nicholastanguma
Los Angeles, San Francisco
Full disclosure: I pulled this post from Mike Veal over on pistonheads.com. It was a thread entitled, "How much longer will diesel be a viable option?"
No political wannabees or culture warriors need get themselves in a huff; this is just the science of the world's current technological limits from a logistical standpoint. Meaning, EV technology itself will likely become viable as a passenger vehicle option (how could it not?), but the power grids of even the planet's mightiest economies simply can't produce enough electricity to charge everyone's vehicles and keep lighting our housing infrastructure at the same time. Here's a linky to the entire thread if you're interested.
"We don't have the infrastructure to charge EVs.
This (from here) shows that cars, light vans and motorcycles used 12.9 million tonnes of petrol and 12.4 million tonnes of diesel in 2012.
For petrol the energy density is 45.8MJ/Kg, lets use an engine efficiency of 25%. So that's 45.8MJ/Kg * 12.9M Tonnes *1000Kg/Tonne * 0.25 = 147705000 GigaJoules per year that actually get used for propulsion. The other 75% is wasted as heat.
Similarly for diesel, energy density is 45.5MJ/Kg, but engine efficiency is higher at around 35%, giving : 45.5MJ *12.4M Tonnes *1000Kg/Tonne * 0.35 = 197470000 GigaJoules.
Our combined energy need to drive EVs is 345,175,000 GigaJoules per annum. But the EVs aren't 100% efficient. If we use a figure of 90% efficiency (combined efficiency of EV motor, battery, charger, national grid, it's a guess & a very generous one), that need rises to a more realistic 383,527,778 GigaJoules per annum.
Since the national grid capacity is measured in Watts and 1J is 1W for 1s, we divide the EV energy need in Joules by charging time to work out the wattage that the national grid needs to supply.
Time available is 1 year, which is 31,556,926 seconds.
But these magical EVs won't be available to be charged 24/7. So the load can't be spread evenly onto the national grid over any 24 hour period. Let's guess that of the 24 available hours per day, all the cars are out and about during daylight hours & get plugged in at night. I'm going to use 8 hours per day out and about, 16 hours plugged in.
That reduces the time available to 21,037,950 seconds.
So the potential EV load on the National Grid is 383,527,778 GigaJoules / 21,037,950 seconds = 18.23GW.
Our 2015/2016 capacity (p36) is about 75GW. So we need an extra 24%, but current spare capacity is a woeful 5%
Waving a magic wand and fixing the EV battery / range problems is only half the problem. We'd need a lot more power stations and a serious upgrade to the electricity distribution network. The cabling from generating station all the way to our houses may need replacing / upgrading."
No political wannabees or culture warriors need get themselves in a huff; this is just the science of the world's current technological limits from a logistical standpoint. Meaning, EV technology itself will likely become viable as a passenger vehicle option (how could it not?), but the power grids of even the planet's mightiest economies simply can't produce enough electricity to charge everyone's vehicles and keep lighting our housing infrastructure at the same time. Here's a linky to the entire thread if you're interested.
"We don't have the infrastructure to charge EVs.
This (from here) shows that cars, light vans and motorcycles used 12.9 million tonnes of petrol and 12.4 million tonnes of diesel in 2012.
For petrol the energy density is 45.8MJ/Kg, lets use an engine efficiency of 25%. So that's 45.8MJ/Kg * 12.9M Tonnes *1000Kg/Tonne * 0.25 = 147705000 GigaJoules per year that actually get used for propulsion. The other 75% is wasted as heat.
Similarly for diesel, energy density is 45.5MJ/Kg, but engine efficiency is higher at around 35%, giving : 45.5MJ *12.4M Tonnes *1000Kg/Tonne * 0.35 = 197470000 GigaJoules.
Our combined energy need to drive EVs is 345,175,000 GigaJoules per annum. But the EVs aren't 100% efficient. If we use a figure of 90% efficiency (combined efficiency of EV motor, battery, charger, national grid, it's a guess & a very generous one), that need rises to a more realistic 383,527,778 GigaJoules per annum.
Since the national grid capacity is measured in Watts and 1J is 1W for 1s, we divide the EV energy need in Joules by charging time to work out the wattage that the national grid needs to supply.
Time available is 1 year, which is 31,556,926 seconds.
But these magical EVs won't be available to be charged 24/7. So the load can't be spread evenly onto the national grid over any 24 hour period. Let's guess that of the 24 available hours per day, all the cars are out and about during daylight hours & get plugged in at night. I'm going to use 8 hours per day out and about, 16 hours plugged in.
That reduces the time available to 21,037,950 seconds.
So the potential EV load on the National Grid is 383,527,778 GigaJoules / 21,037,950 seconds = 18.23GW.
Our 2015/2016 capacity (p36) is about 75GW. So we need an extra 24%, but current spare capacity is a woeful 5%
Waving a magic wand and fixing the EV battery / range problems is only half the problem. We'd need a lot more power stations and a serious upgrade to the electricity distribution network. The cabling from generating station all the way to our houses may need replacing / upgrading."
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