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Author Topic: Realistic CO2 emissions for electricity  (Read 31864 times)

Ben

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Realistic CO2 emissions for electricity
« on: July 25, 2007, 02:38:05 PM »
I'm seeking a realistic reputable referenceable figure for  lifecycle CO2 emissions equivalent per kWh electricity generated (or supplied) in the UK.

 kgCO2-e/kWh el

My research shows that it will be approx 1kg but this is based on some very rough assumptions which aren't sufficiently reputable and referenceable.

It seems that everyone uses the figure of 0.43kgCO2/kWh. This figure is fine if one is trying to pretend that we are going to meet Kyoto targets, but for the purpose of assessing the CO2 savings of heatpumps compared to oil boilers or renewables it is useless.

If anyone has done any research or knows anyone who has done research into the lifecycle CO2 emissions/kWh electricity in the UK can they please contact me. Acces to such a figure is essential  for anyone attempting to make fair and unbiased decisions in this industry. Knowledge of this figure would contribute to a huge improvement in the choice of technologies in the renewables sector and hence the reduction of CO2 emissions.

Thanks
Ben



Jamie B

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Re: Realistic CO2 emissions for electricity
« Reply #1 on: July 26, 2007, 05:06:32 PM »
The 0.43kgCO2/kWh has recently been updated by Defra to come more into line with actual emissions (the 0.43 figure was to be used by companies from an ETS point of view).

The correct figure is now 0.527kgCO2/kWh

http://www.defra.gov.uk/environment/business/envrp/pdf/conversion-factors.pdf

As for lifecycle emissions I assume you mean including construction of power stations etc. I haven't seen any studies or figures to that effect but would be interested to see them.

Hope that helps

Mark Brinkley

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Re: Realistic CO2 emissions for electricity
« Reply #2 on: July 28, 2007, 11:20:25 AM »
Thanks for the link to the DEFRA site. Very interesting data. I am not sure you are right about the electricity figures going up from 0.43kgCO2/kWh. The long term marginal factor remains at the lower figure. However, by way of explanation, it says:

>>The long-term marginal factor assumes that, over a long time period (a decade or more)
avoided electricity use will displace generation at a new Combined Cycle Gas Turbine
(CCGT) plant. Policies and measures that produce long-term reductions in electricity use
should therefore use this factor to assess what carbon saving will result. When calculating
emissions reductions based on long term investment decisions (for example, building zero
carbon housing or business premises, investing in on-site renewables etc.) companies
should use this factor. Carbon savings used for the purposes of Climate Change Agreements
(CCAs) have historically been calculated using this factor, and it should continue to be used
for this purpose.

Can anyone explain what on earth this means?

Jamie B

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Re: Realistic CO2 emissions for electricity
« Reply #3 on: July 30, 2007, 10:01:59 AM »
Sorry I didn't explain myself very well. I believe that the 0.43 figure was intended to be used by companies to evaluate their emissions over time and provide a constant factor so as to make year-on-year comparisons of emissions possible.

There was some more blurb on this in the old company guidelines:

"The factor for electricity has been changed slightly from the previous guidelines to come into line with calculations for the Climate Change Levy Agreements and future requirements for Emissions Trading. It was calculated on the projected fuel mix for the grid 1998-2000. Actual figures may differ from the projections, but to help with year on year comparisons we plan to use a constant value for the purposes of these Guidelines until the year 2010."

http://www.defra.gov.uk/environment/business/envrp/pdf/envrpgas-annexes.pdf

The new (i.e. recently published) 0.527 figure has been calculated by AEAT based on actual CO2 emissions and electricity generated from UK power stations in 2005. If you're looking at what the saving is now, then 0.527 is what you're looking for. For long range projections it looks like 0.43 is the one.

If you need more information I'd suggest you drop them a line. They'll be happy to help you out:

http://www.defra.gov.uk/environment/business/envrp/contact.htm

David OLIVIER

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Re: Realistic CO2 emissions for electricity
« Reply #4 on: July 31, 2007, 10:54:10 AM »
Given that gas consumption for electricity generation is slightly declining and coal use has been rising (0.9 kg/kWh), can someone explain why we should use 0.43?

Also it's become clear from someone else making an enquiry to DTI that the 0.43 figure excludes electricity losses in transmission and distribution. These are 8% as an annual average and are over 20% on some routes at winter peak (which would be more appropriate to calculations of the emissions from electric space heating). Does the 0.53 exclude T&D losses?

Does it also include losses in production of fossil fuels. For instance with coal, oil and gas, between 5% and 9% of the primary energy in the fuel at the point of extraction from the ground is consumed in refining oil, pumping gas through pipes, delivering coal by lorry, etc, etc.

D.

Mark Siddall

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Re: Realistic CO2 emissions for electricity
« Reply #5 on: July 31, 2007, 12:45:58 PM »
David,
You could also do with adding to that list some CO2e that will cover 1) the methane emissions associated with mining the coal in the first place 2) where the coal originates from/will come from (UK coal is dirtier than some places but is no doubt cleaner than others.)

Mark

Jamie B

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Re: Realistic CO2 emissions for electricity
« Reply #6 on: August 01, 2007, 04:01:46 PM »
David, the 0.527 factor is...

"Based on 46.97 MtC for major power producers from NAEI for 2005 (excludes overseas territories and crown dependencies to be consistent with DUKES), divided by ‘Major power producers’ (supplied - gross) plus 'Other generators' thermal and non-thermal renewables supplied from Table 5.6 and total losses of 7.5% from paragraph 5.49 DUKES 2006"

http://www.defra.gov.uk/environment/climatechange/uk/individual/pdf/actonco2-calc-methodology.pdf P25

So it looks like this would not include emissions associated with production, transportation etc but does include transmission losses. Unfortunately it would be very difficult to calculate full lifecycle CO2 emissions for electricity generation.

I think the 0.43 figure looked reasonable at the point when it was chosen (in 1998 the carbon factor dropped to 0.48) but as you say, a return to coal has made the actual carbon factor creep up.

Tahir

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Re: Realistic CO2 emissions for electricity
« Reply #7 on: August 01, 2007, 05:00:29 PM »
I think the 0.43 figure looked reasonable at the point when it was chosen (in 1998 the carbon factor dropped to 0.48) but as you say, a return to coal has made the actual carbon factor creep up.

How would a return to nuclear affect  the figures?

Mark Siddall

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Re: Realistic CO2 emissions for electricity
« Reply #8 on: August 01, 2007, 06:09:43 PM »
I mentioned the N-word at the conferance (during Nick's presentation). I nearly got roasted alive.....and I wasn't even saying that it was a good thing (which it ain't.)
More resent information suggests that renewables offer greater energy security AND, if sufficiently diverse, are more reliable. Nuclear powerstations have to shut down for 30 or say days each year to refuel, if the grid goes down...as 2003 in the States then all the reactors have to be shut as a precautionary measure. It took some time before they were all up and running again due to a number of nasties that need to be carefully managed....Think of the damage to GDP and renewables start to sound like a good buy.
PVs offer 'good' elec during the day and wind offers 'good' supply at night. Spread over a suitable area then the grid can help to manage any troughs in supply. With the right switching as the supply is more localised if the grid did go down neighbour hoods could still function.

(So they say at least.)
Mark
« Last Edit: August 01, 2007, 06:11:34 PM by Mark Siddall »

Jamie B

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Re: Realistic CO2 emissions for electricity
« Reply #9 on: August 02, 2007, 02:17:07 PM »
Nuclear would no doubt reduce the factor but personally I think it would be a mistake to expand nuclear power. We're going to be handing down to our children a certain amount of climate change. Let's not add even more nuclear waste and weapons proliferation into the mix as well.

I would also add to what Mark said above that there is such a vast array of renewables options out there from large scale centralised generation (wind, wave, tidal, CSP), through medium sized decentralised CHP (both cogen and trigen) down to all the many forms of microgen, that we can do without nuclear power.  We also have the North Sea oil fields available for sequestration so I see no reason why we can't combine the two successfully. Finally I don't believe that nuclear power is financially viable without massive public support.

I haven't read it yet but this book looks good if you want to read more about the generation side of things:

http://www.waltpatterson.org/ktlointro.htm

I went to its launch a few weeks ago and he is a fascinating guy with some very interesting ideas about decentralised power generation.

Tahir

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Re: Realistic CO2 emissions for electricity
« Reply #10 on: August 02, 2007, 02:30:01 PM »
I don't believe that nuclear power is financially viable without massive public support.

I'm shocked that the govt don't buy into this view, I;d have thought this was (in completely objective terms) one of the main reasons why it's a no go.

Ben

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Re: Realistic CO2 emissions for electricity
« Reply #11 on: August 13, 2007, 04:45:38 PM »
Thanks to everyone who replied. Some useful leads and references.

My conclusions:
I've not been able to find reasonably accurate lifecycle kgCO2/kWh electricity figures in the for the UK. This  astounds me!

One result of not having this figure is that we are spending £millions funding heatpumps when in reality they are probably contributing to more CO2 emissions than oil or gas boilers. If we had a reputable lifecycle figure we would fund genuine renewables and energy efficiency projects instead.

There must be many other examples where government funding is misguided because of this bias.

Indeed using such a low emission factor is surely providing a barrier to clean up the electricity generation industry.


I have come  to agree with William Orchard in that we should use the marginal coal factor or 0.928kg for renewable projects. Infact i suggest we go further. This figure doesn't include transmission losses or supply side CO2 emissions. If we added these plus the methane emissions from coal extraction plus infastructure CO2 footprints of fossil electricity plant and distribution then the marginal coal  figure would become of at least 1.5kgCO2/kWh, perhaps much more.

We need to find and use such a figure if we are to fund woodfuel, wind and solar projects over heatpump projects.

I have a project in Scotland where a woodchip boiler may replace mains electic heating. If we use the 0.43 figure the project wont go ahead becase the unit cost of CO2 emissions reductions is too high. If we use William Orchards figure of 0.928kg then the unit cost of CO2 emissions reductions will be low enough for the project to go ahead.

I suggest that the  0.43kg and 0.527kg figures are not fit for purpose as the dash for gas didn't happen and because it is absurd to consider nuclear power to be zero carbon, and because we have to consider lifecycle emissions across the board.

The 0.527kg figure is supposed to include 7.5% transmission losses but having looked into Dukes 2006 i am not certain that it does. Does  the 0.527kg figure take the energy industry consumption into account?

Why aren't people demanding that DEFRA or whoever come up with a genuine electricity CO2 emissions factor? How can we begin to do something about climate change without such a figure? It seems that we'll continue to go backwards until we get realistic about this.

Ben Hargreaves

Jamie B

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Re: Realistic CO2 emissions for electricity
« Reply #12 on: August 15, 2007, 10:41:27 AM »
Ben

What you're asking for is an exceptionally difficult task! Lifecycle studies are very involved and very complex things to do and don't come cheap. Doing one for the whole UK electricity generation industry would be tricky to say the least.

You're aboslutely right though, they do need to be done (in my opinion it should be a requirement for all products from all companies in the UK). It's especially important for products which have a sustainability aspect because we frequently can't say for certain that one technology will be better than another.

Also, remember that in-use energy consumption generally dwarfs the other phases of the lifecycle (power drills excepted!). I would expect this to be even more the case for electricity generation.

If you do want to contact anyone then I would suggest you drop BERR (dti that was) a line rather than defra.

I know the person who calculated the 0.527 figure so can get a difinitive response on transmission losses for you. I would expect it doesn't take into account upstream emissions. I believe Table 5C of DUKES 2006 has an error in it so don't put too much stock in that.

Ben

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Re: Realistic CO2 emissions for electricity
« Reply #13 on: August 15, 2007, 04:14:34 PM »
Thanks Jamie, yes i don't doubt it's difficult!

Yes please can you please ask your contact what is and what isn't included he 0.527 figure. Transmission losses? Electrical energy consumed by the electricity industry? Also could you please ask them if they still use zero CO2 for nuclear? And just possibly could you ask them if they can  come up with a realistic reputable lifecycle figure!

Following emails with David Olivier and William Orchard (thanks) i have decided to use 2 scenarios in my calculations: a) 0.527kg and b) 1.085kg

The latter is derived from the factor for marginal coal 0.928kg plus supply side losses 5% (from Proffesor Peter F Chapman 30 years ago for want of anything more up to date) plus average transmission/distribution losses of 10% .

Ben


 

Jamie B

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Re: Realistic CO2 emissions for electricity
« Reply #14 on: August 16, 2007, 09:43:18 AM »
I'll see what I can do