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Geothermal energy

PostPosted: Thu Sep 24, 2009 10:11 am
by Deni
Hi,

i know its not wind or solar but does anyone have any feedback on using of geothermal energy to heat and cool homes here in Aus plus boost hot water systems. As a renewable energy source it seems to be quite common in Europe and becoming so in America but not much used in Australia.

I am considering it for a new home and it would be good to have any info on energy consumption and performance.

cheers
Deni

Re: Geothermal energy

PostPosted: Thu Sep 24, 2009 10:13 am
by Deni
oh, and also if anyone knows if there are any rebates available for this renewable energy source.

Re: Geothermal energy

PostPosted: Thu Sep 24, 2009 11:13 am
by renew
Deni,

We have one or two distinct applications in geothermal. In WA there is now a modification to the Petroleum Act that allows geo companies to apply for leases and drill exploratory holes. All of the Perth metro is now leased.

These are NOT "hot rocks" they are abstracting hot water. One firm I know expects to be providing hot water for hearing and cooling applications within 3 years. We already have Challenge Stadium swimming pool using geo to heat water. Unless we are talking "district" level usage ( e.g. housing clusters, nursing homes etc, geothermal is more likely to be bigger scale commercial than domestic.

Re: Geothermal energy

PostPosted: Fri Sep 25, 2009 1:38 pm
by KingoftheWatt
Renew, I have a sneaking suspicion that Deni is talking about ground-source heat pumps rather than true geothermal here, and these are ideal for domestic level heating.... (sometimes ground sources-heat pumps are mistaken referred to as geothermal in the mainstream press). Apologies if I've got this wrong.

For clarification, heat pumps simply use the ground as a place to suck heat from, or to dump heat into. When they steadily suck heat, that heat is actually being replenished by the warmth from the sun. Ground-source heat pumps do this through big lengths of underground plumbing laid a metre or two beneath the surface.

Air-source heat pumps can also do a similar thing.

They are actually very efficient means of heating or cooling a house (for numbers, please see "Without Hot Air", by David MacKay, free download available at www.withouthotair.com/download.html)

Deni, the book mentioned above will give you some background on efficiencies. I can't comment on specific brands or anything available in Australia, but I believe that the technology works just as effectively no matter where you are as long as you can get the plumbing in.

Re: Geothermal energy

PostPosted: Fri Sep 25, 2009 6:36 pm
by renew
KoftheW you are probably right. We have a way to go before well have a grasp on the technologies.

Re: Geothermal energy

PostPosted: Fri Sep 25, 2009 10:00 pm
by Deni
Thanks King of the Watt. Ground source heat pumps for domestic homes are what I am looking at. Thanks for the link too, its very useful.
cheers
Deni

Re: Geothermal energy

PostPosted: Tue Sep 29, 2009 2:53 pm
by Millsy
Hi Deni,

I have looked into the domestic type of geothermal heating, cooling and hot water. The way it works is similar to how a fridge works although used backwards in a way. As far as i understand refrigerant is circulated into the ‘bores,’ usually you have 8-10 of them, they are all angled to enter the ground close together so it can be put in pretty much anywhere. The refrigerant is then compressed using some sort of compressor that then either heats water or air and is circulated through piping or ducts in either your slab, or ducted system. It is also used for heating water.

Although this system is meant to be very efficient i have not been able to find figures to work out cost of running, i do however have approximate costs for the system its self.

There is a company in Victoria called Energycore that does this. For a 3 bedroom house, to create hot water, heating and cooling you are looking at about $20,000 this may vary a bit depending on the site itself. This is rather more expensive than i had expected. For this cost you would want it to be VERY cheap to run and never to fail.

On the plus side, it is meant to be very efficient and the most economical of all air conditioning, having said that if you are designing a very thermally efficient house you WONT!! Need hardly any heating and NO cooling whatsoever, if it is designed well. ;)

Re: Geothermal energy

PostPosted: Tue Sep 29, 2009 7:12 pm
by Deni
Thanks Millsy for your reply. I've found some running costs and it does look attractive on that basis and I have been investigating the ground source heat pump option with Energycore but the upfront costs is around 60k for my four bedroom home which is far too prohibitive.
So now I'm investigating at air source heat pumps. There will be a solution at there somewhere! :D

Re: Geothermal energy

PostPosted: Tue Sep 29, 2009 7:57 pm
by Millsy
WOW 60K im not sure many could afford that, even if they could it sounds a very poor investment given the alternatives.

Re: Geothermal energy

PostPosted: Wed Sep 30, 2009 7:37 am
by Deni
Yes, definitely got to be many other better options out there at affordable costs.