Saturday, February 7, 2009

General: It's Prediction-Time!

It occurred to me today that now I don't do an email newsletter, I haven't made my New Year prediction this year.

Since we are already in February, I think it is appropriate to make a somewhat further-looking prediction than usual.

As you may know Copper is in seriously short supply world-wide. This has led to a lot of thefts of copper cable recently, sometimes attempted thefts of live cables worthy of Darwin Awards.

Simultaneously, our oil reserves are now on the downward side of 'peak-oil' and in any case we can't afford to burn carbon compounds and exacerbate Global Warming.

This inevitably means an ever more serious attempt to replace Internal Combustion Engines in vehicles with Electric Motors and some kind of electrical power storage.

Since putting new batteries in your vehicle every day is right out, a rechargeable power storage system is necessary and recharge-time is clearly a limiting factor if it can't be recharged in a reasonable time.

Eight hours is, in my opinion, the longest duration acceptable for recharging where a vehicle is used to it's maximum range/performance.
A vehicle that can be recharged in eight hours, adopted throughout a country clearly represents a massive load that cannot be easily distributed throughout the working day barring differences in time-zones.
The best that might be achieved is partial recharging whilst at work, but this is during the part of the day that industry makes it's heaviest demands of the power generating and distribution grid already.

With the current generation of electric vehicles, eight hours does indeed seem to be the best achievable recharge time BUT, this is on 110 Volt distribution outlets due to the limitations on maximum current. On 240 Volt outlets, this can be reduced strikingly to two and a half hours!

Once you can achieve a recharge in two and a half hours, you can also have a managed, phased recharge period in three or more 'shifts' to lighten the load on the power grid which saves building extra generating capacity just to recharge Electric Vehicles.

Given that copper house wiring may soon be impractical due to scarcity of copper, we can expect to see other materials used in this role. To achieve the same deliverable currents will require a moderate increase in wire size but to achieve a high enough current delivery for an electric vehicle revolution at 110 Volts would require a much larger diameter of wire and also present additional difficulties over those already present in working with conductors such as Aluminium.

An alternative would be to make ALL domestic 110 Volt mains three-phase, but this would have it's own complications of expensive re-work and materials as well as overcoming perceived safety issues with the higher phase to phase voltages.

For these reasons (Here comes the actual prediction!), I think it is extremely likely that within five years we will be hearing about the necessity of the USA adopting the 240 Volt standard to enable the Electric Vehicle solution to Oil shortages and Greenhouse Gases.

It is possible that in order to handle the recharging loads an even higher voltage could be chosen to reduce the cost of thicker conductors or to try and carry on with Copper conductors but of a lighter gauge. This would cost more in higher performance insulation and there would undoubtedly be a big panic about the safety aspects of voltages that are higher than any currently used. For these reasons I don't think a voltage greater than 240 Volts would be adopted.

Given the irresolute prevarication about switching to Digital TV (as if they will be any more ready in 4 months time), I can only guess what a mess the changeover to 240 Volts will be.

A sample Electric Vehicle (and a rather tasty one at that) with the recharging times documented.

2 comments:

Coyote said...

I wouldn't be surprised if there were capacity problems exposed by a large-scale change to electric vehicles -- including right at the level of residential wiring. But as for voltages, specifically -- not an issue. USA residential power is already 240V -- that's what electric stoves, dryers, and water heaters run on. The 120V used for pretty much everything else (aka 115V, 110V) is created by split-phasing the 240V line -- half the voltage is one side of ground, half the other side, so to speak. So we're already there, voltage-wise, but you'd need to having something like a dryer outlet available for a 240V plug-in vehicle (preferably something easier and safer for repeated mating cycles). A good question might be whether household wiring will have enough current capacity -- a lot of houses are still only 100A service, and probably old places even less. It'll be an issue!

UnderLord said...

Thanks for the info' Coyote. That's the first I've ever heard in 50+ years about the US having any 240V supplies. More study required on my part it seems!