Who killed the electric grid? Fast-charging electric cars

Charging electric cars with off-peak power is a fantasy.

Fast recharging times generate lots of excitement, but what seems to be forgotten is that they can lead to a fabulous amount of peak demand.

If you charge an electric car with a battery capacity of 25 kWh during 8 hours, it needs a power output of 3,125 watts. If you charge the same car in just 10 minutes, it needs a power output of 155,000 watts.

Motor art courtesy of  Paul Loughridge. All rights reserved.

How many extra power plants do we need to build if we introduce electric cars on a large scale? According to ecotech advocates, that matter is solved: (almost) none. Electric vehicles can be charged at night. Many power plants have a surplus of energy during the night ("off-peak production capacity") because demand is low and generators keep spinning. Therefore, if we all start driving electric cars, oil consumption will plummet to zero and electricity production will remain the same.

In December 2006, a study at the US Pacific Northwest National Laboratory found that off-peak electricity production and transmission capacity could fuel 84 percent of the country's 220 million cars, if they would be converted to plug-in hybrids. In June 2007, another study from the US government concluded that 73 percent of the existing US light-duty vehicle fleet (cars, SUV's, pickup trucks, vans) could be powered with available off-peak electric capacity if transformed to plug-in hybrids. In March 2008, a study from Oak Ridge National Laboratory said that if 25 percent of the US fleet would be replaced by plug-in hybrids, only zero to eight new large power plants would have to be built if all these cars plugged in after 10 pm.

Plug-in hybrids versus electric

The first difficulty is that these studies talk about plug-in hybrids, not electric cars, which does not stop the media from presenting this research with headlines like "US power grid can fuel 180 million electric cars" or "Electric cars will not need new electric power plants".

Plug-in hybrids have (or will have, because they are not on the market yet) smaller batteries than fully electric cars: a battery capacity of 5 to 25 kWh, compared to 10 to 50 kWh for a fully electric car (source). Plug-in hybrids have both an electric motor and a gasoline engine (which kicks in at distances longer than 40 or 50 miles).

Charging at night?

Electric cars, however, do not have the backup of a gasoline engine and an infrastructure of petrol stations for longer distances.  If we can only charge them at night, the range of our vehicles would be limited to 100 miles (160km) per day, or only half of that when the cars are driven at high speed. There are some electric cars that have better mileage: 220 miles for the Tesla Roadster and 150 for the Mini E - but both have no back seat since that space is taken by the larger battery.

The standard answer to this drawback is that the average commute in the US is only 33 miles, so in most cases the limited mileage of electric cars will be sufficient.

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Manufacturers of electric cars and batteries are pushing faster recharging times  

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Averages are theoretical data: some of us will have to drive only 10 miles per day, others 120 miles. And at least now and then, almost everyone will want to drive longer distances, but that would be completely impossible in this scenario.

Moreover, many people do not have the possibility to charge their vehicles at home - not everybody has a garage. This means that we need an infrastructure of outlets along the curbs of cities and towns if we want everybody to charge at night. Charging electric cars with off-peak electricity might keep the need for new power plants limited, but it is far from practical.

Charging spots

Therefore, it is an illusion to think that all electric cars will be charged at night. A substantial amount of them maybe, but not all. No matter how small the amount of cars that needs charging during the day, it means that we need an intricate infrastructure of charging spots throughout cities and towns.

Companies and governments are already working on that. "Better Place", which announced the building of a charging infrastructure in Israel, Denmark, Portugal and California, is the best known, but there are more.

"Better Place" plans charging spots in parking garages, retail spaces and on street curbs. About 10,000 of them will be installed in 2009 across Israel, and that will increase to 100,000 by 2010, according to Reuters. These spots will be the size of a parking meter and will deliver 3,300 watts (for 1 car) and 6,600 watts (for 2 cars).

This compares to the energy output of 10 plasma televisions (of 340 watts each) to charge one electric car. Adding this load at night might not be a problem, but this becomes a very different story during the day.

1,000 power plants

The study from Oak Ridge National Laboratory also calculated what would happen if all plug-in vehicles would be charged at 5 pm instead of after 10 pm. In this worst-case scenario, the US would need to build 160 "large" power plants (and the related distribution infrastructure, of course). Note: this concerns plug-in hybrids, not fully electric cars, and this concerns a penetration of only 25 percent, not 100 percent.

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Electric motors are more efficient than gasoline engines, but the problem is not total energy consumption, it is peak load

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A complete conversion to plug-in hybrids would thus require 640 extra large power plants. The researchers do not specify what they consider to be a "large" power plant, but this must be around 1,000 megawatts, which boils down to the need for another 640 GW of power plants. That is almost a 65 percent increase of the existing US electricity generation capacity.

Fast recharging time

This is the worst case scenario considered by the researchers, where all drivers plug in their cars at the same time and at the worst possible moment of the day. That will never happen.

Yet, there is another scenario that is much worse and is not considered by the researchers: a fleet of fast-recharging fully electric cars.

A vehicle that needs 6 to 12 hours of charging to drive just 1 or 2 hours will never appeal to the larger part of the public. The automobile stands for freedom of movement, so electric cars will never catch on unless they have at least a similar recharging time to that of a gasoline car (one of the reasons why they disappeared one hundred years ago).

Manufacturers of electric cars and batteries know that, and that is why most of them are pushing faster recharging times. Combined with an elaborate infrastructure of charging spots, this would largely overcome the problem of limited autonomy. We would still need to recharge more often than with a gasoline car, but at least it would be possible to drive further than 100 miles from home, and to leave anytime you want.

150,000 watts

Several manufacturers and researchers have already announced recharging times of 30 minutes or less, which would bring refuelling time quite close to that of a gasoline car. This is only possible through a high-voltage current outlet. Fast recharging times generate lots of excitement, but what seems to be forgotten here is that they come with a price - you have to pump in more energy over a shorter time, which can lead to a fabulous amount of peak power.

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You cannot solve this issue with better batteries - in fact, you can only make it worse

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If you charge an electric car with a battery capacity of 25 kWh during 8 hours, it needs a power output of 3,125 watts (3.1 kilowatts x 8 hours = 25 kWh). If you charge the same car in just 20 minutes, you need a power output of 75,000 watts (75 kilowatts x 0.33 hours = 25 kWh).

This corresponds to the energy output of 220 plasma televisions of 340 watts each. This amount of energy is required over a shorter period, but it has to be available. If you lower the recharging time to 10 minutes, the energy output will be 155,000 watts (155 kilowatts x 0.16 hours = 25 kWh). This equates to 450 plasma televisions.

It will be clear that fast recharging times, even if they are used only by a relatively small amount of drivers, will only be possible with a massive extension of our electricity generation capacity.

Meltdown

There are 220 million private cars in the US. If the complete fleet would be plugged in at the same time it would need 34,000 gigawatts, or 34 times the existing electricity generation capacity of the US. This will never happen, but it compares to "only" a 65 percent increase of the power capacity in the slow-charging scenario above. A large fleet of fast-charging cars will melt the grid.

Charging just 6,500 of these vehicles (0.003 %) simultaneously in 10 minutes will require an energy output comparable to that of one large power plant.

If one in a thousand of these cars (220,000 vehicles or 0.1 %) is charged simultaneously in 10 minutes they will need 34 gigawatts. And one in a 100 cars charged simultaneously will require a total energy output of 340 gigawatts. The question is not how many cars will be charged together on average during the day, but how many of them will be charged together at any possible moment of the day, month or year.

Better batteries?

The energy infrastructure has to be prepared for the highest possible demand - for instance, when everybody wants to drive to a large sporting event. Also, don't forget that someone who wants to make a trip of 500 miles will have to charge the battery 5 times. Because of their shorter range, electric cars need to be refuelled much more often than gasoline cars.

There is no way around this problem. You cannot solve it with better technology - in fact, you can only make it worse. Better batteries with higher capacities may lower the amount of stops at charging spots, but they will raise the amount of peak power required for one charge.

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Electric cars are not refrigerators - but many calculations of their energy requirements treat them as if they were

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The fundamental problem (and we have noted this before) is that electric cars are wireless. Trains, trams (streetcars) and trolleybuses do not have these problems, simply because they do not need a battery. Their energy consumption is spread evenly over their operation time.

People keep saying that electric motors are more efficient than gasoline engines, and that's definitely true, but the problem is not total energy consumption, it is peak load. Electric cars are not refrigerators - but many calculations of their energy requirements treat them as if they were.

Swapping batteries

There is only one last way around the mileage problem of electric cars: swappable batteries (another part of the infrastructure proposed by "Better Place"). This would mean that the batteries could be charged at night at refuelling stations, and thus provide instant off-peak power during the day. There are two problems with this.

Firstly, we are not talking about a handy laptop battery here. The battery packs of electric cars easily weigh 100 to 500 kilograms, which means you will need a machine to get them out and back in again. Moreover, the batteries are not always placed so that you can easily swap them - in many electric cars they are underneath the floor, to optimise weight distribution and centre of gravity.

Secondly, all batteries would have to be the same, and achieving such a standard is both technically and commercially very unlikely. If it doesn't work for laptops or mobile phones, then why should it work for cars? "A Better Place" will make use of standardised vehicles, but the day that we will all be willing to drive the same car, we would probably also not mind leaving the car altogether and - finally - get on a bike, a tram or a train.

© Kris De Decker / edited by Matt Hill / Motor art courtesy of Paul Loughridge.

And finally, another warning from the WorkSafeBC :

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Related articles:

• Electric velomobiles: as fast and comfortable as automobiles, but 80 times more efficient
• Bumper cars on the highway : trolleycars?
• The status quo of electric cars: better batteries, same range
• Overview of early electric automobiles: pictures and specifications
• Trolleybuses and trolleytrucks : get wired (again)
• The velomobile: high-tech bike or low-tech car?
• Wood gas cars : firewood in the fuel tank
• The age of speed : how to cut global fuel consumption by 75 percent, today
• Cars - out of the way : imagine bicycles taking over the motorways
• Leave the algae alone : the second generation of biofuels is set to make things even worse
• Cleantech from the 1940s : the Citroen 2CV
• Magic Motorways : GM propaganda
• Trolley canal boats
• Bike powered electricity generators are not sustainable

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Comments

[Mark Van den Borre]

(1)

I wouldn't underestimate the possibilities of introducing some intelligence into the power grid. I'm sure you must have read stuff like http://en.wikipedia.org/wiki/Smart_grid .

Let's take demand response support as an example. That enables you to order your car to only recharge when it learns from the grid that electricity is cheap.

Mark

[kdd]

(2)

Not compatible with fast recharging times. What's the use of being able to charge your car in 10 minutes if the smart grid tells you to wait 2 hours?

[Tuan Hauptmann]

(3)

Good article. How about a follow up article, looking into what kind of power sources (apart from our dwindling oil), that would be available or under development,to power the electrical power plants? I know such articles are many, but in context with this article, it would be truly thought provoking.

[kdd]

(4)

Thanks. Actually, there are so many problems with the concept of electric cars that you can expect more than one follow-up article to come. Stay tuned!

[Jacob Jay]

(5)

Not withstanding supplying the average load increase, as Mark suggests, a smart grid would surely resolve the issues of peak charging—but every 'consumer' in the grid would have a priority, vehicles would probably need to be fairly highly prioritised to prevent waiting around for the grid to provide energy. (Indeed, you could just pay more for a faster charge if you're impatient, and with smart vehicles trip duration and purpose could be considered too.)

However with or without a smart grid, charging stations with the capacity to store power from a continuous trickle charge (drawing an even load from the grid) with a fast discharge, such as with ultra/supercapacitors, would also reduce sudden draw on the grid and yet still allow vehicles to be charged in much the same time it takes to fill a tank of liquid through a pipe.

[M]

(6)

While I doubt that Mr. Van den Borre's only source is wiki, my first comment has to address the wiki sites. That they appear to be becoming the ultimate reference, is frightening. I am, yet again, so very thankful that I found the independent Low-Tech magazine. And, although there are reference books everywhere in the house, including stacked on the floor, I want to increase their number and range, even though I do not have the intellect to comprehend much of what they offer. What power to be the 'bible' for all knowledge. Dangerous.

As a child, I well recall seeing transportation of the future clips showing a happy Norman Rockwell family playing a board game in their 360 degree-view car which had been placed on a kind of monorail. (There is probably a Wiki article about it). Even though I was under age 8, I was completely taken with the concept. It made perfect sense. No fuel was used -- it was safe -- and people could retain their personal vehicle.

I do not recall what the infrastructure was that gave the car power once it left a major route, but one thing is certain -- we have to be willing to 'wait for the bus' if we want to decrease the use of fuel and other resources. Perhaps board games could be offered as an incentive.

[Roger]

(7)

Get rid of cars period. Change the car dependent paradigm. Imagine a society not needing them.

[Rhamnus]

(8)

Only one thing is clear to me, and that is that no one can give a definitive answer to the problems that the future has in store for us (who are we trying to kid?). At least people are trying to come with new ideas and suggestions as to how to tackle the incoming crisis. To me, the solution will come from a wide range of areas (improving the technology of the electric cars, improving the technology of the electricity production, changing people habits and attitudes to the use of energy, etc, etc, to name but the first three that come to my mind). The current system was not implemented in one 'go', but it evolved over a period of time until it affected most people in this planet. We cannot expect therefore that changing our current system can be done right away leaving the humanity completely un-affected by the change. A crisis is inevitable, and maybe necessary?

[Michael Dowling]

(9)

Okay,Kris,I totally agree with the comment by #5.My idea was flywheel storage to support the heavy current draw at recharge stations,although ultracapacitors would work as well.This would be especially important considering that researchers have discovered a new lithium battery material enabling recharge times measured in seconds: http://www.physorg.com/news156000014.html

[kris de decker]

(10)

I love flywheels so I wanted to know how they look today. Here is one, see the picture on page 2:

http://www.vyconenergy.com/pq/VYCON_VDC_Data.pdf

Full of electronics, weight 829 kg, dimensions of a large refrigerator, a storage capacity of 160 kW. Just enough to charge one car battery of 25kWh in 10 minutes. If 100 cars pass through the "petrol station" daily, you need 100 of these flywheels.

Flywheels could solve the peak demand problem, just as more power plants could solve it, but both are "a massive extension of our electricity infrastructure".

The extra infrastructure required for electric cars could be renewable energy plants and flywheels, or it could be coal plants and another layer of batteries to charge the batteries (as others have proposed). But either way it will cost an awful lot of money, materials, energy and CO2 to build it.

At the expense of greening the existing electricity infrastructure and building better public transport.

Thanks for the link. Charging a laptop battery of 100 Wh in just 10 seconds will require 36,000 watts...

[Retrace]

(11)

Dear 7.
Imagine a society with out cars? Get rid of them? Yeah...why don't we just get rid of people's freedoms too. Lets say, "Person A you may only consume such and such amount of materials and energy. A. You may only live here or there, travel this far....oh and If you say this or that you will be fined. Oh and don't forget to wear your white government provided clothing....No no don't worry it will be a bluish hue next year."

Sincerely,
19382-74

[Adam]

(12)

@11 - I like the idea of anarchy too, but it doesn't fit into a congested world. For instance, I don't think you should be able to own a nuclear bomb. Does this compromise your freedom? Yes. The question becomes, when is it okay to crop freedom? The answer is simple, when allowing one a freedom compromises the collective freedom of the many.

You make it sound like limiting the amount of material a person can consume is some big human rights violation. If there is x supply of material and y people in need of it. This yields an average of x/y materials available to each person. So using more than x/y lowers the amount available for somebody else. Surely you can grasp the idea, that governments are in place to allow its people to decide the methods they invoke for making things as efficient and pleasurable for themselves as possible, by working together and in accordance with majority rules in democracies.

You've heard of laws right? Do they, likewise, make you feel like you live in a numbered system of fascists? All of them? Even the one's that are developed by the majority on behalf of the majority? Even laws against murder and theft?

I really hate this point of view that everybody should get to do whatever the hell they want even if it hoses everybody else over.

[Pangolin]

(13)

I imagine that people in your future will be too stupid to anticipate their travel requirements; how odd. The average daily driver drives less than 40 miles. That is easily within the reach of advanced lead acid batteries such as the Firefly. (http://preview.tinyurl.com/cvv3kg)

The stupid people of the future would also be unable to rent internal combustion engine vehicles for long trips or connect an EV pusher trailer or charger trailer. Of course stopping for coffee or lunch on a midrange run of 120 miles or so while the batteries top off would be out of the question.

That's a dang shame that future people can't figure these things out and thereby benefit from the energy savings and easy maintenance of electric vehicles for their normal, short-range, driving. I bet they're going to be too helpless to use timer switches on charging plugs also. Must be the fluoride in the water.

http://www.jstraubel.com/EVpusher/EVpusher2.htm
http://www.madkatz.com/acpropulsion/longRanger.html

[Doug]

(14)

If we were to deal with the fast charging problem, with charging stations (analogous to gas stations), we could have these charging stations soak power overnight, and emit it as customers come to
"fill up."

That of course leads to the problem of how are the charging stations going to buffer the energy? Capacitors? hydrogen? thermal energy storage? flywheels? batteries? pumping water into storage tanks? I don't know what the best answer to that problem is, but I think it's one that can be tackled.

[Remarksman]

(15)

Let's flash back in time...
Imagine we have oil wells that pump only a certain amount of oil per minute. Oil-powered vehicles pull up to the oil well and want to re-fill their tank. If they don't want to wait for an hour to fill their tank, we're going to have to massively increase the number or size of our oil wells!
Oh, wait, or we could just build a big tank and store the oil.
OK, the demand/load is an interesting concern, but your article seems a little breathlessly stunned.

[kris de decker]

(16)

Odd remark, because that is exactly the problem.

You can store oil in a tank. You cannot do that with electricity.

There exists no (safe, cheap, ecologically friendly, efficient) technology to store large amounts of electricity.

[John]

(17)

Er, of course you can store electricity, in a battery. As it is battery recharging that we are concerned with here, the simple answer is to swap batteries.

Arrive at a recharging station with a flat battery; remove one or more suitcase-sized batteries from the car, perhaps on some robotic trolley; install fully charged batteries; drive off; flat batteries are recharged overnight when the grid is not fully loaded.

The main point is that battery cars have limitations. They are effective for some types of journeys, such as shortish distance commuting, but not suitable for longer journeys. So accept the limitations and change the type of vehicle you use. After all, you maybe already use a bicycle for short trips, a car for longer trips, and when travelling overseas maybe you fly?

[kris de decker]

(18)

As mentioned in the article, John, swapping batteries is not so straightforward as you describe it.

Don't you think it is significant that half of the e-car advocates believe swappable batteries are the obvious answer, while the other half believes the obvious answers are capacitors, hydrogen or flywheels? And both sides are convinced that the other solution won't work. We will have to make a choice, because otherwise the infrastructure costs will be doubled.

What concerns your last point: I am afraid you are saying that, in the future, we all need two cars. An electric car for short distances, and a gasoline car for longer distances.

[John]

(19)

No. Battery swapping, hybrid EVs, fuel cell EVs, range extended battery EVs, pantograph charging and plug-in recharging could all coexist. It would even technically be possible to swap batteries on a fuel cell vehicle, say, after a long, high duty journey. Whether that would ever be necessary depends on the design of the vehicle’s on-board charging system, and the duty required by the driver.

Practical designs for battery swap electric vehicles exist today. Machines to handle the batteries are entirely possible. I can envisage something like a trolley jack. The Lithium Force e-Bus uses a battery swap system using two robots. It is clear that standardisation will be necessary; there are many precedents in the automotive industry for this.

I did not say ‘that, in the future, we all need two cars’. I said ‘change the type of vehicle you use’. This might be a hired car, or a bike, a tram or a train, or a scooter or an aircraft or a boat. Some people might have two cars, as they do today; others will not.

Today we happily accept the paradigm of using appropriate vehicles for different types of journeys, accepting the limitations of each mode of transport. No one expects to own the aircraft, train, tram, bus, taxi or ferry they use. In the future, the dividing lines between the modes might shift, but the principle of changing vehicle will be as it has always been. We will adapt to new vehicles.

[John Powell]

(20)

A hundred years ago you could have easily run a headline saying "Gasoline powered cars a fantasy, no way to build infrastructure to fuel them, roads are bad, etc."

Please - most folks will be content to charge cars slowly either while they are asleep and/or at work. If they need a 10 minute charge they'll pay a premium at a quick charge station, or buy the equipment to store the energy in their garage. Sheesh!

[Kansan]

(21)

Sigh... Still too much focusing on that non-existant one answer solution, when as always the soultion will be multifaceted. The conglomerate of solutions needn't cost the consumer that much. Some corporations and industry may see a temporary reduction in the growth rates of profits. Please note I didn't sat there will be a wholesale failure of business going broke, maybe those who remain insisting in making buggy whips, :) The motor vehicle isn't going anywhere anytime soon, but we all know things can't stay the same. Yes if where able to convert to plug in electric over night, without updating the grid over night, the grid now is service will fail. in the event battery technology improves, one may have multiple batteries set to take advantage of solar and wind electric production when available, so not every one will be charging off the grid at the same time. Has been a very long time since a truely free market existed, when it did it work mostly for the benifit of that few able to control the market, not the public in general. There will be communities where walking and HPV can serve most wellwith little hardsship, there will be communities where the same can't work at all, no matter the hardship. Balance my good citizens.

Laws and regulations brought as all the transportation systems now in place now, and it's unreasonable to not to expect laws and regulation will take use into any forthcoming transportation systems

[Fibb222]

(22)

You mentioned two problems with battery swaps:

Neither of which are a problem.

1) Better Place swaps will be done by a robot and the battery will come out and go in from the bottom of the car - therefore it is as low as possible for better handling and weight distribution.

2) BP won't require that all batteries be the same. The swap station will be able to handle different battery formats. see this interview for more info:
http://www.onpointradio.org/2009/04/shai-agassis-2020-vision

People that criticize the BP batt swap plan, often don't know all they should about it.

[Richard Campbell]

(23)

150 and fifty years ago, the big transportation problem was trying to figure out what to do with all the horse manure. I suspect another problem was growing all the feed to fuel the horses. I'm sure a lot of bright sparks were figuring out all sorts of ways to figure out how to preserve the status quo by finding creative uses for manure. Well, the auto and truck came along transforming the transportation system and the problems with horse-powered transportation went away.

Now 150 years latter, we are facing similar problems. Waste from automobiles creating huge environmental problems and dwindling fuel supplies for automobiles. Like the bright sparks 150 years ago, many people are trying to problem solve and preserve the status quo rather that creating better forms of transportation. I'm sure the reactions were the same 150 years ago. People are in love with their horses.

We have the opportunity to focus our creativity and resources on transforming our transportation system and our world but we have to be willing to let go of the past. Face it. The age of the automobile is over. The solutions are high speed rail, rapid transit, cycling, bike sharing and probably some others that haven't been dreamed up yet. High speed rail is simply better transportation than driving. It is faster, more environmentally sound, more comfortable and safer.

An example of these bad ideas is so called "Better Place"'s battery swapping. People are right that most trips are short so people won't need to swap for everyday trips. They will need to swap for longer distance trips. Only problem, people usually want to make these long trips all at once. Long weekends for example" So, a company is going to maintain a huge inventory of $5000 batteries and build thousands of swapping stations with the storage for these batters that will be only used a few times a year.

Even worse, while claiming a range of 100 miles for batteries, this will only be true for low speed trips in an unloaded car with only the driver. Put 5 people and their luggage in a car and travel at highway speeds with air conditioning on, the range will plummet to likely less than 60 miles. Are people going to be willing to stop every hour for batteries and wait in line ups for everyone else who wants to swap batteries? Not likely. And is "Better Place" going to wait until night to charge those batteries? Probably not. They will want to charge them right way so their inventory of costly batteries that will likely be quickly obsolete due to advances in technology can be smaller.

The great thing about high speed rail for long trips, is it solves the range problems with electric cars. Instead of trying to design complicated and unworkable non-solutions to make electric cars for long range trips, use rail for the long range trips instead. Then use small neighbourhood electric vehicles for what they are good for. Short trips around the city. Since they won't have to survive high speed collisions, they can be very light weight.

Please realize that we need solutions that work practically on a large scale and realize that people want better solutions, not expensive non-solutions that are less convenient and not workable.

[DanFoster]

(24)

There are technologies that will fix this problem eventually. Specifically I believe that capacitor technologies will exist. A capacitor could be constantly charged at a few thousand watts 24 hours a day, until it is full.

Then when you need to reload your car, you plug into the cap and draw the power at 100,000W or more. Then the capacitor slowly recharges again.

This is a concept that petrol stations should be seriously considering. It would likly be much cheaper for the petrol stations to house massive capacitors/banks that are slowly recharged from the grid constantly, than for everyone to have their own. They could allow people to drive in their car and recharge their batteries at very high power, very quickly. The more capacitors you have the move electricity builds up, and the charge can stay as lone as possible, so there is no energy waste problem. Indeed if cars themselves end up running off new technology capacitors this is probably how it will be done, but quickly move energy from one capacitor to the next.

[Jim]

(25)

I'm not sure about the latest battery technology but fast charges typically reduce the service life of batteries because of the higher heat generated during a fast recharge.

Also, a question. Has someone produced an efficiency study for the total energy required to produce a unit of energy for all of the popular energy 'sources'? For instance what is the efficiency of delivering a joule of electricity from source to the wheels of a car? This would include origin generator losses, transmission losses and car motor losses. I'd like to see the same for hydrogen, gasoline and diesel. In short, how much total energy is required to produce a joule work at the end product.

It seems to me that delivering electrical energy over a grid has a lot of losses. Right now hydrogen production requires another form of energy production. Hydrogen is merely another form of a battery or capacitor. Gasoline and diesel require transportation, storage and refining along with thermal losses when it is used.

[davea0511]

(26)

I've thought a lot about this. Quick charging cars are a pipe dream. Electric cars will charge overnight, and maybe in commercial garages. It will eventually increase the cost of electricity at night, but it will still be cheaper than petroleum, so long as we make the investments right now that we need to make. And this is another reason fuel assisted EV's (EREVs) will be here for decades long after the pure fossil fuel car is history.

[Paul Stephens]

(27)

Of course, this article doesn't consider the correct strategy, which is to greatly reduce the number of private automobiles by building a public transportation system (including dispatchable vans and cheap taxis)which makes private ownership of automobiles unnecessary for most of the population. Without the massive waste of petroleum we experience, now (as well as the waste of half or more of existing electrical generation through inefficient homes and appliances), we could easily reduce our petroleum imports to zero, and probably reduce the on-grid generating capacity, as well - phasing out coal and nuclear in 10 years or so. Every electric car could be supplied with a solar panel or small wind generator (using the vented cylinder technology rather than bladed windmills) so that re-charging is mostly off-grid.
Those are all directions we need to take, anyway. It's no longer a matter of "consumer choice" whether or not we quit burning fossil fuels.

[Perry Staltor]

(28)

I hope you apply the same logic to on-demand electric water heating. In fact, that should be your first aim.

There are a lot more people washing clothes, dishes and themselves than driving electric cars. Making the switch from tanks to on-demand systems -- simply to save the estimated 30% radiant heat losses inherent to tanks -- will crash the grid a lot faster than the slow adoption of battery-electric cars.

[Viktor Kovacs]

(29)

When there are multiple options and ways to do something, then a modular system could give very good results. A simple electric car with a modular energy storage system would work for everyone. The car itself only contains the electric motors. The power source could be made replacable. The possible options are: batteries, supercapacitors, on board generators (a diesel motor, a turbogenerator or a stirling engine) and fuel cells. The charging system could use conventional plug-in, fast charging or overhead grid technology, while the generators could be fueled with flammable liquids/gases and for a stirling any heat source would do. A modular system would allow us to pack in only those modules that are needed for the trip. (for example generators are not needed for commute)

Long range travel could be solved by using auto transport trains, when the cars can travel with the owners. Also in hybrid mode, the cars would not have any range limits. In cities an overhead grid is acceptable, while on highways most cars could operate with generators and holes in the city grid can be bridged with on board electric storage capacitors and/or batteries.

Grid problems could be solved by and intelligent grid with local energy storage capacitor banks. Capacitors have the advantage of being cheap and their performance is not degrading as fast as batteries (a 100 year old airgap cap is as good as it was a 100 years ago).

[Michael Cerkowski]

(30)

I admit to skimming the responses, but I would have expected many people to point to an obvious solution to peak charging of EVs: parking lots and garages with both solar arrays and wind turbines. Did no one else come up with this idea, including the authors? Granted, you wouldn't be able to quick charge many vehicles with this kind of setup, but you could slow charge many commuter vehicles over the course of an average work day, and also give 'top off' charges to people in town for only an hour or two. The 'charging lot' would also have a connection to the grid, but the draw from the grid would not usually come near to the amount of power required by the charging stations.

[GoodCheer]

(31)

I believe this article places far too much emphasis on fast charging during the day. At least in the next couple of decades, the people who will buy EVs are people who have a dedicated parking spot and the ability to install a charge spot. With a charge spot 'at home', 95% or more of charging will be at home, over night. In addition, 65% of households in the US have 2 or more cars, so when daily travel needs exceed the range of your EV, just take the other car! Slowly, charge spots may start to appear where people work, watch movies, etc., but I just don't think they'll be used that much.

The great potential of EVs though, is that, because MOST people will use only a fraction of their battery capacity each day, there will be an enormous surplus storage capacity. If the EVs are "Grid Interactive Vehicles", which is not that complicated and an active area of research by several universities, national labs and OEMs, then far from being a problematic uncontrolled load on the grid, EVs can be a controllable storage resource, and will be able to provide grid stabilization services.

This discussion almost exactly parallels that concerning high penetrations of renewable energy: What do you do with it all when the wind blows, and who's power do you shut off when the wind dies. The answer to both of these questions is: Grid Interactive Vehicles with energy storage. So the punchline is, with just a little bit of communications technology (which is cheap), and some market mechanism to make EV owners want to participate (several of which have been proposed), EVs and renewables can support each other, and each will turn the challenges the other poses into a strength. And far beyond "just" cleaning up personal transportation, EVs will be able to clean up the electricity sector too.

Of course, this is not at all a "Low Tech" solution, so it may not resonate with posters here.

[David]

(32)

Compared with hydro-carbon fuels the energy/volume and energy/storage mass for electricity are terrible. Until the battery similar in size and mass of a fuel tank with the same energy content is standard then I cannot see anything more than a specialised future for electric cars. Off peak electricty would be better put to use producing hydrogen for hydrogen powered vehicles whether IC or fuel cell. Of course one day the micro fusion cell directly converting heat to electricity will solve the problem.

[Myrtonos]

(33)

Modern trolleybuses have auxilery power units. They do have batteries but these are only used when driven away from the wires. There are Dual-Mode buses in Boston and Seattle which can use trolleybus wiring and only genetate their own when driven away from the wires, if buses can do that, why not cars?

[Dan]

(34)

Thank you for this article. I am buying a new car and had considered hybrid vehicles but was skeptical. This article made up my mind. Electric power is great an all but it is just is not ready, not now, and not for foreseeable future. Internal combustion is still the best bet.

[Jonharson]

(35)

"Moreover, the batteries are not always placed so that you can easily swap them - in many electric cars they are underneath the floor, to optimise weight distribution and centre of gravity."

Yes and this is exactly where you want them if you were to design an automatic battery changing platform. Just picture a station akin to a car wash, drive unto platform, lift raise, unlatch the battery, lower it down, chain move the car to the next platform where a similar lift raise the new battery in, or a single platform where the same lift perform both operation with a rail system for the batteries.

To solve the peak energy demand you don't need less tech, but more tech, it really come down to: do i want to use my car right now and pay 10 time to price? or will i only need it in 8 hours time.

The city my brother live has adopted an opt-in system that i found quite interesting in that regard, 2 main factor are factored, the network total demand and outside temperature, if a certain threshold is reached a light turn on in the house indicating a peak demand, during peak hours you pay a 100% (or more, cant recall the exact figures) premium on electricity and outside peak time get a 50% discount. If you are careful you can make sizable saving with the system, but it can also cost you more if you are not. I am surprised this has not caught on anywhere else yet.