Diesel Versus Propane for Emergency Power Generation for Water Supply

This sounds more like a discussion you should have with your engineer. Diesel fuel will certainly provide more backup time than propane with equivalent size tanks, even if the propane is liquefied. If you are not sure of the cost to benefit of this engineer's proposal it sounds to me that you should get another real bid from another engineering firm for this town project. Cost speculations from people who do not make formal contract bids can make much more grief for you than help.

Cost is marginal either way. Is there danger in storing diesel fuel over the town's water supply? Is one more dangerous than the other? Explosions? Car running off the road into the building? Seems as though you have avoided my original questions.

What about space junk or meteor impact?

On a more serious note, there are dangers in anything and everything that people do. The question should not be are there dangers of each approach but how does one mitigate each danger. If your engineer is not mitigating the dangers of each approach then regardless of the cost, it would be negligent to use this engineer's design.

You must remember though that this is an international discussion site. From the comfort of my home here on Long Island NY, I cannot tell if your town resides in the Serengeti plains of Africa, the tropical rainforest of Borneo, the tundra outside of Vladivostok or (heaven forbid) you are my town supervisor. (Fortunately for me, Long Island resides on one of the largest water aquifers and has for a long time been using solely well water. So you are not my town supervisor.) I have no idea about the hydrology of your well or the plans your engineer has proposed to extract this water for your town. I do see that you seem to expect anonymous absolute strangers that know nothing of your situation or the design presented to you to give you advice that will effect your town. This greatly worries me.

Our town lies in a valley in VT. The water supply seems to be an aquifer that lies beneath the whole valley and several towns have tapped into it. It can put out about 1000gal/minute but the system will extract an average of 250 when running and up to 400 if necessary. It is pumped to a storage unit above town and a gravity system is used to feed the pipes. We will be the only town in the state that uses diesel for emergency backup power.

The select board sits on their hands and does whatever the engineer says. While I believe the engineer competent, I allow for human frailty: he is paid by the size of the project and I believe has overengineered other aspects of the project. He didn't know the old well house was built on spongy soil and now the original price to rebuild has grown from $400k to $700k. The soil above the well is clay and I believe the well is about 75' deep.

I am a layman who doesn't want to cost the town money, would like to get an opinion from an engineer for free to possibly save the town money. We are a town of 1900 and have limited resources.

Rather than give me attitude like you are the only person with a brain on this site, just ask me what you need to know to answer my question or not bother if you feel your time is too valuable.

Well you've now been given a collection of opinions on which fuel is better for your town project. As I expected, many people have valid arguments and opinions that support the use of each fuel. Each fuel has it advantages and drawbacks.

One drawback that was missed by our community, that you did ask about, is the added hazard of a leak. A propane leak cannot potentially contaminate the ground water as diesel or gasoline potentially can. It is certainly very easy to mitigate either liquid from reaching the ground with a good design but propane cannot reach the water level itself. However, a propane leak can make a very dangerous hazard. Propane is a flammable gas. So a leak anywhere on the storage container can release all of your backup fuel and at a fairly fast rate. A liquid fuel leak will likely not quickly drain your reserve supply. A common factor that a propane or gasoline leak will have is that both fuels will be very easy to ignite outside of the engine's combustion chamber. Either of these fuels will have concentration levels that will be just flammable or explosive. In contrast, one can drop a lit match into diesel fuel at room temperature and the fuel will extinguish the lit match.

There is no single correct answer which fuel will be best for your town. There are only options with known drawbacks and advantages for each choice. You and those willing members of your town board should discuss which approach will be both cost effective for your town and which risks you are accepting with your choice.

You need to decide what the duty cycle is, how much power you'll need and the cost to operate over time. (Propane has less energy per volume, may be cheaper to operate)

The installation costs won't be much different. Do the math.

You may be having the wrong conversation - 75' is not a well.

1,500 feet is a well. 5,000 is a well.

75 feet a homeowner sinks in the backyard with a do-it-yourself kit.

If it is available the best alternative from an initial cost and ongoing expense would be natural gas just like many home, hospital and industrial emergency generator sets use. Propane and natural gas both are cleaner and there is less chance of contamination. If you have a natural gas system you never have to worry about running out of fuel and the changeover can be set up very easy to start automatically.

Rich Hurd

Dreams are window into the future

If you do not keep the diesel fuel fresh then you may not have a backup system at time of need. In this situation and depending on the history of outages I would go with the propane just for simplicity. If there is a big demand for back up a second propane tank would ease your fears. I have used propane both in vehicles, homes and businesses with no negative issues for many years. You have my two cents worth..

Diesel fuel doesn't need to be kept "Fresh" like gasoline. 20 or 30 year old (and even far older) diesel fuel will work perfectly well as long as its not contaminated.

Consider that diesel provides a nice home for algae and these clog up the fuel filters.

I have experienced this many times on ships that had no regular use.

A centrifuge (many $) can get rid of that. Also Biobor^®, a boron-based algicide (not so many $).

If natural gas is available, it could power both the heater and the emergency genset.

If propane is going to be on hand anyway for the heater, using it also for the genset will avoid the complexity and cost of dual fuel systems.

You might find some sample costs by Googling "propane generators" or similar terms.

If propane is going to be on hand anyway for the heater, using it also for the genset will avoid the complexity and cost of dual fuel systems.

Why not just run the propane exhaust from the genset through a heat exchanger to heat the pump house and let a given volume of fuel serve both purposes?

Excellent strategy if the genset were running continuously, but this sounds like an occasional backup only.

but this sounds like an occasional backup only.

Wonder what would happen if they should discover that the use of the "backup" reduced overall operating cost?

Never happen so no problem

Sometimes in making calculations assessing BTU's per gallon of different fuel will help somewhat although in the end different fuels don't necessarily give the same efficiency.

Propane (LPG) 84,300 btu per gallon

#2 diesel 129,500 btu per gallon

LGN 75,000 btu per gallon

CNG 900 btu per cu/ft

Other considerations are that diesel can contaminate your well although it is very unlikely with today's dual walled tanks and the quality of the engine fuel lines, filters etc. Diesel also has a storage life and again there are ways to extend it but it costs more money.

Propane won't contaminate the well and stores forever but to get the same run time you would need a larger storage tank (might not be any more expensive than a dual walled diesel tank) and maybe a larger sized engine to get the same horsepower output.

I probably wouldn't consider the natural gas because (1) it wouldn't be reliable in a disaster situation from a local distribution line and (2) storing LNG is exttremely expensive because of the high pressure tanks needed.

Hello.We also have a small town/community well system.In a recent meeting with the DEP,they encouraged home owners to move away from fuel oil heating systems to natural gas or propane.They are concerned with leaking fuel oil into our groundwater.In our area the backup generators are self contained outside,not in the well house. Cost is around $4,000.They use about 60 cu. ft./hr LP or 120 cu. ft/hr NG.Hope this helps.

Do you need for the generator to start automatically, or will it be started manually?Do you want a water cooled, or air cooled generator? Is noise a factor when generator is running?Do you have a qualified diesel mechanic on payroll to perform routine maintenance or will you have maintenance done under a service contract?

How often do you anticipate needing the backup?

If it has to run continuously for long periods, the diesel is more reliable, but more expensive.Most cities and municipalities used diesel for backup of pumping stations, if that is any comfort.

A containment wall around the engine will provide a sense of security if anything on the engine leaks, or if leaks occur during servicing.

Is natural gas available in your area? If so, have you considered a fuel cell instead? Very quiet,super efficient.Very little maintenance required.No petroleum leaks to worry about.

More info would be helpful, such as pump hp, service factor of pump, starting amps of pump motor, heating requirements during winter for heat tracing of piping, etc.

If natural gas is available in the area I expect they would not be using propane for heating.

If the propane tank can be buried it is the safest location.

Every time I study up on this I get conflicting opinions on the life of diesel - how long can it really sit before becoming a problem?

Have the engineer do a study of total operating cost for 5yr/10 year period.There are significant federal and state incentives for fuel cell installation, and credits for KW's generated by fuel cells.

I think he will be surprised at the total cost of ownership of the fuel cell systems.

If he wants to charge extra for this study, do it yourself with Google.There are many manf. of fuel cells that will provide the information freely.

Then you can present the facts to backup your alternatives.

Hydrogen is cheaper than propane in many areas, and fuel cells are also available that use methanol reformers to make their own hydrogen.This is a very compact way to store the reserve energy.

The fuel cells require very low maintenance, and are very quite, so zoning issues are not likely.

From Capt Moosie - Diesel can get stale over a 6 month period. However, most municipalities have a DPW that employ mechanics to work on their highway equipment which usually have diesel engines, so it is fairly easy to fix an genset diesel engine that has gone out of warranty or has an expired service contract. Most likely Joe Blow down at the corner garage cane fix the darn thing!

From Smoothy - Diesel fuel doesn't need to be kept "Fresh" like gasoline. 20 or 30 year old (and even far older) diesel fuel will work perfectly well as long as its not contaminated.

This is where the discussion normally ends up.

In the near future I need to buy a generator - diesel is preferable as it is cheaper here but I do not an alternate use for it.

Thanks!

HiTekRedNek has an great alternative in suggesting hydrogen fuel cells, particularly when Federal and State energy grants and credits are utilized + it's a very clean burning fuel type and economical as all heck once one gets by the Principal Costs and capitalization. The technology is now mature and has been proven over the years.

I forgot to mention this fuel source.....duhhhh is me! LOL

GA for his answer!

Since you are in Vermont we're talking cold winters. You might want to heat trace the fuel supply line to the diesel if you go with diesel. If you lose heat in that pump room the diesel fuel might not flow too well to the diesel engine. Diesel and #2 are very close and many a home owner in New Jersey has regretted not tracing their fuel oil lines after a long cold snap when their tank is outside the house even in an enclosed shed next to the house.

The point made about the DEP is very true here in NJ also. A leaky tank has cost many a homeowner well over $20,000 and if it hits the water table even more.

Really good summary!

Propane down in New Mexico (delivered) fluctuates wildly in price between summer and winter purchases. I can get $2.50 if I buy in bulk - even for delivery in January, where a January purchase will cost me over $5.00.

Used to live on LI also. PR is much nicer. I would go for propane. Far easier to start in the winter. We used propane to power the tower sites just for this reason. As others have pointed out you aren't providing enough info. What is your power failure history?

Onlly a few hours per year in power failures, but a large company has taken over our little municipal and I don't know about their rate. I suspect it will be low, but we'll be part of a larger network and who knows when they will get to us.

The capital plus operating costs together are what count. Here a propane fuel generator costs excessively in comparison to a diesel or gasoline fuel unit.

Gasoline is about 10% more costly per liter than diesel - so my only real choice is diesel.

Our town has a propane dealer who will sell us propane for $2/gallon. They have service people as well. The generator will be outside and I wonder what the starting problems in winter will be. It is possible to have temps as low as -25F. If diesel is cheaper on the capital end, why are diesel engines so much more than gas when you buy a car?

Different engine when you start talking about common rail diesel - more expensive.

Here prices are in the range of

95 ocatane - 8,61$ US per gallon

euro diesel - 7,74$ US per gallon

LPG - 5,06$ US per gallon

Russ, are those Turkish fuel prices?

Prices in the USA for each fuel are considerably much lesser...

Turkish prices - can't really import fuel

Turkey followed the Euro model as regards fuel as a great tax source.