| General > General Technical Chat |
| UK Carbon emissions per kWh. Surprising. |
| (1/3) > >> |
| paulca:
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 I find as you get older time seems to go faster and it's easy to get out of date, but the figures they are proposing for the UK fuel mix are something around 170g/kWh burning methane, 190g/kWh burning propane and 191g/kWh electricity.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. |
| IanB:
I read your post over and over again, but I can't understand what you are asking. What is your question? |
| tom66:
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. |
| jonpaul:
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 |
| SiliconWizard:
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 |
| Navigation |
| Message Index |
| Next page |