At a Glance
Natural Gas
Unlimited Supply
Pros:
- ✓Unlimited fuel supply during outages
- ✓No fuel storage or refilling required
- ✓Lower fuel cost per hour of operation
- ✓Cleaner burning (fewer emissions)
Cons:
- −Not available in all areas
- −Gas line can be damaged in disasters
- −Requires professional gas line installation
Best for: Homes with existing natural gas service
Propane (LP)
Available Anywhere
Pros:
- ✓Works anywhere, no utility connection needed
- ✓Higher energy density than natural gas
- ✓Fuel stored on-site (disaster-proof)
- ✓Long shelf life (indefinite)
Cons:
- −Higher fuel cost per hour
- −Requires tank purchase or rental ($500-$3,000)
- −Limited runtime (need to refill tank)
Best for: Rural areas or homes without natural gas
Already Know Your Fuel Type?
Our calculator sizes your generator regardless of fuel choice.
Size My GeneratorCost Comparison
| Item | Natural Gas | Propane | Notes |
|---|---|---|---|
| Installation Cost | $3,000 - $6,000 | $3,500 - $7,000 | Propane requires tank installation |
| Fuel Cost (per hour) | $1.50 - $3.00 | $2.50 - $5.00 | Based on 22kW generator at 50% load |
| 24-Hour Outage Cost | $36 - $72 | $60 - $120 | Varies by load and local fuel prices |
| Tank Cost | $0 | $500 - $3,000 | Tank can be purchased or rented |
| Annual Maintenance | $200 - $400 | $200 - $400 | Similar maintenance requirements |
Propane Tank Runtime Estimates
If you choose propane, tank size determines how long you can run during an extended outage. These estimates assume 50% load, which is typical for most outages.
| Tank Size | 20kW Generator | 10kW Generator |
|---|---|---|
| 250 gallons | 72-96 hours | 144-192 hours |
| 500 gallons | 144-192 hours | 288-384 hours |
| 1000 gallons | 288-384 hours | 576-768 hours |
* Most residential propane tanks are 250-500 gallons. A 500-gallon tank provides 6-8 days of runtime for a typical home.
How to Decide
Do you have natural gas service?
If yes, natural gas is almost always the better choice. It's cheaper to operate, requires no storage, and you'll never run out during an outage (unless the gas main is damaged). Check with your utility to confirm service availability.
Are you in a rural area?
If you're outside municipal gas service areas, propane is your best option. The higher fuel cost is offset by the reliability of having fuel stored on your property. Consider a 500+ gallon tank for extended outages.
Worried about disaster scenarios?
Propane has one advantage: your fuel supply can't be cut off by a damaged gas main. In earthquake zones or areas with aging infrastructure, this backup independence can be valuable. Some homeowners in hurricane zones prefer propane for this reason.
Frequently Asked Questions
Can a generator run on both natural gas and propane?▼
Yes! Most Generac and Kohler generators are "dual-fuel" and can run on either natural gas or propane. The generator comes configured for one fuel type, but a technician can convert it for about $200-$500 if your situation changes. This flexibility is one reason standby generators are preferred over portable units.
Which fuel is more reliable during disasters?▼
It depends on the disaster. Natural gas is more reliable for most outages since you have unlimited supply. However, in earthquakes or major disasters, gas mains can be damaged. Propane stored on-site can't be "cut off" but you're limited to what's in your tank. For maximum resilience, some homeowners install dual-fuel generators with both connections.
How much does it cost to run a generator for 24 hours?▼
For a typical 22kW generator at 50% load: Natural gas costs about $36-72 per day, while propane costs about $60-120 per day. These costs vary based on local fuel prices and how much of your home's load you're running. During a real outage, costs are often lower since you're not running AC and appliances constantly.
How big of a propane tank do I need?▼
For most homes, a 500-gallon tank is ideal. It provides 6-8 days of continuous runtime for a 20kW generator and costs $1,500-$2,500 installed. A 250-gallon tank is the minimum recommended (3-4 days runtime) and costs $800-$1,500. In areas with frequent long outages, consider a 1,000-gallon tank for 12+ days of runtime.
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