Electric cars

[00slk]

A car transporter fire involving seven electric vehicles has shut part of the M1. The blaze broke out at 13:40 GMT on Monday and carriageways between junctions 26 and 27 southbound were closed. No injuries were reported and no other vehicles were involved, Nottinghamshire Fire and Rescue Service said.

Well that saves 7 people from buying them......

 

[LostKiwi]

Hydrogen isn't a good choice - it has a low volumetric energy density. It's true that there is roughly 3 times as much energy in 1Kg of Hydrogen as there is in 1kg of Petrol. The problem is that whilst 1Kg of Petrol occupies about 1.2L of space, 1Kg of Hydrogen occupies 11m^3 (= 11,000L). So you have to compress it to get it down to a usable volume. You end up with a pressure tank that weighs more than 10 times the mass of the hydrogen that it contains, with the gas inside stored at 300-700 bar. A typical car tyre is only inflated to between 2 (29psi) and 2.5(36psi) bar, so we're talking about more than 100 times the pressure of air inside a car tyre.

Hydrogen also has a very small molecule size, which means it can leak through gaps that larger molecules like Petrol or Natural gas cannot. That means it get adsorbed into the skin of the tank itself, and in some cases it can passing directly through the skin of metal pipes and tanks. It also causes Hydrogen embrittlement, making the tank itself fragile, and frankly dangerous.

All this makes it difficult to transport safely and keep contained in any tanks.

The other issue with hydrogen is efficiency.
Currently hydrogen is produced in one of two way.
1st way is through cracking the hydrogen off carbon atoms in oils. Problem is it requires oil and generates lots of CO2 so not a viable answer.
2nd way is to use electrolysis of water. This is around 80% efficient. Once we have the hydrogen we need to use it to generate power.
We can use it in an internal combustion engine. At best this is 50% giving at best 40% overall (80% of 50%). We can use fuel cells but they have a typical efficiently of 60% and a maximum theoretical efficiency of 90% giving overall typical efficiency 48% to a maximum of 72%.

Battery EVs on the other hand are around 95% efficient now with an overall efficiency of 76%.

Any system that converts electricity to hydrogen to electricity cannot be as efficient as one that does not use double conversion.

Add to that the issues already mentioned and it just doesn't make sense to use hydrogen in private motor vehicles.

 

[NJS5]

 

[Judwin]

The other issue with hydrogen is efficiency.
Currently hydrogen is produced in one of two way.
1st way is through cracking the hydrogen off carbon atoms in oils. Problem is it requires oil and generates lots of CO2 so not a viable answer.
2nd way is to use electrolysis of water. This is around 80% efficient. Once we have the hydrogen we need to use it to generate power.
We can use it in an internal combustion engine. At best this is 50% giving at best 40% overall (80% of 50%). We can use fuel cells but they have a typical efficiently of 60% and a maximum theoretical efficiency of 90% giving overall typical efficiency 48% to a maximum of 72%.

Battery EVs on the other hand are around 95% efficient now with an overall efficiency of 76%.

Any system that converts electricity to hydrogen to electricity cannot be as efficient as one that does not use double conversion.

Add to that the issues already mentioned and it just doesn't make sense to use hydrogen in private motor vehicles.

Yes, and no.

For a 'renewable' system to be stable you have to be able to generate (more than) 100% of the peak demand, 100% of the time. Solar only works when the sun is shining, and wind only works when the wind is blowing. If Corrie and the footie both end at 8pm on a calm winters night then renewables can't help. However, what you can do is build (say) 200% wind capacity, and store the excess energy whilst the sun is shining and the wind is blowing. Batteries are one way, pumped hydro storage another, and electrolysing water to make Hydrogen is another.

Whilst storing the energy will never be as efficient as using it straight away (for all the reasons you state), if you're capable of generating (say) 200% of peak capacity then the stuff you store is effectively free - or at least a lot cheaper & greener than the other options. But you do need a way to store the energy (which isn't free), and a way of using it (also not free). Converting the Hydrogen back to electricity is best done in a few large power stations, not in millions of individual cars IMV.

 

[brandwooddixon]

With people using bio digesters to produce methane for power and talk of capturing burps and farts from livestock, perhaps having a system of cracking hydrocarbons to produce hydrogen is the way forward.
Having a car powered by such a process, with it leaving a trail of water and charcoal briquettes in its wake has a perverse appeal to my sense of humour.

 

[EmilysDad]

With people using bio digesters to produce methane for power and talk of capturing burps and farts from livestock, perhaps having a system of cracking hydrocarbons to produce hydrogen is the way forward.
.....

If only Gary at work could harness his farts ..... he'd have free transport for life!

 

[ajlsl600]

Still the elephant in the room is the (lack of) electricity infrastructure. Combine EVs with ASHP that we are being encouraged to fit instead of fossil fuel boilers and very quickly the infrastructure is overloaded and will be unable to support everyone's needs. It is not just the power cables but also the sub stations, transformers etc. What we are not seeing is any plan to tackle this. In my road the poles already carry 2 x 415V cables and phone lines for the village and that is the max capacity for the poles because of weight according to UK Power. There is not the physical capacity for everyone in the village to have ASHPs, let alone 7kW chargers. I was told that in my road of 10 houses there is only spare capacity for about 3 x 7kW chargers on the existing supply, that equates to about 5/6 ASHPs and it will be first come first served and with no plan for any upgrade it could be some years before there is adequate capacity for all houses to go EV/ASHP.

Another well thought scheme. Soon lecky will cost as much as fuel its trying to replace diff is ice will go 2or more x distance.. Will " my car ran out of lecky" me a valid reason to be late or absent from work lecky and petrol best way until hydrogen take over. And I believe it will.

 

[ajlsl600]

How charge car when frogs reduce, cut power exports. We have had a number of knee jerk reaction governments for long and as seen latest mob hav basically kicked the ball into the long grass for after next mob move in. Its "broken Britain" on many fronts. I near see it every 3,5 month leave cycle now, yet another sign of decay.
My mother fell at home recently severely stripped skin from shins, she 88. Ambulance was 11 hrs. She was on floor 7 of them until brother arrived local a and e 100 metres away closed w ends evenings .