What is geothermal, anyway???

Deep within the Earth is a hot, molten iron core. As you get closer to the surface, the temperatures moderate until you reach the surface air temperature. If there are cracks, hot springs or volcanoes bringing fluids to the surface, you can use that to heat or run a turbine and create power. Otherwise, you can drill down 10 feet or more and get to a zone with a constant 54 degree temperature. You can use that constancy to heat and cool your home, office or other buildings.

How do we get from underground temps to cozy buildings?

Because it’s expensive to drill deep, projects often use shallow horizontal pipes, not much deeper than 10 feet down, to reduce costs

You have to drill underground, set some water pipes in place, then bring the loops of water up through a heat pump. The heat pump can cool your building in the summer months and warm it in the winter.

Horizontal or vertical? A feasibility study would tell us which arrangements would be best for which locations.

Projects use deep, vertical pipes if there is not enough area for cooling or heat with a horizontal design, especially large buildings on small lots or high-rise units

Geoexchange – moving energy back and forth from ground heat to a comfy home or business …

Source: Geo Power Book

Compared to other technologies, geoexchange is much more efficient, with minimal carbon footprint

Conventional HVAC systems move 70-98 units of energy for every 100 taken in, wasting 2-30 units of energy in the process.

A geoexchange system moves 300-600 units of energy for every 100 units of power used – no waste, in fact you get a net gain of 3-6 times the energy used! And if those 100 units of power are solar- or wind-generated, the carbon footprint is nominal.

And if you network the buildings, it gets even better …

◦ Achieve economies of scale in drilling, digging, installation        So – it costs less!

◦ Energy not needed in one home or building is available to others       So – it costs less!

◦ Energy not needed by any building is stored in the ground for later       So – it costs less!

◦ Unused heat in summer is stored in the ground for use in winter       So – it costs less!

◦ A large project could be done cooperatively with the City, PGW and others        So – it costs less!

Image courtesy of HEET.org

So that’s our vision

  • ground-source heat-pumps for geoexchange wherever feasible,
  • networking them together where possible,
  • the project done with PGW as the managing partner if we can achieve agreement

All in order to become more sustainable, bring about more climate justice and help Philadelphia achieve its climate goals.

Do you want to know more about geothermal? We offer more detail here.