Reply to post: Re: What about the downsides?

London mayor: Self-driving cars? Not without jacked-up taxes, you don't!

Alan Brown Silver badge

Re: What about the downsides?

"The "carbon emissions" are moved, not saved and may even increase due to grid losses, charging losses and battery losses"

Tank to wheel efficiency of most cars and busses is in the region of about 5% - less than 1% in stop start traffic.

Tank(furnace) to wheel efficiency of electric vehicles is around 35% and stop/start traffic makes little difference if they use regenerative braking.

The interesting part that goes with that is that the electricity cost of refining the fuel to run a car is about the same as charging an electric car.

Carbon emissions are a problem. Look up "Leptav Sea Methane Emissions" and then "Storegga slide" and then "Anoxic Oceanic Event". We're going to have to stop burning carbon sooner rather than later and not just for electricity (which only accounts for about 35% of carbon emissions).

This brings in some interesting problems:

1: To replace the other 65% of emissions (with electricity), you're going to need to increase electrical generation capacity by a factor of _AT LEAST_ 6, probably 8. Electric vehicle fleets alone will double the requirement at minimum, and replacing gas/oil heating systems will be as much again - which you CAN'T timeshift by much even with storage heating. Industrial processes will need considerably more electricity than a 1:1 reduction in carbon you might naively think, because a lot of it is making high quality heat.

2: Assuming perfect solar panels on every rooftop and windmills everywhere, renewables can _just match_ current electrical generation capacity (forget drax, it and its kin are greenwash which are destroying old growth forest at a prodigious rate)

3: Hydro is tapped out, tidal won't make enough different to matter. Electricity can only be economically transported about 1000-1200 miles before line losses and construction costs kill the feasibility of the project - less than 200 miles underwater (and underwater links top out around 2GW).

3a: That means "paving the desert" and using electrricity from there is a non-starter - for starters the deserts belong to african countries (colonialism writ large) and secondly the transmission lines _alone_ would be the largest engineering project in the history of humanity, with 75+% losses into Europe (No, superconducting cables are not practical. They need to be cooled and trenched, which is ok for 20 miles but not thousands)

4: If the developed world stopped using carbon tomorrow, the developing world has the capacity to make up the emissions and then some, whilst bootstrapping themselves to developed status.

The only logical path is nuclear and lots of it - to the tune of about 60 Hinkley points in the UK alone and deployment fo the same across the developing world.

By the time those reach midlife to end-of-life we (or rather the chinese, as they're the ones doing the lion's share of R&D) should have Molten Salt Reactors sorted and commercially viable. These are at least 100 times safer than current nuclear (which is already 300,000 times safer than coal) and break down conventional "nuclear waste"(*) - both the 99% viable stuff that comes out of a conventional reactor and the 90+% "depleted" uranium that's currently discarded after enrichment or turned into H-bomb casings/bullets, - leaving 1% waste output which is safe to handle in 100-300 years (5-10 for some byproducts, which are saleable commodities such as helium and other noble gasses. Anything "hot" or toxic goes back into the reactor melt pool for further breakdown)

(*) A conventional 800-1000MW reactor over a 60 year lifespan produces enough high level waste to fill a large swimming pool and is safe to handle for reprocessing in about 300 years (less if you wear gloves)

Ideally molten salt reactors will be ready long before conventional plants reach end of life, but we can't afford to sit around another 30 years waiting for them to be commercially viable and then 20 more to build the things. Carbon-emitting power plants need replacing now and we don't _have_ 50 years to sit around with our thumbs up our arses.

Yes, I'm aware that nuclear technology has drawbacks, but even with a worst case chernoybl event every decade(**) that'd be 50-60,000 deaths vs 500million or so if climate change gets bad and 2-3 billion if the atmosphere drops to 15-16% oxygen or less in the case of an Anoxic Event.

(**) The world's coal plants emit enough radium alone to equal the radiation output of several chernobyls each year. Making a fuss about nukes when that's going on is on par with panicking about plane crashes but not bothering to wear a seat belt when you're in the car.

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