VtoG

Interesting article in the FT today.

Vehicle to Grid. Basically charge your BEV up off peak, and sell it back to the grid ON peak.

An idea we discussed about a year ago..

I'd be happy just to have the car be an emergency power cut backup for a few days.

With say 50Kwh per car available..and say 100,000 cars..that's 5GW hour..enough to keep the country running for almost 6 minutes. When the lights go out ;-)

With a million cars, it's a whole hour!

Still that's better than Dinorwig. a mere 10GWh IIRC.

Reply to
The Natural Philosopher
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And then a million electric cars off the road with flattened batteries... hmmm, maybe not such a bad idea after all.

Reply to
Ian White

Makes more sense to have power packs in the house to act as a reserve.

25 million homes would keep the lights on for a whole day :-)

Using vehicles as a backup power supply is more an exercise of a solution looking for a problem to solve.

Like in ...it's a bit expensive putting in all the charging points for electric vehicles and the vehicles themselves cost an arm and a leg.....hang on, we could justify this by using them as a short term power buffer for alternative energy sources such as wind power....

It also tends to ignore the issue that electric cars are a middle class solution at the moment - people who have homes where they can easily connect their electric vehicles to their home supply. It is a major infrastructure commitment to install charging points in public areas where all the people who can't park on their own property (think tower blocks, virtually all new housing developments, most inner city areas) can easily and securely pay for their vehicles to be recharged. How many cars are parked on the street or on open car parks?

As opposed to (not that I am stating this is economically viable) deciding that the best way to buffer wind power is to equip homes with power stores (which will always be online) and also encourage homes to install photovoltaic cells to charge the energy store and export to the grid.

Of course, the best solution may be bulk storage somewhere in the grid. Whatever happened to the reservoirs that were pumped full of water and then used to drive turbines when demand was high? It would have to be a massive solution to store more than one day's worth of power.

So perhaps we should be looking at the cheapest way to buffer alternative power generation, not looking at a desire to justify electric cars by tacking on functionality which is not part of their primary design aim.

I suspect that equiping homes with enery stores may be significantly cheaper than installing external charging points.

Cheers

Dave R

Reply to
David WE Roberts

Some PC idea gone mad. If this is truly an economical method, the power companies would do it already and cut out the middle man. Charging *any* battery then discharging it isn't an efficient way to store energy.

Given their cost wouldn't a generator make more sense?

Reply to
Dave Plowman (News)

Some businesses use the main incoming electricity supply to drive a large motor, the motor is connected to a large flywheel and then a generator. This gives them an independant electric supply, resistant to brown outs, surges etc. There is usually a diesel engine that can also be used in lieu of incoming mains to drive the flywheel/generator, it is auto started on failure of the mains, the flywheel providing enough mass so as to smooth out any fluctuations that would otherwise occur, seems to me like a fairly effecive method as there is no interruption between mains failure and diesel engine achieving running speed, as there is with some standby generator setups(these also usually only supply critical systems and are not really suitable for long term use, whereas in the example above, you have everything available to you, so in a manufacturing exammple, production can continue.

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Reply to
Vernon

well actually it dees make sense. The calculations quoted in the FT were about $3000 to install the two way charging kit and a likely $1500 a year income from buying electricity and selling it back to the grid.

Of course if everyone did it, the on peak price would drop.. ;-)

Any solution is better than no solution. I am guessing that on street charging would be no more expensive that all the cameras, speed humps, road signage, parking meters blah blah. If done over a period of a decade or so.

Photovoltaic is more expensive and does less. But in house storage with even lead acid is actually not that expensive. Typical car battery is

50Ah, so 80 of em is 50Kwh. Probably about 4 grand at that level..

geography and physics is not your friend. DinorWig is a mere 5Gwh

I calculated a lake the size of Loch Ness, 1000 feet deep. Cheaper to build power stations.,

TBH, when you look at te cost of storage versus the cost of capacity, few schemes are cheaper. Dinorwig was, but its peculiarly suitable.

General cost of construction of a Nuke is about £1500-£2000 per Kw. BUT it has a 50 year lifespan.

The point to make is opportunity cost: If you buy a battery in an electric car, why not make money out of it?

mixtures.

Reply to
The Natural Philosopher

well its more efficient than DinorWig.

battery turn round including inverters at modest currents is better than

85%-95%

the point you make is not valid though: its not worth doing as a standalone solution, but in terms of having the car anyway, it means you can actually make a bit of money off its battery.

Even if its just special metering that only allows you to CHARGE when demand is low, its still a cost saver and helps smooth demand.

Seriously dave, a car with about 50bhp that did 150 miles on a charge would fit perfectly with my current lifestyle. about 74% of the mileage seems to be the 1.5 mile trip to the village shop and back almost every day.

car engine never warms up. Electric ideal. Most of the rest is a weakly visit to the supermarket 10 miles away.

If a car like that existed for less than ten grand I'd probably have it already.

Reply to
The Natural Philosopher

Technology must have come on a lot in the last 20 years.

When I worked at a computer centre there were 'MA Sets' much as you describe to smooth out fluctuations in the mains supply as the computers were very sensitive to small voltage changes.

However although they were huge there certainly was not enough energy stored in the flywheel to maintain full current demand for the period between the mains going off and the standby generator firing up and coming up to full speed.

Someone who does hard sums might be able to calculate how much stored energy would be needed to power a generator for 30 seconds to a minute whilst the standby fires up (tons of flywheel per kilowatt or some such thing).

I have only once seen a standby generator fire up in anger (in the late '70s/early '80s) - there was a loud bang and a huge cloud of smoke. I thought someone had blown up the computer centre!

Reply to
David WE Roberts

As soon as the market develope there will be no "off peak" since the night time will be the peak charging time whilst the vehicle is in you garage.

MBQ

Reply to
Man at B&Q

Normally the standby generator has to come up to speed and then stabilise the output before coming online, in this instance the diesel set was simply driving a gearbox connected to the flywheel, I am not sure what the response time was, it might be that very sensitive equipment also had UPS backup, it was a high tech factory though.

Reply to
Vernon

Ah yes thats the problem, they do exist but cost an arm and a leg, manufacturers cite low demand as an excuse for high prices. Perhaps the government could spend some money investing in electric vehicles and maybe produce an affordable one to compete with the mainstream manufacturers who will undoubtedly drag their heels introducing affordable technology (similar to BT with broadband). If all it did was accelerate the introduction of affordable (

Reply to
Vernon

Isn't there also the issue of battery life, how many deep discharge cycles before the battery pack needs replacing, I suspect the battery pack will cost more than the potential gains in selling power to the grid.

Reply to
Vernon

which I pointed out earlier..;-)

Reply to
The Natural Philosopher

Discussing the probability of electric vehicles with my neighbour he mentioned that when he worked 'Up north' in the 1960s there were plug in points where cars were parked, while at work, to plug in the engine block heaters for their cars. And possibly the odd battery charger. Or otherwise it would be very hard/impossible to restart the vehicle. Back at the barrack blocks/apartments and/or company housing there were similar arrangements. Diesel construction machinery was left running continuously. These days my neighbour who owns and drives an '18 Wheeler' as an owner/operator occasionally plugs in the 1500 watt block heater to his Cummins diesel. If/when the temperature is below zero Celsius.

So the idea of 'BEV' recharging (on a slightly larger scale) sounds completely possible.

Quote from previous posting this thread: "It also tends to ignore the issue that electric cars are a middle class solution at the moment - people who have homes where they can easily connect their electric vehicles to their home supply. It is a major infrastructure commitment to install charging points in public areas where all the people who can't park on their own property (think tower blocks, virtually all new housing developments, most inner city areas) can easily and securely pay for their vehicles to be recharged. How many cars are parked on the street or on open car parks?"

Reply to
terry

Pah!.Vehicle power feedback is an engineering non-starter. Much better just to run up a good quality flywheel.

50GWhour storage would need a system weighing something like 500 tons (tonnes). Highly efficient and extremely reliable. This equates to something the size of a football field, so could be sited anywhere.
Reply to
john

In a few months the government introduces a Feed In Tarrif (FIT) scheme..

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upto 41p a unit (from small PV systems).

Reply to
Cwatters

That would ensure they never ever became viable for sure ;-)

and

I think the sub £10K electric 'shopping trolley' (as it were), is less than 18 months away.

Think Fiat E-Panda. By keeping the power low, the battery isn't so expensive, and the charger can be a simple 13A one.

at retail levels small (100Wh) lithium batteries are a dollar a watt hour..so assuming you can get 200 charge cycles out of one (conservative really) and you get 100 miles out of 20Kwh..

..£20k for the battery and charging at 10p a Kwh 10x200x50 anpother £1k for electricity..

So £21k to do 20,000 miles. That's what I could so right now with commercially available 'hobby' bits. It too high. But it shows you where the salient costs are: the battery.

Reply to
The Natural Philosopher

that's the rub: see earlier post. However deep discharge cycles are not necessary: for a typical battery discharging over 2-3 hours is relatively soft discharge: likewise how deep it goes is a function of the protection circuitry in the car. (or the battery)

Reply to
The Natural Philosopher

TNP, very interesting comments. re "the car be an emergency power cut backup for a few days. "

something very simple for your requirements,

I note an inverter in eBay, Item number: 290342962113 Plugs into cigar socket of car (12v) with a mains socket providing

240V @175 Watts Unsure of efficiency of conversion , but quite neat for only =A317.

Lyndsay

Reply to
Lyn

Running at 30,000 RPM perhaps?

I am sure if it were that simple, we wouldn't have built Dinorwig.

Let's assume that the power is concentrated at the rim. And all the energy bringing it to a stop can be usefully extracted... 50Gwh is

1.8x10^14 joules, and we divide that by your 500,000 kg - 5x10^5 to get a velocity squared of 360 million meters per second squared.

so as near as damn it 19,000 meters per second. 19 kilometers a second.

68305 km/h.

So yes, 50Gwh is a 500 tonne mass travelling at 68,000 km/h.

Comfortably above escape velocity. Have to be in a vaccuum, and god help us if anything goes wrong. I'd rather be at Chernobyl frankly.

Let's see what the stress on the flywheel will be..let's say the radius is 50 meters so it will have to be doing 68305000/50 radians/hour

I make that about 140,000 RPM.

And the acceleration at the rim is something like a million G.

Simples!

Prat. I hope IJ consulting is not doing any sort of technical consulting.

Or are yu Gordon Brown and I claim my £5..?

Reply to
The Natural Philosopher

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