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‘Electrification Factor’ in Transportation

'Coolness' & performance serve both the market & green goals
Ali Emadi
12/16/2013 11:10 AM EST

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Bert22306
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Refueling time is the biggest hurdle for BEVs
Bert22306   12/16/2013 9:33:31 PM
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Interesting thoughts. But I don't entirely agree.

On heating and cooling. The air conditioning compressor is a heavy load. The car designer will use whatever the most abundant source of power there is, to run such a heavy load. In EVs, especially battery powered EVs, it makes sense to install a heat pump, both for cooling and for heating. What better choice is there? You have no large excess of waste heat for winter heating, nor do you have any rotating motor with a large excess of unused power for running a compressor-based air conditioning system.

But does it make any sense to install a heat pump in a normal ICE car? I doubt it. In winter, it seems to me that there's enough waste heat in most ICE cars that you don't want to burden the electrical system. Coolness factor or not, I would think. And in summer, my question has always been, why don't regular ICE cars use the ammonia cycle for air conditioning? Using the waste heat from the exhaust system? Makes more sense than electrification, in an ICE car, doesn't it? My guess is cost. Either way, though, I don't see that electrifying the heating system makes a lot of sense in an ICE car.

One real problem I have with BEVs is, it takes longer to refuel them than the time you can drive them. Think about it. Drive a car, say, one hour, then you're forced to wait anywhere from 4 to 12 hours to get it refueled. Doesn't sound like something you can brainwash anyone to love, other than the true fanatic. At best, this might work for that second "commuter car," but it hardly supports a model of complete electrification. So we need something better, but also something that doesn't require recharging stations to have their own nuclear power plant, to supply that gigamps recharge current capacity that would be needed, to refuel all those hungry BEVs in a couple of minutes.

Seems to me that a hybrid approach will work best in the foreseeable future, although I would hope the hybrid is not with an ICE. My favorite being, a hybrid EV where the main energy supply is still a hydrocarbon fuel, sent to a hydrogen reformer, then to a fuel cell. And a hybrid-sized battery to take care of those short spurts of power cars need, and also to use regenerative braking for better urban fuel economy.

prabhakar_deosthali
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Battery power is limited
prabhakar_deosthali   12/17/2013 1:28:55 AM
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The passenger car industry is some centuries old and there are many hydraulic , pneumatic and mechanical systems which are proven systems for their simplicity, reliability ,durability and ease of maintenance.

If we are to replace all these systems by electrical systems , first question arise is how reliable they will be compared to the conventional solutions.

Secondly just to replace the engine with electrical motor and the associated batteries, we get only a limited range in one charge. Imagine if all the axillary systems are also to run on battery - what will happen to the range?

AZskibum
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Re: Refueling time is the biggest hurdle for BEVs
AZskibum   12/17/2013 10:09:37 AM
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Excellent points Bert, and especially your tongue in cheek comment about recharging stations requiring their own nuclear power plant to deliver all the current that would be required to quickly recharge multiple BEVs.

Battery R&D will soon lead to commercialization of new anodes that can dramatically increase the capacity of Li ion batteries, but quick charging will require chargers that can deliver currents approaching the "C" rating of the battery. As battery C ratings increase, so does the need for chargers with incredibly high current capability.

Hyperbole aside ("gigamps" is a word you don't hear often!), rapid charging of next-generation EV batteries will require chargers capable of providing tens of kilowatts to each EV. A station that can accommodate a dozen vehicles at a time would easily exceed 100 kW. Nobody is making EV chargers anywhere close to those kinds of numbers, nor are grid infrastructure improvements being made to deliver that level of power to large numbers of charging stations.

The BEV recharging model seems hopelessly stuck in the mindset of 4-6 hours or longer charging times, and the power available from chargers will continue to be the limiting factor, far more so than the batteries. 

bk11
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Re: Refueling time is the biggest hurdle for BEVs
bk11   12/17/2013 1:00:22 PM
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Bert,

What type of heat pump are you referring to?  I thought most larger systems used a compressor, and are essentially just "reversable" AC units.  Did you mean Peltier devices?  I wouldn't think they are nearly as efficient for cooling, but I could see them being used for heat (more efficient than resistive heating.)  I would think they would be pricey in that size, though.

Interesting idea about ammonia cycle for ICE-based cars, though.  I wonder what the roadblocks would be?

Bert22306
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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.

selinz
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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...

Wilco1
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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.

 

 

  

Wilco1
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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!

Bert22306
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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
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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.

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