I am looking for the stand by large generator 15-20kw (to use all the power on one transfer switch). The problem is that stand by generator require large propane tanks (expensive to install). I would like to find a stand by generator that i could run off gasoline and use all of it available power. I think this would the most economical solution. In case of propane/natural gas the cost of propane tank installation is significant. The diesel stand by generators are significantly more expensive. So far I have found tri-fuel13kw portable generator that has several outlets. In this case not all the power can be utilized.
Why do you need something that big? A 15kw gasoline generator is going to use 2-3 gallons per hour fully loaded and close to 1 gallon per hour at light load, and a 20 even more than that, hence you might not have to have a large propane tank but you will have a large gasoline tank. That is enough capacity to run a clothes dryer, water heater, and range (all electric of course) all at the same time. I personally got one of the Chinese 2 stroke 800w generators, its KWH per gallon performance is poor but in the winter it will run my gas furnace just fine and it only needs to be run several hours per day to keep the place above freezing. I have some batteries and inverters for lighting and I can cook with a portable propane camping stove. Since gasoline doesn't store well without going bad you will have to rotate your stock of it probably by using multiple small cans or by having a big tank and using your supply in your car and getting more as needed. Propane in a leak-free tank will store indefinitely Diesel will also store long term by occasionally treating it with fungicide and keeping any water drained off the bottom. Natural gas is obviously just piped in.
Well i think all stand by generator require large propane tanks, its always for optimum performance
I don't get what you mean by not able to use all the power. The generator will produce it's rated output, and little more, from one or any combination of it's outlets - single or three phase, including the 12 volt charging system. The total output of the machine is available as a function of the total load connected, not the number of plugs or the variety of outlets - it is the total load that counts. Petrol is the least efficient, and the most dangerous fuel to use and store. The amount of fires involving LPG or similar fuels is a fraction of those involving petrol in road accidents for a start. A slow speed Diesel generator correctly sized for your normal load (allow 33% additional capacity for starting induction motors etc.) will use the least fuel, and be the longest lasting by a large margin of any of the choices you suggest above. The cheapest initial option will be a petrol powered system, but the most expensive to run, and the earliest to wear out. The running costs will be much cheaper on propane etc., and the engine will run much cleaner and last longer as a result. A high speed diesel unit will cost more than the petrol version, but will not be as expensive as the better slow speed types, it will be economical, but is not going to last as well as the slow speed models. Well made slow speed diesel units will cost the most to install, but will be the most economical both to run, service and in longevity. The cheapest initial option I have found, is always the most expensive in the medium and long range. If the unit is purely for emergency power, it should be run under load every month at least, and the fuel must be kept fresh, or treated and constantly monitored to withstand long term storage - this is where the propane storage is particularly effective. The worst thing that can be done with any backup power system is to allow it to sit for any length of time without being used. Many fail at critical times because of this.
