How it works and what you need.
A geothermal heat pump works on the principle of a compressed gas
getting hot. When we take the heat out of the gas, the gas condenses
into a liquid. That liquid has to be evaporated back into a gas before
it can be compressed again to produce heat.
An open loop system works on a water supply being pumped to the unit.
Once the heat has been obtained and has produced the hot water and heat
for the house, the water is then ‘dumped’ back in to the natural water
course via storm drains and soakaways or directly discharged back into
a leaching pond or ditch.
The only difference between the water being
dumped and the water coming out of the ground is the water is a few degrees
cooler.
If we use closed loop systems to produce 25 kw of heat, we would have
to bury 1200 metres of pipe in the ground or drill a minimum of 4
boreholes, 100 metre deep. This system would deliver a maximum of 45°C and
have a COP (Co-efficiency of Performance) of 3.2. To install an open
loop system, as a general rule, we need 30 litres of water per minute
and this is delivered on average by a 40-60 metre deep 4in borehole.
Open loop systems are far more efficient.
The thormec thermal-earth units will run with the COP of 5 and reduce
the co2 emissions for the whole heating system from 18 tonnes per annum
for gas to 3 tonnes per annum with thermal-earth heat pumps. If the
thermal-earth units were run by wind turbines and solar power, the co2 emissions would
be 0.
