Generator fuel
- Thread starter hawkeye23
- Start date
- Status
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
No. Not without adding an ignition system and an alternate fuel delivery system (that is, for practical purposes, replacing the engine itself.) NG operation will not allow for diesel ignition of the fuel charge, nor can the NG be delivered through the injectors of the diesel engine.
A gasoline fueled generator which does not use fuel injection can be converted to NG or LPG, or set up for switchable fuel input.
The power rating of the gasoline engine will be reduced when operated on either NG or LPG, since you cannot produce as dense a fuel charge in the cylinder.
At 1500 KW, there probably aren't any natural gas options. Diesel is probably the only way to go.
At about 100 to 150 KW, NG generators get so expensive that anything larger would almost have to be diesel.
And your generator is 10 times larger.
eHunter
Senior Member
- Location
- North Texas & Georgia
Not a completely accurate statement.
CAT, Cummins/Onan and numerous other genset manufacturers offer NG/LPG fueled gensets up to 2500KW and some beyond 3000KW.
http://cumminspower.com/en/technical/documents
http://www.cumminspower.com/www/com...caldocument/SpecSheets/LeanBurn/na/s-1623.pdf
http://www.cumminspower.com/www/com...caldocument/SpecSheets/LeanBurn/na/s-1463.pdf
Last edited:
eHunter
Senior Member
- Location
- North Texas & Georgia
The short answer is it may be possible, but will most likely be a cost prohibitive and problematic conversion product.
I have personally known several units that have been converted and none of them have been a cost effective success story and most have been continually problematic with a lot of required maintenance and unscheduled downtime.
Last edited:
- Location
- New Jersey
- Occupation
- Journeyman Electrician
If you're using the generator for Article 700 emergency systems it needs to have an on site fuel supply capable of providing 2 hours of operation at full demand.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
+1
Both of those illustrate that for high power engines fueled by NG, it is necessary to use turbocharging to get good operation. For LPG, either liquid feed or fairly high pressure gas feed is needed. For that reason, a simple conversion of a gasoline engine which was not originally multi-fuel can be difficult in these power ranges.
And looking at the requirement infinity pointed out, storing and using LPG can be a problem in cold environments. Storing Compressed natural gas in those quantities takes large heavy pressure tanks (thousands of psi.), while liquified natural gas has to either be cryogenically refrigerated or used at a high enough constant rate to cool the tank by boiling off gas.
Last edited:
Yes, you are right - they do make natural gas generators that large.
But if you look at the engine displacement for a 1000 KW natural gas vs. a 1000 KW diesel, you will see the NG generator has a displacement twice as large - 60 liters vs. 30 liters.
You can imagine what that does to the price of the generator.
I think it would also squash any attempt at a conversion, unless the generator is currently twice as large as it needs to be.
sparkyrick
Senior Member
- Location
- Appleton, Wi
Diesel engines don't have spark plugs. So I say no, you can't convert from diesel to NG/LP.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
And, that double displacement is also turbocharged!
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Really large generators that use natural gas as the energy source are typically using the gas to heat a boiler and the steam powers the generator:happyyes:
sparkyrick
Senior Member
- Location
- Appleton, Wi
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I believe they call that a "Power Plant"
Yes but is still a natural gas powered generator:happyyes:
sparkyrick
Senior Member
- Location
- Appleton, Wi
eHunter
Senior Member
- Location
- North Texas & Georgia
Or the current trend of natural gas fired combined cycle turbines.
There have been a large number of coal fired power gen plants replaced by combined cycle NG turbines the last few years.
Last edited:
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Even if you could find a way of providing a spark, in the cylinders, many other problems comes to mind from knowing how a diesel operates, the main one is a diesel has a 20:1 up to 30:1 compression ratio, firing a diesel off gasoline or Propane/NG would blow the heads right off it, seen it happen when someone used to much ether, also a diesel does not have a throttle, the air intake is wide open so a method of controlling the air intake would have to be found, at a 22:1 compression ratio, a diesel would suck most throttle plates right into the engine, ever tried to stop a runaway diesel with a piece of metal, it will suck the metal right into the intake if it doesn't collapse/implode the intake, another problem is lubrication of the upper combustion area of the engine, a diesel depends upon the fuel to lubricate the valves and piston rings as well as other parts of the engine, so this would also be a big problem.
So to even start thinking of converting a diesel to run on NG or Propane, one must figure a way to lower the compression ratio, provide a intake air throttle, and find a way to provide a spark inside of the combustion chamber, so then why not just replace the diesel with a gasoline engine with a NG throttle body, then sell the diesel back to the manufacture or someone who could use it which would cut some of the cost of the new engine.
Many gas turbines can burn many different types of fuels I have heard of many of the larger generators being equipped with gas turbines (basicly a jet engine with an output shaft) just for this reason, but these were for co-gen plants.
Last edited:
eHunter
Senior Member
- Location
- North Texas & Georgia
I understand your concerns, however there are conversion kits that work... just not without some problems.
These kits are sold by some OEM engine builders and third party/aftermarket companies. Some work better than others.
The conversions that I have been involved with included a completely new induction system including replacement turbos, cylinder heads with larger combustion chambers(to lower the CR), spark plugs, valves that will survive NG/LPG use, a new ECU engine management system, ignition system, coils, crank position trigger and an assortment of tubes, sensors, fasteners, wiring harnesses, throttle body, TPS, detonation sensors, etc... and reprogramming for the genset controller.
Most of the diesel engine conversions I am familiar with are due to state emissions reg compliance.
The converted units we worked with did not like taking block load transfers without a wide rpm, voltage, frequency swings, they really grunted with anything more than about 55-60% of total capacity. They also did not work well in paraleling instalations.
If I were to recommend a NG/LPG recip genset, it would be a factory, purpose built unit by one of the larger genset manufacturers.
Most power gen turbines in North America are NG fueled, for economic and emissions reasons. But most shaft turbine engines can be adapted to run on just about any fuel.
Last edited:
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Using too much ether with a gasoline engine can blow heads off also, and likely easier than in a diesel engine. I don't see that the compression ratio has much to do with how much air will be sucked in. A cylinder has a specific volume and the fact there is no throttle plate on a diesel engine is why it can suck more air in without additional assistance from a turbo charger. It may have tighter fitting piston rings and can create more vacuum if there is a restriction in the intake, don't know that it is that much more that the typical throttle plate on similar sized gas engine couldn't handle it though. Diesel has more energy by volume in it than gasoline. The diesel engine has heavier heads, block, pistons, etc. because they are expecting more power out of each stroke than a gasoline burning engine. One may even question if you can put enough gas/air mixture into a diesel designed engine to run very effectively, overcome the higher compression and still have any usable output power left over. It can probably be done, but is not going to be all that efficient of a machine either.
Just a few thoughts, feel free to come down on them as I don't really have that much to back them up with.
eHunter
Senior Member
- Location
- North Texas & Georgia
In hurk27's favor, I have seen a diesel genset engine that was on an oil rig that experienced "run away" when there was a significant release of hydrocarbons during an uncontrolled well control event(minor blow out).
The diesel genset engine normally operated at 900 rpm producing 3.3 MW but when its intake was enveloped in a cloud of methane(NG) it sped up uncontrollably to close to 3000 rpm before the safety controls kicked in dousing the intake with CO2 and slamming kill plates across the air intakes.
These measures stopped the engine run away without a violent engine explosion, but that engine did not run again.
It was taken back to shore and a new unit was sent to take its place.
The diesel genset engine normally operated at 900 rpm producing 3.3 MW but when its intake was enveloped in a cloud of methane(NG) it sped up uncontrollably to close to 3000 rpm before the safety controls kicked in dousing the intake with CO2 and slamming kill plates across the air intakes.
These measures stopped the engine run away without a violent engine explosion, but that engine did not run again.
It was taken back to shore and a new unit was sent to take its place.
robbietan
Senior Member
- Location
- Antipolo City
no, gas turbines dont need a boiler to operate. unless it is a combined cycle plant, where waste heat from the gas turbine is used to heat a boiler to produce steam.
and yes, our gas turbines used to be diesel powered until they were converted to NG
- Status