100 CF of natural gas to 100 watts/hr of electricity. What produces more kilo calories?

Question

Support answer. Trying to price local natural gas, which is very high, to electric use, which is cost effective. Thank you in advance.

Answer 1

First of all, watt/hr is meaningless. I hope you mean watt-hr, a unit of energy.

From my calculator:

100 watt-hr = 0.1 kw-hr = 360 kJ = 341 BTU = 86 kcal.

You may mean 100kw-hr, a much more reasonable unit

100kw-hr = 360 MJ = 341000 BTU = 86000 kcal

one standard cubic foot of natural gas produces around 1,030 British Thermal Units (BTUs)

100 ft³ therefore = 103000 BTU = 30 kW-hr = 109 MJ = 26000 kcal

Answer 2

See this PDF file, page 10 and 11:

http://geoheat.oit.edu/ghp/survival.pdf

It says energy per unit is:

Propane - 90,000 Btu/gal

Natural gas - 100,000 Btu/therm (1,000 Btu/ft3)

Electricity - 3,413 Btu/kWh

Simplifying all the math, adding in efficiency and local cost per unit  they list equations to come up with the cost of a mega-BTU.

Propane is stupid expensive here (> $3/gal) and electricity really cheap ($0.078).   I swapped out my propane water heater for electric two years ago with nice results.

for $3.06/gal propane and 87% efficiency, = $39.04/M-BTU

for $0.078/KWhr electricity, = $22.85/M-BTU