The Green Planet Monitor
Earth Heat, Salty Seas
Each year, fossil fuel burning sends 37 billion metric tons of CO2 into Earth’s atmosphere. A little over a tenth of those emissions – 4 billion tons – are associated with heating air and water in houses and buildings. So, clean ways to generate heat are in … hot demand.
Low power pumps transfer heat from air to water, and air to air.
Then there’s geothermal energy – piping hot water from beneath Earth’s surface, using it to heat buildings.
At the Technical University of Delft, in the Netherlands, two pipes are now being bored two and a half kilometers down. A ‘doublet’, this is called. Seventy-five-degree water filled with natural gas will be pumped up, the gas tapped, and the hot water used to heat campus buildings.
Slightly cooler now — 50 degrees – that water will be sent through a grid to surrounding homes, then pumped back down again.
Total output, once the system is up and running: eight megawatts of thermal energy.
There are about twenty geothermal doublets around the Netherlands today. That could expand to seventy-five by the end of this year, and up to 700 by 2050, at which point the Netherlands aims to be CO2 emissions-free.
The GPM spoke about the Delft Geothermal Project with Hemmo Abels. Abels is a geologist at the Technical University of Delft, in the Netherlands.
Listen to our conversation in today’s podcast. Click on the play button above, or go here.
On the other side of the ocean, in Canada’s largest city, Canada’s largest university is exploring another way to harvest the heat beneath our feet. Geoexchange, it’s called.
In a cavernous room beneath historic King’s College Circle, at the St. George campus of the University of Toronto, surface water is piped through a network of 370 boreholes, 250 meters down into warm limestone rock, then back up again.
In the winter, that subsurface water is used to heat campus buildings. In the summer, heat exchangers send surface heat back into the pipes, dispatching warmed water back down again, turning subsurface rock into a thermal battery, while cooling campus buildings.
But Canada’s largest urban geoexchange facility is more than just a low-emission heating and cooling system. It’s an educational display, and a bit of an art installation – an astounding maze of multi-coloured pipes for students, faculty and campus visitors to marvel at through glass windows, on their way to the campus’ underground parking garage (equipped with electric car chargers).
It’s also a subterranean classroom — a “mechanical engineering dream” students can study and be inspired by.
The GPM visited the U. of T.’s geoexchange facility, last November, buried beneath King’s College Circle. Scott Hendershot is Senior Manager of the Sustainability Office at the University of Toronto. Catherine Thorn is the U. of T.’s Director of Sustainability and Energy Management.
Listen to our conversation in today’s podcast. Click on the play button above, or go here.
Now, a totally different way to cut greenhouse gas emissions using water – fresh and salty water, to be specific.
Salinity gradient power, it’s called. Wherever fresh river water flows into salty seas, control that flow. Force fresh and salty water across ion selective membranes. Cations go one way, anions go another, set up electrodes on either end, you generate electricity.
That’s precisely what people have been doing in the Netherlands. In the middle of the long dike separating North Holland from Friesland – the Afsluitdijk, it’s called — fresh water from the inland Ijselmeer is combined with salt water from the North Sea.
REDstack is the first operating facility of this sort in the world. RED stands for ‘reverse electrodialysis’. Now paused, REDstack’s pilot plant has the capacity to produce one kilowatt of electricity.
Not much. But, scaling up will be easy. Having proved it works, under all conditions, the next step will be to build larger membrane stacks. A two megawatt demonstration facility could be up and running in a couple of years. The GPM spoke about salinity gradient power with REDStack co-founder and co-chair Pieter Hack.
Listen to our conversation in today’s podcast. Click on the play button above, or go here.
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