How Much Propane Does a Generator Use?

We are modern humans. Our fast-paced lives revolve around the use of electricity. We are desperately dependent on the power supply for performing our day-to-day activities. We usually take all the blessings of electricity for granted until the damned hour comes and the power runs out. Suddenly all the electrical appliances become useless. 

Do You Really Need a Generator?

The generators are the saviour in blackout situations. It is an excellent question to ponder over which fuel is best for running generators. Many folks will tell you that propane-powered generators are costly and propane burns a lot quicker than natural gas, but It is never a good option to go for a natural gas-supplied generator. There are several prevalent reasons for power generators using propane. Natural gas-powered generators are not very reliable in emergencies such as snowfall or heavy rain, which often result in a power outage. The Natural Gas supply lines are often affected by severe weather, such as severe storms, even if the supply is available at home. So you cannot count on natural gas for running the generator during the power outage because most probably, the gas supply would also be halted during that time. The propane generators are very convenient for running a home generator for keeping your lights on and your TV running during a power outage. 

Being able to keep your house warm during an ice storm or heavy rain is a heavenly blessing. Propane-fueled generators are the most reliable of all the available generators in the market regarding home use. The propane-powered generators are economical that come with budget-friendly air-cooled engines. So, suppose you already have a generator at home, and unpredictably you ran out of your propane supply or are thinking of buying a propane-fueled generator and want to know how much propane a generator uses. In that case, you are at the right place. How much propane a generator use depends upon multiple factors. It is best to consider several aspects that will determine your need for the propane supply to never get into trouble out of the blue due to unforeseen withdrawal of the propane. You will never get into trouble due to the unnecessary thought-less use of propane for running the appliances, which you should not power if you have the restricted propane storage. LPG(propane) has a longer shelf life, and it burns clean. And most propane generators come with a user instruction manual that helps the user operate and manage the generator. Most propane generator manuals have additional information on how many gallons of propane the generator consumes per hour to create a specific amount of electricity.

Factors Determining the Propane Consumption by the Generator

It is always better to know how much minimum fuel you need for your generator will satisfy your needs. It does not depend upon the situation. Whether you can store a suitable amount for the emergency or if you think that fuel is hard to come by during a power cut or an emergency, and thus you want to have a clue of how much propane you should store. It depends upon how much you can compromise on your generator usage. How many appliances you can turn off to make your propane supply last longer. To avoid getting into trouble during the next unpredictable electricity blackout, let’s understand how much propane you should save for that situation.

Size and Company of Your Generator

Choosing the right sized generator for your home is a task that requires a lot of effort and thought. After selecting a sound generator, based upon the estimated power load of the house, one must use such extension cords which have a good current carrying capacity. This will avoid the voltage drops, which result in excessive propane burning for compensation of electricity loss due to electrical resistance during the current flow. It is estimated that for an average household during a short electricity blackout propane tank of 120 gallons will be enough for 24 hours when the average load on the generator is 50 per cent or less. A 400-to-500-gallon propane storage tank will be enough for a more extended period, for example, a maximum of 9 or 10 days.

Suppose the power load on the generator is 50 per cent on average and the propane supply is 120 gallons. A 22-kilowatt generator will work for  48 hours approximately where a 20-kilowatt generator will run for 50 hours on a 120-gallon propane tank. Thus, how much propane does a generator need depends upon the size of the generator; the bigger the generator, the quicker it will burn the propane, and thus it will run for a lesser time. 

Running Time

The running time of any electrical appliance has a very profound effect on its working and fuel storage. Most propane generators burn 2 to 3 gallons of propane per hour. Majority of the propane tanks that we keep at our homes, whether underground or above, are 500 to 1000 gallons. On average, If a 16kilo-watt generator runs at its total capacity, it burns 2.4 gallons of propane per hour. 

Appliances Load

Your need for propane depends upon how many appliances you want to run and how much load weight is present in the generator. The more the weight of the load on the generator, the lesser its operating time will be.  A small household that requires power for only a few lights, a refrigerator, and a TV or electrical heater, a small 10kW generator is sufficient. So, to err on the side of caution, you need an independent backup propane storage tank available if the power outage prolongs.

Calculating How Much Propane a Generator Use Per Hour

You can also not run a generator off the last 20% or so of a propane tank because that much propane will not deliver adequate pressure. Thus, it would be best to calculate how long the generator would run before reaching the last 20% of the fuel storage so that you may cut on your power usage by the time the propane amount becomes limited. 

Crunching the Numbers 

We need to have some basic assumptions about the efficiency of the generator for accurate calculations. The amount of electricity produced by an engine is called horsepower. Any engine needs one horsepower to generate 500 watts per hour. Now we have another unit, BTU (A British thermal unit is a unit of heat). If the generator is running under load, then one horsepower requires 10,000 BTU in an hour, and we know that one gallon of propane weighs 4.2 pounds and contains 92,000 BTU per gallon. A 2-horsepower generator generates1000 watts of electrical output. To generate one horsepower mechanical energy, 10,000 BTU per hour of fuel is required. In reality, the load on our generators is not always the same, and thus the power we draw from the generator is not always constant. The essential electrical appliances that we always use make up the baseload. The peak load on the generator occurs when all the electrical appliances are running on the generator. This puts extra pressure on the generator, and it burns more propane. The peak load can make up for an increase in the contingency. First, we should know how much watts or kilo-watts of energy all our electrical appliances need to calculate how much power our generator needs to produce(horsepower) To run our electrical devices.   

Horsepower = (watts / 500)

Horsepower = (5000 / 500)

Horsepower = 10HP

Here we assume that all our essential appliances put the 5000-watt baseload; you would need ten horsepower. As stated above, 1onehorsepower requires 10,000 BTU in an hour. Now let’s find out how many BTUs 10 HP will need per hour.

BTU = horsepower x 10,000.

BTU = 10 horsepower x 10,000 BTU

BTU = 100000 BTU

In this example, the 5000-watt load would use the fuel that produces 100,000 BTU per hour.

Now, let’s calculate how much gallons of propane 100,000 BTU equates to.

Gallons of propane = BTU / 92000

Gallons of propane = 100,000 / 92000

This concludes that a generator with a 5000-watt load per hour would consume 1.086 gallons of propane.

1 gallon of propane = 4.2 pounds

In ratio:

Gallons of propane: pounds of propane

1.00:     4.2

1.086:     4.2 x 1.086 = 4.56 pounds

So, 1.086 gallons of propane weighs 4.56 pounds of propane

One gallon of propane weighs 4.2 pounds so, 1.08 gallons of propane would weigh 4.56 pounds. An average size generator can run a 5000-watt load for 11.6 hours approximately.

Total Propane Required

To have a realistic notion of our total propane requirements, including the peak hour load, we need to add a contingency to the previous value. The peak load adds an extra power burden to draw when appliances start-up, plus any small additional appliance load we may want to use.

Now, to add in the contingency or unexpected load need, we use the following formulae;

Total propane required = baseload + peak load + contingency

Total propane = 1.086+ 5.76 + 0.64+ 2.0 = 3.726 gallons

All the above calculations are approximate and can vary due to the differences in the efficiency of generators. But You can have a basic idea of your propane need keeping in view the above calculations.