Electric cars - how 'green' are they?

boogieman

Fretwired said:

crunchman said:

Fretwired said:

Electric will work in sunny California (cars will be able to charge using solar energy as they drive or are stationery)

No.

Good sunlight is about 1000W (1kW) per square meter.  Let's say you have 2m x 2m on top of the car where you can mount panels that's 4m2 so 4kW of sunlight.  Even if we allow for really good solar panels with an efficiency of 25% (better than anything on the market now) you would only generate 1kW of electricity.  I think the current Tesla has a battery of 60kWh.  At one kW you would need 60 hours to recharge.  Allowing 12 hours of decent sunlight per day, that would be 5 days.  Doesn't work when you can discharge it in 3 hours.

Yes ...

The solar manufacturer Hanergy recently revealed four models of electric cars that incorporate the company's thin-film solar modules into the bodies of the vehicles, allowing them to be "zero charge" cars, at least for short and medium length journeys. Hanergy Holding Group, which is a leading thin-film solar company, unveiled its solar-powered concept cars in Beijing on July 2nd, and said that these vehicles could be commercialized as soon as three years from now.

Hanergy's thin-film solar achievements are already at the bleeding edge of solar efficiency, with the company's gallium arsenide (GaAs) dual-junction solar cells recently hitting a record conversion rate of 31.6%, and by covering the bodies of these concept electric cars with its thin-film solar modules, the company hopes to bypass "the bottleneck of poor practicality of previous solar-powered vehicles."

According to Hanergy, the thin-film solar cells on the electric cars are able to generate 8 to 10 kWh of electricity daily from exposure to "five to six hours of sunlight," which can power the vehicles about 80 kilometers (~50 miles) per day, without needing to plug in to a charger at all. The solar cells cover between 3.5 and 7.5 square meters of the vehicles, depending on the model, and the vehicles incorporate "ultrasonic cleaning technology for maintenance of the solar cells."


https://www.treehugger.com/cars/hanergys-solar-powered-electric-cars-can-charge-themselves.html

Playing devil's advocate. Gallium Arsenide is carcinogenic if inhaled. What happens to the contents of these panels in a crash? How would they be recycled at the end of the vehicle's life?

Fretwired

boogieman said:

Playing devil's advocate. Gallium Arsenide is carcinogenic if inhaled. What happens to the contents of these panels in a crash? How would they be recycled at the end of the vehicle's life?

Good points - no idea. However, I would imagine that tech will evolve so every panel and bit of glass on an electric car will collect solar energy to recharge the car. In sunny places like California I bet there are tech firms working on this right now.

Fretwired

Check this out .. a solar powered car ..

https://www.treehugger.com/cars/lightyear-solar-electric-car-claims-500-mile-range-charge.html

crunchman

exocet said:

crunchman said:

Fretwired said:

Electric will work in sunny California (cars will be able to charge using solar energy as they drive or are stationery)

No.

Good sunlight is about 1000W (1kW) per square meter.  Let's say you have 2m x 2m on top of the car where you can mount panels that's 4m2 so 4kW of sunlight.  Even if we allow for really good solar panels with an efficiency of 25% (better than anything on the market now) you would only generate 1kW of electricity.  I think the current Tesla has a battery of 60kWh.  At one kW you would need 60 hours to recharge.  Allowing 12 hours of decent sunlight per day, that would be 5 days.  Doesn't work when you can discharge it in 3 hours.

1KW / sq m?

I thought that it was in the region of 200 watts and that with current efficiency we get 120 - 150 watts max?

It's around 1000W.  I've found 3 or 4 sites that say that.  The best panels currently on the market are around 22% efficiency, but 15% is more typical which would give the 150W that you have heard.

@Fretwired - any idea on the cost of those Hanergy cars?  I suspect they will not be cheap - at least not in the next 15 years.  Also, how durable are they, and how much would it cost to replace a wing or a bonnet in the event of a prang?

Fretwired

crunchman said:

It's around 1000W.  I've found 3 or 4 sites that say that.  The best panels currently on the market are around 22% efficiency, but 15% is more typical which would give the 150W that you have heard.

@Fretwired - any idea on the cost of those Hanergy cars?  I suspect they will not be cheap - at least not in the next 15 years.  Also, how durable are they, and how much would it cost to replace a wing or a bonnet in the event of a prang?

Solar powered cars are expensive - the Dutch car is about £116K which makes it a non-starter at the moment. When the tech is proven and goes mainstream the costs will plummet. What I do know is there are new materials capable of trapping solar power. I just had my roof retiled and the roofer was telling me of new tiles that look like conventional roof tiles yet collect solar power, so no more horrible shiny panels.

I suspect that in the future we'll have big batteries in our house to store electricity from solar and wind and take the strain off the National Grid while we're charging our cars outside.

chillidoggy

All these solar-powered cars are going to need a lot of water, you'd have to wash them on a regular basis for maximum efficiency.

exocet

Fretwired said:

crunchman said:

It's around 1000W.  I've found 3 or 4 sites that say that.  The best panels currently on the market are around 22% efficiency, but 15% is more typical which would give the 150W that you have heard.

@Fretwired - any idea on the cost of those Hanergy cars?  I suspect they will not be cheap - at least not in the next 15 years.  Also, how durable are they, and how much would it cost to replace a wing or a bonnet in the event of a prang?

Solar powered cars are expensive - the Dutch car is about £116K which makes it a non-starter at the moment. When the tech is proven and goes mainstream the costs will plummet. What I do know is there are new materials capable of trapping solar power. I just had my roof retiled and the roofer was telling me of new tiles that look like conventional roof tiles yet collect solar power, so no more horrible shiny panels.

I suspect that in the future we'll have big batteries in our house to store electricity from solar and wind and take the strain off the National Grid while we're charging our cars outside.

I stand corrected I was getting confused with the rather poor efficiency (20% max) which is where my 150w / m2 came in.

exocet

Fretwired said:

crunchman said:

It's around 1000W.  I've found 3 or 4 sites that say that.  The best panels currently on the market are around 22% efficiency, but 15% is more typical which would give the 150W that you have heard.

@Fretwired - any idea on the cost of those Hanergy cars?  I suspect they will not be cheap - at least not in the next 15 years.  Also, how durable are they, and how much would it cost to replace a wing or a bonnet in the event of a prang?

Solar powered cars are expensive - the Dutch car is about £116K which makes it a non-starter at the moment. When the tech is proven and goes mainstream the costs will plummet. What I do know is there are new materials capable of trapping solar power. I just had my roof retiled and the roofer was telling me of new tiles that look like conventional roof tiles yet collect solar power, so no more horrible shiny panels.

I suspect that in the future we'll have big batteries in our house to store electricity from solar and wind and take the strain off the National Grid while we're charging our cars outside.

That's what Tesla are doing already, they sell "house batteries" in the U.S now.

crunchman

Batteries in houses make sense.  I wonder if it would make sense to put lower voltage DC wiring in houses.  Most modern electronics will have power supplies that drop them down to a low DC voltage internally.  DC LED bulbs would actually be cheaper than the 240V AC ones we currently have, and probably last longer too as it's normally the stuff that rectifies and drops the voltage that breaks.

Keep 240V in kitchens but it probably wouldn't be needed elsewhere.

Have your solar panels store energy in a battery, and then have a low voltage LED lighting circuit, and low voltage circuits for electronics.  You would save on having to convert DC from the panels to AC and then back again.  It would also be a lot safer if there were less 240V wires running around the house.  With the lower voltages, you could legally do DIY lighting stuff.

Battery capacity that would be enough to charge a car is a whole different level though.

Fretwired

chillidoggy said:

All these solar-powered cars are going to need a lot of water, you'd have to wash them on a regular basis for maximum efficiency.

Just coat them in the stuff they put on airliners to repel water and dirt.

Sporky

crunchman said:

You might need to read up on this.  The quoted range on the Toyota Mirai is 312 miles.  That's close to what you get from most ICE cars.

That's just a hair over half what my car does as real-world range, and it's a lot faster than a Mirai. In practice the Mirai probably does what, 200 miles on a tank? So comparable to a supercar, not a family hatch or repmobile; the word range on my car is over 700 miles.

Hydrogen has low energy density - that's a fact which you "might need to read up on".

LoFi

Sporky said:

Hydrogen has low energy density - that's a fact which you "might need to read up on".

Doesn't that rather depend on the pressure you keep it at?

crunchman

@sporky I only get around 350 miles from my car.

Even if the real world range is only 200 miles rather than 312 miles, that makes a big difference over where battery cars are at the moment.  It would get me to my Grandma's on a single tank.  It would allow me to do a round trip to my parents on a single tank.  No electric car on the market at the moment, or in the near future is likely to let me do that.

You said "Hydrogen cars will only ever do relatively short hops between quick refills."   Even if real world range is 200 miles, that's more than just a short hop.

You are also forgetting that fuel cell cars will improve.  Honda are quoting a 366 mile range for their new fuel cell version of the Clarity.  That's 54 miles more than Toyota are quoting on the Mirai - and definitely not a short hop even if it's only 250 miles in the real world.

In reality, you should be stopping every couple of hundred miles for a break anyway on a long journey.  Filling up at that point isn't a big issue.  At least you won't have to wait an hour and a half for it to charge.

By the way, the speed of your car doesn't rally matter that much.  Even if your car is faster than a Mirai, that's not a lot of use in an everyday situation.  At best you'll be stuck doing something close to the speed limit.  Normally, you'll be stuck in a queue somewhere.

exocet

Sporky said:

crunchman said:

You might need to read up on this.  The quoted range on the Toyota Mirai is 312 miles.  That's close to what you get from most ICE cars.

That's just a hair over half what my car does as real-world range, and it's a lot faster than a Mirai. In practice the Mirai probably does what, 200 miles on a tank? So comparable to a supercar, not a family hatch or repmobile; the word range on my car is over 700 miles.

Hydrogen has low energy density - that's a fact which you "might need to read up on".

Isn't it "just" a case of compressing it more?  I'm sure that's more difficult than it sounds but this source claims that its possible to get very good energy density.

http://www.rebresearch.com/blog/hydrogen-versus-battery-power/

ThePrettyDamned

Sporky said:

crunchman said:

You might need to read up on this.  The quoted range on the Toyota Mirai is 312 miles.  That's close to what you get from most ICE cars.

That's just a hair over half what my car does as real-world range, and it's a lot faster than a Mirai. In practice the Mirai probably does what, 200 miles on a tank? So comparable to a supercar, not a family hatch or repmobile; the word range on my car is over 700 miles.

Hydrogen has low energy density - that's a fact which you "might need to read up on".

I think this is where we need a big culture shift - a move away from speed, and possibly convenience, and into the realms of pure practicality. 

A bigger car will weigh more and thus need more energy. It would have capacity for a bigger battery, but would need longer to charge - so how often do you need, for example, 500 miles from a tank (example, a long round trip)? Some people genuinely need that for carting things around and long journeys (where you need more comfort), others (I suspect even most people) will only *need* that once or twice a year, for which a hire service may suit better. 

More smaller cars may help ease congestion and make parking easier (reduce size of parking spaces - I'm thinking smart car size up to aygo/c1 size cars). It may even make roads safer, giving cyclists more room. More room and safer cycling means more cyclists, means less demand for cars, means more space on the roads... 

Then again, I'm a bit of an eco head and I appreciate there are a lot of practicalities to be taken into account. A travelling consultant would need a car that's more comfortable and capable of long journeys, but I would hazard most people cover no more than 80 miles in a day 95 percent of the time (myself included). 

With regards to shopping, it may be that using delivery vans are more efficient - one fully loaded van could efficiently plan a route and deliver shopping to a good few families, rather than a car per family embarking on the same trip. Not needing mega boot space means a lighter car, less demand for power to move it. 

Basically, it's unrealistic right now but I am of the opinion that over time, we will need a huge rethink of transport solutions, and it may mean less convenience for a few people (although I'd hazard the advantages would outweigh the disadvantages). There is, obviously, also the question as to the impacts on biodiversity and the climate through manufacturing so much stuff. 

There is also the question of product life cycle - how long would people keep it? Is it reasonable to want a new car every year, two years, five years? Lots to think on. 

crunchman

@ThePrettyDamned ; has raised some good points.  Patterns of use will definitely change in the future.

If/when driverless cars go mainstream, a lot of people will stop owning their own cars - especially those who live in cities.

If you look at the price of Uber, and subtract the price of the driver's wages, and allow for reduced running costs in the future because it's using electric motors (whatever the energy source), and allow for not having to pay for parking at the far end, then the cost of taxing, insuring, servicing, resident's parking, and MOT on your own personal car won't be worth it for most people.

You might also make things more efficient by using the correct vehicle.  We have a 7 seater, but the majority of miles are my wife driving to work on her own.  If she did call up a self driving Aygo type thing, and we only used a 7 seater when we needed one, there are big energy efficiencies there.

exocet

crunchman said:

@ThePrettyDamned ; has raised some good points.  Patterns of use will definitely change in the future.

If/when driverless cars go mainstream, a lot of people will stop owning their own cars - especially those who live in cities.

If you look at the price of Uber, and subtract the price of the driver's wages, and allow for reduced running costs in the future because it's using electric motors (whatever the energy source), and allow for not having to pay for parking at the far end, then the cost of taxing, insuring, servicing, resident's parking, and MOT on your own personal car won't be worth it for most people.

You might also make things more efficient by using the correct vehicle.  We have a 7 seater, but the majority of miles are my wife driving to work on her own.  If she did call up a self driving Aygo type thing, and we only used a 7 seater when we needed one, there are big energy efficiencies there.

It all appears to be going in the same direction - "driverless cars" + "electric cars" = Change in Car Ownership model

fields5069

hotpot said:

Fretwired said:

chillidoggy said:

I've long since wondered: Are we just moving emissions from cars to power stations?

Yes. But you have to factor in battery production. I'm not sure electric cars are the answer. How would you charge your car in an average urban environment? The cost of installing charging points would be prohibitive and the UK's whole electrical infrastructure would need a major upgrade. No money - won't happen.

Hydrogen fuel cells could be the answer. You refuel your car as you do now instead of petrol you use hydrogen.

I was watching an episode of 'Fully charged' the other week about turning lamp standards into charging points as the electricity is already there and wouldn't need the pavement digging up.

We're going to need more lampposts!

chillidoggy

fields5069 said:

hotpot said:

Fretwired said:

chillidoggy said:

I've long since wondered: Are we just moving emissions from cars to power stations?

Yes. But you have to factor in battery production. I'm not sure electric cars are the answer. How would you charge your car in an average urban environment? The cost of installing charging points would be prohibitive and the UK's whole electrical infrastructure would need a major upgrade. No money - won't happen.

Hydrogen fuel cells could be the answer. You refuel your car as you do now instead of petrol you use hydrogen.

I was watching an episode of 'Fully charged' the other week about turning lamp standards into charging points as the electricity is already there and wouldn't need the pavement digging up.

We're going to need more lampposts!

Fuck me, it'll be hell up our road, then. It's already 'parking wars' on a daily basis, so access to the two street lamps we have is likely to end up in pitched battles.

Fretwired

chillidoggy said:

Fuck me, it'll be hell up our road, then. It's already 'parking wars' on a daily basis, so access to the two street lamps we have is likely to end up in pitched battles.

Yep, and guess what. Angry householders will pinch the cables or disable the charge point as people from other streets take advantage - vandalism will be rife. And the local kids will have fun as well.