BEV emmissions

GreatApe

Was asked in another thread so here you go full info with more data and less assumptions with the BEVs charged by CCGTs

Model 3 = 95g/KM*
E Golf = 107g/KM (a less efficient BEV which uses more electricity)
Hybrid Corrolla or Prius = 106g/km (real world users reporting 63mpg = 106g/km)

So even an efficient BEV only saves about 10g/km over a hybrid
And this is in a gas marginal grid. In a coal marginal grid the BEV is far worse Vs the hybrid

Calculations below willing to amend if you feel the assumptions or calculations are wrong

GreatApe

7,500 miles/Yr @ 4.2m/kWh = 1786 units
1.1KWh/d self discharge = 402 units
Annual winter heating = 200 units
Charging efficiency 85% = 2810 units out of your socket
Works out to 2.67 miles per KWH

Gas fired electricity :

Gas is 185g/KWh

Gas fired CCGT in the UK operate at 48.9% (this seems low but it's because CCGTs ramp and down to meet demand so they seldom hit their peak efficiency stated by the CCGT manufacturers) here is a link to the efficiency before someone challenges me and say they are 62%

185g/kWh @ 48.9% efficiency @7% loss in grid = 407g/kWh in your socket

407g/KWh / 2.67 miles/kWh / 1.6 to convert miles to km = 95 grams / km

1961Nick

We clearly need more windmills (or nukes) as a matter of urgency ...

GreatApe

1961Nick wrote: »

We clearly need more windmills (or nukes) as a matter of urgency ...

I don't see the UK building anymore nukes than the two reactors under construction but we could potentially save the old nukes to live another 10-15 years which would be very very significant

For comparison switching every single UK oil car to BEVs would save about 26 million tons of carbon per year. Saving the old nukes would save 25 million tons per year. Pretty much exactly the same

Only saving the nukes to live another 10-15 years is possible while converting the entire stock of cars to BEVs is not remotely possible

GreatApe

1961Nick wrote: »

We clearly need more windmills (or nukes) as a matter of urgency ...

I'm quite pro offshore wind power it works reasonably well in the UK and I'm pro sending less money to net gas exporters so am willing to pay a little more for offshore wind rather than foreign gas. But I'm aware you can't build infrastructure overnight it will take time

The 2030 target of 30GW seems appropriate the 2040 target maybe 50GW will be possible depending on how things evolve. And yes BEVs start making sense once the UK has substantially more wind power but that's more than a decade out as the next 10 years will mostly be spent trying to cover the lost nuclear output

GreatApe

I was surprised by how low the efficiency of CCGTs are in practice relative to their advertised efficiency
49% real Vs advertising for some models as high as 62% but I guess it's like the difference between mpg on steady state motorway Vs start stop urban traffic.

1961Nick

GreatApe wrote: »

Only saving the nukes to live another 10-15 years is possible while converting the entire stock of cars to BEVs is not remotely possible

We don't need to convert anything like 100% of vehicles to BEVs to have a major impact. If you delved into the figures, you'd probably find that 75% of the emissions come from 25% of the vehicles. All we need to do initially is to target the low hanging fruit.

GreatApe

1961Nick wrote: »

We don't need to convert anything like 100% of vehicles to BEVs to have a major impact. If you delved into the figures, you'd probably find that 75% of the emissions come from 25% of the vehicles. All we need to do initially is to target the low hanging fruit.

But you don't get an emmissions savings from BEVs Vs efficient ICE as per this thread a hybrid gets 106g/km while an E Golf gets 107g/km and a model 3 gets 95g/km. When you plug in a Tesla into a super charger and pull 250KW from the grid that's 250KW more from a gas station chucking more methane into the turbine

You are just shifting emmissions from oil in your tank to gas in a powerstation (or coal of the local grid is Coal) In marginal coal grids like Germany China Poland India Japan Australia Indonesia S-Africa Korea Russia pretty much the rest of the world is a mix or fully marginal coal and as such you can add 50% to the emmissions figures above for BEVs

Where did you get this 75% of transport emmissions from 25% of vehicles?
Fuel duty = 58p government takes £27 billion from that tax = 10 billion gallons
Estimating 33m UK cars and bikes at 7,500 miles/yr & 40mpg average = 6.2 billion gallons
The remaining 3.8 billion gallons will be vans and trucks and HGVs
So as an estimate 38% of fuel is used by non cars


Also as said already if you electrify HGVs it's not necessarily going to cut emmissions they are already pretty efficient getting some 600g/km so a Tesla HGV would need to get at least 0.7 miles per KWh to match a normal oil HGV in a gas heavy grid or 1.4 miles per KWh in a coal heavy grid

GreatApe

If the average CO2 emissions of a manufacturer's fleet exceed its target in a given year, the manufacturer has to pay an excess emissions premium for each car registered.

From 2019 on, the penalty will be €95 for each g/km of target exceedance.

The EU regulations are for 95g/km for cars by 2021 onwards

If they enforce these figures for realistic mpg figures then we will see mostly hybrids come 2021 or the manufacturers will have to pay the €95 euro/gram fine. Therefore an SUV at 140g would pay €4,275 fine while the hybrid pays €0 and presumably VAT will apply on top

GreatApe

1961Nick wrote: »

All we need to do initially is to target the low hanging fruit.

The lowest of the low hanging fruit is extending the old nukes lives by a decade or two
60TWh @ 400g/KWh saved in not burning gas in a CCGT = 24 million tons

It's equal to the electricity consumption of 20 million homes

This is equal to taking 16 million old cars off the road

michaels

We already have curtailment and negative electricity prices and the technology to prioritise EV charging when this happens so already the assumption that we should use marginal gas generation co2 when calculating emissions from evs is already floored and will become increasingly inaccurate. I suspect currently curtailment is increasing more quickly than bev usage.