Backup generators. [RE-wrenches]

[Joel Davidson]

All hydrocarbon combustion is bad for the environment and toxic to humans and
other organisms. More combustion is worse. Less is better. None is best.

7% of propane is consumed in transporting and distributing the gas so over 90%
of propane’s original energy reaches the end user, but propane is not the
perfect fuel. 59% of propane comes from natural gas processing and 41% from
crude oil, both non-renewable.

Here's some information about a diesel/PV hybrid job Ron LaPlace did in the
mid-1980s. The Tarryall Resort, located on the shores of Catherine Lake 25 miles
north of Kenora, Ontario (latitude 50 degrees N) is approximately three miles
from the nearest utility. Cost to run in a power line was well over $80,000.
Typically, residences and resorts there get their power from on-site diesel
generators. These generators last 7 to 10 years. To provide for peak loads, the
generator has to be relatively large, in this case 7.5 kW. A 3-kW back-up
generator is also on-site. Most of the time, though, much less power is needed.
In fact, using 39 kWh per day, the generator was consuming fuel continuously
while supplying an average of 22% of its potential rated output.

By installing a hybrid system, the generator operating time was significantly
reduced. Now, while running, the generator charges batteries and has a greater
load which more efficiently utilizes fuel. Battery power can then be quietly
consumed. A 564-watt PV array further reduces generator running time and
provides a finish charge that greatly enhances battery life. (I don't have
battery bank specifics but I think it was 10 kWh.)

In the first month of operation, the hybrid system's average daily power
consumption was 33.6 kWh. The consumption reduction is the result of Ron's
suggestions for energy conservation. Before PV/hybrid, the generator ran 24
hours a day. Now the generator runs 27.2 hours per week, or an average of 3.9
hours per day. In U.S. dollars, the full value of this $35,500 PV/hybrid system
has a projected pay-back period of less than 5.3 years. (and people think PV is
expensive now!)

Before PV
Annual Fuel cost
at 1.7 liters/hour at $0.2625/liter
$0.4462 X 8760 hours = $3909 annually
Maintenance
oil change every 200 hours
44 changes at $17.50 each = $770 annually
Major overhaul and repair
$3150 every third year = $1050 annually
Generator depreciation
replacement every 8 years = $656 annually
Yearly operating cost = $6385

After PV
Annual Fuel cost
at 2.3 liters/hour at $0.2625/liter
$0.6037 X 1560 hours = $941 annually
Maintenance
8 oil changes = $140 annually
Major overhaul and repair
every 15 years = $210 annually
Generator depreciation
30 years = $175 annually
Battery depreciation
15 years = $560
Yearly operating cost = $2026

(Remember - these are 1986 numbers.)


Carl Emerson wrote:

> Hullo There..
>
> While I can see this topic becoming a good thread, is there an answer to the
> original question ??
>
> Does anyone know of a study done on the pro's and con's of Petrol vs. Diesel
> vs. LPG or natural gas backup generators. I need to consider initial cost,
> economy, maintenance, environmental, reliability etc.
>
> Or maybe no such study has been done ?
>
> Carl Emerson
>
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