Paul and I have been having a debate around what sort of energy a heat pump produces. Does it sit in the ‘energy efficiency camp” and should be counted as efficient use of electricity or does it lean towards Renewable Energy generation and should be counted as generating energy. Paul and I agreed after some thinking that it was ‘efficiency’ as the ‘fuel’ (electricity) for the system was being used efficiently. A heat pump was up to 300% more efficient than a normal electrical heater using its fuel (grid electricity) (you input one unit of electricity into a convector heater and it produces 1 unit of heat for example but you get up to 3 times more heat from a heat pump” ergo more efficient”I was happy”…but something was niggling and I had some time on Saturday morning and as I am a qualified GP (Google Practitioner) and so had a read. First of all what are the definitions of the two terms. I found theses which i was happy with
- “Energy efficiency is a measure of energy used for delivering a given service. Improving energy efficiency means getting more from the energy that we use.” DECC report
- “Renewable or infinite energy resources are sources of power that quickly replenish themselves and can be used again and again. BBC bitsize
I found plenty of evidence supporting both efficiency and renewable cases for a heat pump and some crackpot stuff as well. Lots of American articles call a ground source system geothermal which to my mind it is not. Most of the energy for the collector comes from the sun ultimately as it heat the surface ready to be harvested and not from the depths powered by volcanic activity (you can get these but they are different systems completely. (The Sun also heats the air, surface or water for heat pumps.. renewable?)
The problem is the electricity to power the heat pump which is mostly grid electricity and so is often not so renewable. But if you look at this electricity as auxiliary (making the thing work) and look at other renewables then it may be a different beast. Most renewable energy systems have an auxiliary need.For example the NT hydro on Snowdon produces approx 2,000,000 kWh pa annum. But it also has an auxiliary grid electrical supply when the hydro is off to keep the lights on, energize the main controller, open valves, open the jets and this can be around 8,000kw pa. Is the hydro a very efficient use of electricity or a renewable energy system? One electrical unit into the hydro basically produces two hundred and fifty units of electricity out?
If using this auxiliary energy view and that up to 3/4 of the energy for a heat pump comes ultimately from the sun I am now erring on the side of renewable energy from a heat pump as long as we take out the electrical bit from the overall heat produced. Efficiency is though the key. If the auxiliary energy from grid becomes more of the % then we would need to re-look at the argument. But I am open to a counter argument on this as I am still in my GP mode! (p.s. lets not get into f-gas in heat pumps and such like as there are some nasty metals and stuff in many renewable energy systems as well) Persuade me either way! I am still in receive mode! Ps either way it’s still a good heat source if designed and operated correctly!