Author Topic: UK Carbon emissions per kWh. Surprising.  (Read 1596 times)

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Offline paulcaTopic starter

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UK Carbon emissions per kWh. Surprising.
« on: October 12, 2022, 03:57:27 pm »
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1083857/2022-ghg-cf-methodology-paper.pdf

It's a long read, but the parts I went looking for were the conversion ratios between burning methane (LPNG) for heat and using resistive heating elements (for example).  CO2 / kWhe versus CO2 / kWht

There are tables and tables and tables and they all seem to give different values depending on which perspective they are looking at it from.  The surprising thing is how rapidly the ratio has been falling.

I find as you get older time seems to go faster and it's easy to get out of date, but the figures they are proposing for the UK fuel mix are something around 170g/kWh burning methane, 190g/kWh burning propane and 191g/kWh electricity.

I'm like, what?  (watt?).  How?  When?

The UK has a fuel mix of about 40-45% natural gas for electric generation.  CCGT plants are about 60%-70% thermally efficient and the turbine generators are, what?, 90% efficient?  Then (from the report) about 8% grid loss.

I'm probably butchering the maths, but for each kWh electric, 0.45kWh is generated from gas.  The overall generation efficiency is 60%*90%*92% = 0.496.  So to generate 0.45kWh it will need to consume roughly 0.9 kWh of gas.

That works out.  Doesn't it?  That 1kWh of electricity, in the UK, currently "costs" 1 kWh of gas.  That would not eat into the GOP of heat pumps that much.

I suppose I'm admitting I was wrong for quite a while.  I thought it was just 3:1 * carbon fuel mix %.

Either that or there is a large amount of greenwashing going on, or my maths or assumed figures (for generation efficiencies for example) are way out.  The others are from the paper.
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Online IanB

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #1 on: October 12, 2022, 04:22:33 pm »
I read your post over and over again, but I can't understand what you are asking. What is your question?
 

Online tom66

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #2 on: October 12, 2022, 04:46:55 pm »
The UK grid is so clean that you can drive a Tesla Model X SUV (a ridiculous vehicle that weighs about 2.5 tonnes) and come ahead of the emissions profile of a moped running on petrol

Moped on petrol ~120mpg[UK]:  emissions per gallon of petrol  ~10.9kg so 1 mile ~90g CO2eq
Model X on ordinary UK grid electricity at 200g/kWh:  2.5 miles/kWh in worst typical case  so 1 mile ~80g CO2eq

Ignoring tyres/maintenance for simplicity (Model X probably loses when you consider those, but I expect only just!)

Heat pumps would make sense because their COP is high.  1kWh electricity may require about 1kWh of gas (assuming your calculation is correct) but COP of 3 is achievable easily.  Meanwhile average gas boiler manages about 80% efficiency in typical installation.
 

Offline jonpaul

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #3 on: October 13, 2022, 06:44:31 am »

the question seems irrelevant

The main CO2 and warming source is animals grown to be slautered and eaten, politicians and governments

Non Western /US UK countries will continue to use coal, gas, oil, frac for decades or forever,  to keep the governments in power.

Real solution is nuclear power


jon



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Offline SiliconWizard

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #4 on: October 13, 2022, 07:56:51 pm »
Methane is the most problematic greenhouse gas. https://www.sciencelearn.org.nz/resources/3132-methane-a-greenhouse-gas

Sure the poor cows emit a lot of it. As natural gas, this gets released in the atmosphere as is only if there are uh... leaks. :popcorn:
But otherwise, burning natural gas is a lot less pollution than burning other kinds of fossile fuels. (Natural gas is mostly methane.)

https://group.met.com/en/mind-the-fyouture/mindthefyouture/natural-gas-vs-coal
 

Offline james_s

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #5 on: October 13, 2022, 08:35:43 pm »
It's too bad we can't easily harness all that methane that cows produce. It seems less damaging to the environment to burn it than to release it into the atmosphere, and it's useful stuff too.
 

Online tom66

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #6 on: October 13, 2022, 08:45:14 pm »
There are farms around here that collect the, err, "cow leavings" and recycle it to produce biogas.  I recall the problem with this, besides the cost per kWh, is that most of the methane comes from the burp and not the opposite end.  So you need to put a mask on a cow then, to capture the methane.  Good luck with that.
 

Online IanB

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #7 on: October 13, 2022, 08:49:54 pm »
There are farms around here that collect the, err, "cow leavings" and recycle it to produce biogas.  I recall the problem with this, besides the cost per kWh, is that most of the methane comes from the burp and not the opposite end.  So you need to put a mask on a cow then, to capture the methane.  Good luck with that.

The waste can be digested (composted) to produce methane gas and leave a nitrogenous fertilizer behind. This may not scale to large amounts of energy, but it works for small scale energy production.
 

Online Gyro

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #8 on: October 13, 2022, 08:54:14 pm »
There are farms around here that collect the, err, "cow leavings" and recycle it to produce biogas.  I recall the problem with this, besides the cost per kWh, is that most of the methane comes from the burp and not the opposite end.  So you need to put a mask on a cow then, to capture the methane.  Good luck with that.

https://www.eevblog.com/forum/dodgy-technology/holy-cow!/  ;)
Best Regards, Chris
 
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Online tszaboo

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #9 on: October 13, 2022, 09:29:47 pm »
There are farms around here that collect the, err, "cow leavings" and recycle it to produce biogas.  I recall the problem with this, besides the cost per kWh, is that most of the methane comes from the burp and not the opposite end.  So you need to put a mask on a cow then, to capture the methane.  Good luck with that.

The waste can be digested (composted) to produce methane gas and leave a nitrogenous fertilizer behind. This may not scale to large amounts of energy, but it works for small scale energy production.
1.) I believe recent studies found that adding like 10% of algae into the diet of cows makes them emit almost no methane.
2.) So actually, all the vegan people should be glad that we eat meat. The more meat we eat the less cow remains, the better it is for the environment. This is simple math. 8)

OP: Also this trend looks good.
 

Online tom66

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #10 on: October 13, 2022, 10:03:42 pm »
I don't generally agree with much of what the UK government has done but they have really got the transition to renewables right - it's happening with rapid pace.  I'd like to see more joined-up thinking in the area of storage (to go fully renewable, we need *days* of storage capacity) and smart consumption (spearheading some kind of smart device standard would be great, we need dishwashers and washing machines etc that run at the best time)
 

Online themadhippy

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #11 on: October 13, 2022, 10:30:34 pm »
Quote
I don't generally agree with much of what the UK government has done but they have really got the transition to renewables right - it's happening with rapid pace.
even though there trying to stop farmers from building new solar farms?They make the excuse the land is needed for food production,but then another report comes out asking farmers start growing more biofuel products to  get burnt in power stations
 
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Offline SiliconWizard

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #12 on: October 13, 2022, 10:37:04 pm »
It seems to be working very well indeed. :popcorn:
 

Online tom66

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #13 on: October 13, 2022, 11:27:16 pm »
Quote
I don't generally agree with much of what the UK government has done but they have really got the transition to renewables right - it's happening with rapid pace.
even though there trying to stop farmers from building new solar farms?They make the excuse the land is needed for food production,but then another report comes out asking farmers start growing more biofuel products to  get burnt in power stations

Perhaps this current iteration of the government notwithstanding then - though given opinion polls do we think they will make Xmas?!
 

Offline paulcaTopic starter

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Re: UK Carbon emissions per kWh. Surprising.
« Reply #14 on: October 14, 2022, 02:33:10 pm »
The UK just moved all it's industry and manufacturing to other countries to emitt the CO2 for them over there.
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