Re: Nationalized Health Care Preview?

On Aug 4, 3:33 pm, rkshul...@xxxxxxxxxxxxxxxxx wrote:
cryptoguy <treifam...@xxxxxxxxx> wrote:
On Aug 3, 11:49 pm, cryptoguy <treifam...@xxxxxxxxx> wrote:
On Aug 3, 9:50 pm, "Keith F. Lynch" <k...@xxxxxxxxxxxxxx> wrote:

Michael Stemper <mstem...@xxxxxxxxxxxxxxxx> wrote:
"Keith F. Lynch" <k...@xxxxxxxxxxxxxx> writes:
That's surprising.  Power lines tend to be very inefficient.
Inefficient compared to what, exactly?

Compared to other ways of moving energy around -- such as coal trains.

You make the claim, you show the numbers.

I'll add another clip from the Wikipedia article, to save you the work
on the transmission line side:

- start quote -
Long-distance transmission of electricity (thousands of kilometers) is
cheap and efficient, with costs of US$ 0.005 to 0.02 per kilowatt-hour
(compared to annual averaged large producer costs of US$ 0.01 to US$
0.025 per kilowatt-hour, retail rates upwards of US$ 0.10 per kilowatt-
hour, and multiples of retail for instantaneous suppliers at
unpredicted highest demand moments).[13] Thus distant suppliers can be
cheaper than local sources (e.g. New York City buys a lot of
electricity from Canada).

- quote -

So, the number we're after is the cost to move a kilowatt-hour's worth
of electrical power around 300 miles (the distance from the coal
fields to London, plus some slop).

I've already given you the fuel consumption per ton/mile of a freight
train. Look up the efficiencies of a coal powered power station, and
figure out how much coal generates a kilowatt hour of electricity.
Then work out the cost of the diesel fuel to move it 300 miles.

Defend you claim to be a 'highly reliable source'.

Since Keith probably wouldn't do it, I decided to do the arithmetic
myself. Above, I established that the cost to move a KWh of electrical
power by transmission line is in the US$ 0.005 to 0.02 range,
according to Wikipedia.

How much for moving the coal necessary for that KWh by rail?

http://www.miningweekly.com/article/teck-clinches-deals-on-bc-coal-ra...

gives an actual freight coal rate of around $34CDN/t. I'm assuming
this is a metric tonne - 1000 kg. This is to move it only 200 miles,
not 300, but its over more rugged country, so I'll ignore that factor.

The Wikipedia article on coal suggets that it burning coal generates
about 2 KWh of electricity per kg. Therefore, 500g for 1 KWh.

This is 0.0005 tonne, which would cost 0.017 $CDN to ship. At the time
the US:CDN rate was 1:1.16, giving a US$ cost of 0.0147.

So, here's the bottom line

Transmission line cost: 0.005 to 0.020 $/KWh
Railway shipping cost:  0.0147 $/KWh (for this actual example).

Will Keith stand by his claim that transmission lines are "very
inefficient" compared to shipping coal by train, followed by local
generation? I'd say they're on a par, at worst.

To be fair you have to define what you mean by "efficiency". It looks
like long distance electrical transmission is economical from a cost
standpoint, but Keith may mean from an energy efficiency standpoint.

Diesel fuel has an energy content of about 139,000 btu/gallon, so energy
efficiency is about 139,000 btu/gallon / 436 ton-mile/gallon equals
319 btu/ton-mile.

500 g/kWh =~ 1814 kWh/(short) ton =~ 6.191 million btu/ton

Energy loss on the train is then 319 btu/ton-mile / 6.191 million
btu/ton = .005% per mile, or about .5% for a 100-mile trip.

Transmission loss is harder to quantify... One paper(1) gave losses in
100 miles of between about 1% (500 MW @ 500kV) and 8% (2000 MW @ 345 kV)

That makes the train between 2 and 16 times more energy efficient than
the transmission lines.

Of course that doesn't say anything about cost... economies of scale in
plant construction and operation can (and do) easily overwhelm energy
efficiency in the resulting cost.

This also leaves out the fact that putting generated power into the
transmission lines has little costs, either of efficiency or cost,
while
moving coal to the train, and from it to the power station, carries a
more significant cost in efficiency, costs, and added
infrastructures.

Andre
.

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