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Bert22306
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CEO
Re: Refueling time is the biggest hurdle for BEVs
Bert22306   12/18/2013 6:12:37 PM
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But I don't just buy into the Tesla propaganda.

The article talks about electrifying transportation as a complete solution. It seems to me totally unrealistic to pretend that "solar panels" will be the answer.

Wilco1
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CEO
Re: Refueling time is the biggest hurdle for BEVs
Wilco1   12/18/2013 6:05:55 PM
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I forgot:

4. Batteries which are swapped out could be used as a capacitor to reduce load on the grid at busy times

5. Most of the power for a charging station can be provided by solar and wind (that's what Tesla is planning for its charging stations). You'd need about 800m^2 of solar panels per 100kW supercharger, while a single Enercon E-126 could supply up to 7.6MW (that's 30 super chargers running 24/7 at typical UK offshore capacity factor of 40%).

Remember this is all technology that exists today. Not some new technology that requires several major breakthroughs to become even feasible, let alone cost effective.

Bert22306
User Rank
CEO
Re: Refueling time is the biggest hurdle for BEVs
Bert22306   12/18/2013 6:05:21 PM
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This is what I'm talking about:

http://www.hydrogencarsnow.com/blog2/index.php/hydrogen-cars/volvo-ev-with-hydrogen-fuel-cell-range-extender-announced/

http://www.plugincars.com/can-fuel-cells-help-battery-ev-market-107168.html

This type of arrangement ends up being at least 2-3 times more efficient than a regular car overall, i.e. through the drivetrain, especially in urban driving. A regular car is, except under ideal conditions, only maybe 18 percent efficient to the drive wheels. A fuel cell car with electric drive train, inclduing the reformer, should be at least 50 percent efficient. Better in urban driving, because fuel cell sare more efficient at low power, apparently.

I see BEVs as being the brute force and not very interesting solution. Even with this purported 30 minute charging time, I can't remember the last time I had to spend 30 minutes in a gas station. And you don;t find a whole lot of supercharge outlets on city streets. So something better is needed.

Bert22306
User Rank
CEO
Re: Refueling time is the biggest hurdle for BEVs
Bert22306   12/18/2013 6:05:17 PM
NO RATINGS
This is what I'm talking about:

http://www.hydrogencarsnow.com/blog2/index.php/hydrogen-cars/volvo-ev-with-hydrogen-fuel-cell-range-extender-announced/

http://www.plugincars.com/can-fuel-cells-help-battery-ev-market-107168.html

This type of arrangement ends up being at least 2-3 times more efficient than a regular car overall, i.e. through the drivetrain, especially in urban driving. A regular car is, except under ideal conditions, only maybe 18 percent efficient to the drive wheels. A fuel cell car with electric drive train, inclduing the reformer, should be at least 50 percent efficient. Better in urban driving, because fuel cell sare more efficient at low power, apparently.

I see BEVs as being the brute force and not very interesting solution. Even with this purported 30 minute charging time, I can't remember the last time I had to spend 30 minutes in a gas station. And you don;t find a whole lot of supercharge outlets on city streets. So something better is needed.

Wilco1
User Rank
CEO
Re: Refueling time is the biggest hurdle for BEVs
Wilco1   12/18/2013 5:47:18 PM
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There is no need to make charging stations as large as a large petrol station. This is because:

1. Using many small charging stations means there will always be one nearby, and less likely to be as busy as pertrol stations at Tesco or Sainsbury's (it's normal to have to wait a few minutes in a queue before you can even start filling up).

2. Some charging stations will offer to swap your battery pack in 90 seconds to get a fresh ~300miles charge for a fee (instead of 150 in 30 minutes)

3. You only need to go to a charging station on very long trips, as you'll typically charge overnight at home or at your office. Cars are parked ~23 hours a day after all!

From my own experience, I'd need a supercharge or battery swap maybe once or twice a year (eg. driving from London to Le Mans in France). All my other trips are either less than 300 miles round trip or are less than 300 miles one way but include an overnight stay.

Using hydrogen, in whatever form, is completely unrealistic today, unlike EV which is a proven commercial technology.

Bert22306
User Rank
CEO
Re: Refueling time is the biggest hurdle for BEVs
Bert22306   12/18/2013 5:17:40 PM
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Let's even assume these Tesla numbers are real, and not some idealised case that usually doesn't pan out in the real world. And let's assume that we want electric vehicles, powered by batteries, to become the norm and not some oddball curiosity.

In any average size gasoline station, either urban/suburban or on interstate freeways, how many have the luxury of "refueling" only 10 cars for each half hour period? If this 300 mile range is real, then the number of EVs "refueled" would have to similar to the number of ICE engine cars refueled.

I haven't done a scientific survey, but surely 10 cars refueled every 5 minutes does not sound out of line for a lot of gasoline stations. So taking your number, that means at least 6 times as much electricity delivered to each charging station, and this during all hours of the day. That's a lot of "streets" of power dedicated to each charging station.

On the other hand, take out the large battery, replace it with a hydroigen reformer and a regular fuel tank, and you won't impact the grid by one iota.

Wilco1
User Rank
CEO
Re: Refueling time is the biggest hurdle for BEVs
Wilco1   12/18/2013 5:04:56 PM
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Bert, the facts are as follows:

1. The Tesla supercharger uses 100kW to add 150miles in 30 minutes to a Model S.

2. So you charge for 30 minutes, then drive for more than 3 hours, not the other way around (getting 50mph on average is a challenge, even on long trips). I don't know many people who drive for more than 3 hours and never stop to take a rest.

3. Super charging 10 cars at the same time is just 1MW and you service 20 cars per hour.

4. 1MW is no issue at all for the local grid - it's equivalent to a street of houses.

5. Just 1000 stations could supply 3 million pure EV cars which drive 23 miles per day, every day (that's the average distance driven per car per day in the UK).

6. 1000 such supercharge stations would use 1GW. That's just 2% of the UK's grid capacity. Existing wind turbines deliver about 10%, so it would be feasible to make most of the EV power renewable by building more wind farms and using pumped storage.

This stuff is really simple if you bother to run the numbers rather than make them up!

Wilco1
User Rank
CEO
Re: Refueling time is the biggest hurdle for BEVs
Wilco1   12/18/2013 4:41:33 PM
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My house has 23kW power connection, which is pretty normal by European standards, so I could recharge a 86kWh battery (300 mile range) in about 4 hours. A recharge point could super charge 10 cars at the same time at 100kW to add 150 miles of charge in 30 minutes (this is what Tesla super chargers do).

Note 1MW for a super charger is not much compared to a modern data center which uses 2.6MW. The UK's datacenters use 2.9GW in total, so adding a few super charger stations should be no issue at all for the grid.

 

 

  

selinz
User Rank
CEO
Re: Refueling time is the biggest hurdle for BEVs
selinz   12/18/2013 3:45:48 PM
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My 6 year old civic hybrid (251K miles) has electric power steering and electric assisted AC. It makes sense. When I'm sitting at light, the electric boost is enough to keep the car cool sitting at a light. But for intial cooling, the engine powered assist is needed for speed. Not sure how they pull all that off but it seems to work nicely... I think the Chevy Volt model is the way to go. You never have to charge it unless you want to...

Bert22306
User Rank
CEO
Re: Refueling time is the biggest hurdle for BEVs
Bert22306   12/17/2013 4:02:01 PM
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bk11, I was only pointing out that in an EV that doesn't include some sort of ICE, the only efficient way of obtaining heating and cooling of the passenger compartment is to use a heat pump. Yes, the reversible A/C units you mention. (And they would also be able to be completely sealed, because there's no need for an external rotating shaft.)

However, the next point is, would this make sense in a regular car? I don't think so. So I was disagreeing that gradual electrification of standard ICE cars, perhaps even most hybrids, necessarily makes a lot of sense.

I don't know what the road blocks are for using the ammonia cycle in regular cars. Could be cost, could be that it takes longer to cool down the interior of a hot car on a summer day. But the ammonia cycle clearly works, and it uses heat from a flame usually.

Frank, thanks. I agree that one can't get away from the fact that quick recharging of batteries will require very large charging power, EVEN with this idea of mechanically swapping the entire battery pack. What do you do with all those discharged batteries? They have to be recharged. We can't just ignore reality.

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