GEOTHERMAL TECH
DEEP HEAT
GEOTHERMAL HEAT IS BEING HARNESSED TO HELP PLANTS AT THE EDEN PROJECT GROW. ADVANCED NEW TECHNOLOGY COULD TURN IT INTO A RENEWABLE SOURCE OF CLEAN, GREEN ENERGY FOR EVERYONE
by JHENI OSMAN
The Eden Project in Cornwall, southwest England, is home to the world’s largest indoor rainforest
EDEN PROJECT
Giant domes, made from what looks like vast sheets of bubble wrap, nestle in a peaceful valley in Cornwall, UK. The domes contain plants from all over the world and form the signature feature of the Eden Project.
Next door to the Eden Project, on a parcel of paved land roughly the size of a football pitch, sit a couple of innocuous-looking 10m-long (32ft) storage containers and a 3m-high (almost 10ft) red metal structure. Directly beneath this structure, is a small hole that drops 5.3km (over 3 miles) down into Earth’s crust. With a diameter of only 25cm (the width of a pizza), it’s just wide enough to house two pipes; one wider, outer pipe through which to pump cold water down and an inner, ‘core’ pipe through which hot water is pumped back up to the surface. From there it’s used to heat the Eden Project, maintaining the tropical temperatures the plants inside its domes need.
Today, a range of geothermal energy systems, like this one, make use of the natural heat stored deep below Earth’s surface, either for heating homes, commercial facilities or buildings like those at the Eden Project, or for generating electricity.
You can generate electricity with geothermal energy in two ways: either by pumping hot water and/or steam from underground wells up to the surface to drive a turbine; or by a process known as ‘hydrofracturing’, which forces cold water into hot rocks deep underground that heat the water before it’s returned to the surface to power a turbine. “The deeper you go, the hotter it gets,” says Augusta Grand, CEO of Eden Geothermal. “The centre of Earth is as hot as the surface of the Sun. Geothermal is like the sleeping giant of renewables – it has so much potential.”
Augusta Grand was the head of policy at the Eden Project before becoming the chief executive officer of Eden Geothermal in 2019
It seems that giant might be waking up. Quietly, around the world, a handful of engineering start-ups have been digging deep in the hopes of harnessing geothermal energy to produce electricity – the kind you can plug into a national grid and send to homes. If they’re successful, it could completely change how the world creates its energy: they just have to find the right kind of rocks…
GETTING INTO THE BASEMENT
Generating electricity requires rocks with much higher temperatures than those used for the Eden Project’s “relatively simple” heating system. Historically, access to extreme temperatures was limited to volcanic regions, such as Iceland and Italy. But now, game-changing technology means that new, ultra-deep geothermal projects are looking to drill many