On Mon, 21 May 2007 09:10:35 -0400, Jeff wrote:

* Brian Whatcott wrote, On 5/21/2007 7:44 AM:
On Sun, 20 May 2007 22:44:01 -0400, Wayne.B
wrote:

On Sun, 20 May 2007 05:51:09 +0000, Larry wrote:

at $1500, approximately 1/4 the cost of the usual diesel
genset in this class, you can replace it 4 times to the break-even point,
spreading out your operating cost over many years, not at at the outset.
Here's my take on the numbers.

Let's assume a 1500 hour life which may be optimistic. That means you
are paying $1 per hour for equipment amortization which is more than
20 cents per kwh even if all your fuel is free. Fuel at current
prices would add another 20 or 30 cents.

Generating your own electricity is not cost effective if you can buy
it for 10 cents per kwh.


Let's take another shot at this one.
$1500 for 6kW of electrical power for 1500 hours
AND
6kW PLUS of heating over 1500 hrs
represents a combined heat and power capital cost of
8.3 cents per kWhr
Hence:
Generating your own power and heat can be cost-effective
if you buy power for 10cents/kW.hr

Brian Whatcott Altus OK


If you can get electricity at $0.10/kWh, send some to me. I'll pay
you $0.12! (Our current cost is $0.186.)

There are some obvious problems with this type of analysis - mainly,
the genset is probably happy to deliver at one rate, but the typical
user's rate will vary considerably. And how does the heat factor in?
How much heat can a genset gen? Or are you thinking of reverse
cycle A/C?


If you want a genset to deliver rated power, you can sell to the
utility at their price. Diesels run up to 40% thermal efficiency.
That means that 60% of the thermal energy potential of the fuel goes
into the air. You don't want to extract too much from the exhaust
stack for various reasons, but the warmth of the cooling air is a
freebee.
This is "Combined heat and power" as a newish application already
in use.

Brian Whatcott Altus OK