network, where a few boreholes supply a community, distributing the system cost while providing heating and air conditioning to multiple buildings. In New England, studies show networked geothermal to be cheaper than gas or air-source heat pumps and scalable across the region.

In Massachusetts, the gas company even got on board. National Grid and Eversource are regional utilities installing the first geothermal networks. There’s a real logic for the utilities. After all, the system looks a lot like what the gas utilities have been doing all along — a network of buried pipes serving neighbourhoods — replicating the gas network but without the gas. Instead of fighting decarbonization, it’s a chance for the gas company to embrace clean energy, transform itself and avoid a death spiral.

To its credit, National Grid was already moving on trial projects before the State of Massachusetts mandated a move away from gas. New York and Colorado have also passed laws requiring gas utilities to build geothermal networks.

Geothermal networks are one of those........

© National Observer