Comments on: ground source heat pumps not so green

By: shane

shane — Fri, 13 Aug 2010 12:50:01 +0000

ohhh, just noticed the figure for Natural Gas is 0.01799 kg/CO2/kWh indirect emissions (DEFRA 2010, Annex 1, Table 1c rather than 1b as above)

By: shane

shane — Fri, 13 Aug 2010 12:09:23 +0000

B Whittle,

It’s an old wifes tale to include biomass transport like this as all fuels have indirect emissions not just biomass and the Grid electricity figure used excluded these emissions. Here’s the latest figures;
Wood Pellets 0.03895 kg/CO2/kWh indirect emissions (DEFRA 2010, Annex 9, Table 9C)
Natural gas 0.1968 kg/CO2/kWh indirect emissions (DEFRA 2010, Annex 1, Table 1b)
Electricity indirect 0.07185 kg/CO2/kWh indirect emissions (DEFRA 2010, Annex 3, Table 3C)

For example Natural Gas has 5 times more indirect emissions than Wood pellets while electricity has double.

Policywonk,

proper wonky stuff. the idea of advocating an inaffective solution due to some capitalist money exchange is very frustrating.

Shane

By: Geothermal heat pumps green or not so green? « Domestic Futures II

Geothermal heat pumps green or not so green? « Domestic Futures II — Thu, 14 Jan 2010 03:58:04 +0000

[...] January 13, 2010 by cbuster “At first glance, the green credentials of ground source heat pumps (GSHPs) look unquestionable: because you’re harvesting free heat from the ground, you can get up to four times more energy out of the system than you put into it. Sure, it runs on electricity, which is more carbon intensive than gas, but because of this favourable ratio of output-to-input (called the COP for coefficient of performance) the system should still emit less carbon than a gas boiler – in theory.” Casey Cole [...]

By: Policywonk

Policywonk — Mon, 28 Dec 2009 18:05:02 +0000

Increasing the use of electricity will have no effect on the level of emissions within the EU Emissions Trading system – the overall level of emissions is capped across the industries covered for the whole of Europe. Increasing the use of electricity by installing a GSHP will marginally increase the cost of allowances, this may increase emissions in the UK, but over the whole system the market for allowances, and their marginal increase in price will incentivise compensating abatement elsewhere in the scheme. Switching from fossil fuels to an electric heating will therefore reduce the global level of greenhouse gas emissions by the reduction in domestic gas/oil use. The savings are the total emissions associated with the alternative gas or oil boiler! Consideration of the bigger picture is essential. DECC have adopted this approach in all their analysis.

By: B Whittle

B Whittle — Fri, 17 Oct 2008 06:25:55 +0000

Another intersting (!) point is that SAPS calcs don’t take into account the energy taken to deliver fuel to a biomass boiler, something that often appears to be forgotten when it comes to these issues

assuming 15-20 year lifespan of a biomass boiler thats a lot of lorry journeys carrying 1-25tons of fuel depending on the scale of the installation

lifespan of a good heat pump should be similar or higher than this

By: B Whittle

B Whittle — Fri, 17 Oct 2008 06:20:38 +0000

Interesting post!

but unless I have misunderstood your figures Jason is right about your split of hot water energy vs space heating energy. The government suggests that this is generally around 20/80 as Jason suggests, though as buildings become better insulated this figure pushes towards 25/75

The answer is to heat domestic hot water using solar thermal and back up using an immersion heater on a timer to come on in the evening, a strategy advocated by Kensa heat pumps for a long time (no I don’t work for them, I install solar systems!). Heat pumps should not be used to heat DHW

There appear to be many heat pump manufacturers suggesting performance will be much better than is realistic, and I worry about a general lack of understanding of the technology by architects and specifiers. I think ultimately the people selling heat pumps are to blame as you can find many of them suggesting heating DHW is perfectly acceptable.

I have heard that one manufacturer claim that it sells a 14kW heat pump which is in fact an 8kW output heat pump with a small cylinder inside the casing and 2x 3kW immersions, so in fact not a true 14kW heat pump at all.

By: Heat pumps | my barn conversion

Heat pumps | my barn conversion — Thu, 09 Oct 2008 20:56:53 +0000

[...] Other Resources Grants may be available for UK installations see http://www.lowcarbonbuildings.org.uk/micro/ Proceed with caution where gas is available according to carbonlimited.org [...]

By: IGnatius T Foobar

IGnatius T Foobar — Mon, 06 Oct 2008 18:45:31 +0000

Carbon intensity of the grid leveled off because the eco-lobby continues to villify nuclear energy. It is vitally important to build out lots of nuclear energy sources in order to fill the gap between fossil fuels and sustainable/renewables.

By: G.Evans

G.Evans — Fri, 08 Aug 2008 08:08:22 +0000

How does the embodied energy and embodied CO2 of conventional gas fired appliances compare with GSHP. All that Augering, excavation and pipework must attract a premium unless energy piles are used. Has anyone done a whole life payback exercise for this ?

By: mel starrs

mel starrs — Wed, 13 Feb 2008 11:22:51 +0000

GSHP never do well when compared for purely heating, but the story changes when cooling is added. Now, I am most definitely not advocating cooling in the UK (yet) for the domestic market, but for those clients who demand cooling (think high end of the market, especially in city apartments where opening windows is less than desirable in the summer due to grime), then GSHP becomes more efficient than standard splits (or did last time I did the calcs).

Great post as always – ever think of pulling these altogether as pdf’s?