← Master refDOC-006 / FUEL-COST

Running Costs: Natural Gas vs Propane vs Diesel

Per-hour and per-day fuel costs at 50% and 100% load for every common kW rating. Real numbers with a calculator, not vague ranges.

TABLE-A / COST-RATE

Running Cost Comparison

Costs at 50% load (typical during an outage) and 100% load. Most generators run at 30 to 60 percent load during a real outage.

Size	Fuel	$/hr (50%)	$/hr (100%)	$/day (50%)	$/day (100%)
10 kW	Natural gas	$0.94	$1.89	$11.31	$22.62
10 kW	Propane	$2.00	$4.00	$24.03	$48.06
16 kW	Natural gas	$1.45	$2.90	$17.40	$34.80
16 kW	Propane	$3.07	$6.14	$36.85	$73.69
22 kW	Natural gas	$2.03	$4.06	$24.36	$48.72
22 kW	Propane	$4.27	$8.54	$51.26	$102.53
48 kW	Natural gas	$3.99	$7.97	$47.85	$95.70
48 kW	Propane	$8.54	$17.09	$102.53	$205.06

Based on recent EIA residential fuel prices: natural gas about $1.45/therm (latest EIA monthly, ~$15/thousand cubic feet), propane about $2.67/gallon (last EIA heating-season survey). Actual costs vary by region and supplier.

FORM-C / FUEL-RUN

Running Cost Estimator

Per-hour fuel cost at 50% load (typical outage load). Multiply by run hours for daily and weekly cost.

INPUTS

01 / Generator size

02 / Fuel

03 / Run hours per day

DAILY FUEL COST

$24.36

$2.03 / hour at 50% load

Extended outage (7 days)$170.52

TABLE-B / CONSUMP

Fuel Consumption Rates

Size	NG @ 50%	NG @ 100%	LP @ 50%	LP @ 100%
10 kW	65 cu ft/hr	130 cu ft/hr	0.75 gal/hr	1.5 gal/hr
16 kW	100 cu ft/hr	200 cu ft/hr	1.15 gal/hr	2.3 gal/hr
22 kW	140 cu ft/hr	280 cu ft/hr	1.6 gal/hr	3.2 gal/hr
48 kW	275 cu ft/hr	550 cu ft/hr	3.2 gal/hr	6.4 gal/hr

SECT-C / 10YR-FUEL

10-Year Fuel Cost: NG vs Propane

Natural Gas

Utility-fed. Never runs out. Cheapest per hour.

Install premium$0 (if line exists)

New gas line tap$300 - $1,500

Per outage day (22kW, 50%)$24.36

10-yr fuel (72 hr outage/yr)$1,460

Propane

Off-grid. Tank required. Higher per-hour cost.

Tank install$800 - $2,000

Tank refill (250 gal)$550 - $700

Per outage day (22kW, 50%)$51.26

10-yr fuel (72 hr outage/yr)$3,075

FINDING

10-year fuel savings with natural gas: roughly $1,615. However, if you do not have NG service, running a new line ($3,000 to $5,000) may offset the savings. Check current propane pricing at propanecostpergallon.com.

TABLE-C / LP-TANK

Propane Tank Sizing

Tank Size	Install	Refill	22kW @ 50%	22kW @ 100%
250 gallon	$800 - $1,200	$550 - $700	130 hrs (5.4 days)	65 hrs (2.7 days)
500 gallon	$1,200 - $2,000	$1,100 - $1,400	260 hrs (10.8 days)	130 hrs (5.4 days)

Usable capacity is approximately 80% of tank size. Top off tanks before storm season; prices spike during outages.

DOC-001/

Total cost overview →

DOC-005/types

Type & fuel decision →

DOC-010/save

Fuel saving strategies →