Diesel vs. propane

[fsck]

I'm looking for case studies on propane vs. diesel costs in a standby power application of 15-25KW.

Obviously, the relative fuel costs will favor diesel, while the initial purchase & lower maint. costs favor propane. At some # of hours/year, the lines cross. My goal is get some numbers to figure out where that point is.

 

[waross]

Strain gauges and weigh the tanks. Used on logging trucks all the time to avoid overloading before driving on weight controlled roads and highways.
An interesting side issue may be the ability to determine the average specific gravity of the diesel fuel.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[wayne440]

Re Plan A- I like diesel fuel. Resupply is less of an issue (55 gallon drum + truck) and it may be easier to find someone that can fix a diesel engine when all the "generator guys" are really busy after a storm etc.

Re Plan B- 3 phase 25kw PTO generators are available, I had one until recently. If your tractor is used regularly, it should run when needed. If not, a neighbor may have one that does. Using the PTO set for home standby, it took about 20 minutes to get the power back on if I was not asleep at the time of the outage. The tractor governor has more droop than is ideal, but the result beat nothing by a large margin.

My "remote tank gauge" was watching the tractor guage over the first tankful, then pouring in 5 gallons every 6 hours thereafter. It isn't a good idea to let the tractor run unattended for long periods anyway.

 

[Fmangas]

Catserveng
You may not have been exposed to the latest automotive style industrial engine. Currently, the NG and propane engine my company produce are EPA compliant. Becoming EPA compliant requires the use of an ECM with closed loop control and active sensor monitoring. We have a number of these units in the NG compression field. Some of these engines are only used at 3 to 6 month intervals when NG prices make it worthwhile.

Personally, I believe a diesel or SI engine would work great it just depends on the any constraints that effect the application.

 

[benta]

fsck, have you looked at turbine powered UPS systems?
It seems they can run on a variety of fuels: diesel, kerosene, propane, natural gas etc.

http://www.capstoneturbine.com/prodsol/products/

No affiliation, but I find their products interesting.

Benta.

 

[JIMGEN]

A Kubota L4400HST is only 45hp. We build PTO that are 160kw three phase so it would not be difficult to find a PTO set that would exceed the power available from the Kubota.

 

[fsck]

I'm SURE you can overload it... In fact the issue I saw looking around was finding a small enough 3-phase one. I didn't see any new 25-30KW ones on my first pass.

He has a Fiat [aka Italian Cat] dozer as well, but it does not have a matching PTO. I was thinking a hydraulic motor might work, but that's another issue.