What do gigajoules, kilowatts and BTUs have in common, and why should you care? What they have in common is that they are different measurements of the same thing, energy.
A watt is a unit of electricity, one amp moving in a one ohm conductor, pushed by a force of one volt.
A joule is one watt per second or a force of one kilogram meter per second.
A kilowatt hour is 1,000 watts per hour and 360 seconds X 1000 watts, 3,600,000 Joules.
The BTU (British Thermal Unit) is the amount of heat needed to raise the temperature of one cubic foot of water one degree Fahrenheit, which is also equal to 1055.06 joules
Even though by definition all seem to be measuring different things, they are actually measuring the same thing, energy.
You should care because your home heating bill is a measure of energy that you have to pay for. If you live in Edmonton your home is almost certainly heated by natural gas, you may also be using gas for heating water, cooking or drying laundry.
Natural gas sold in Edmonton is billed as gigajoules. Home gas meters read in cubic feet. Gas furnaces are rated by BTUs per hour, electric heaters use electricity measured in watts, but may also be sold by their BTU output.
One kilowatt hour is 3414 BTU.
A cubic foot of natural gas produces 1000 BTU of heat energy.
A gigajoule is 947,817 BTU.
277.8 kilowatt hours are also one gigajoule.
Electric heat from the grid in Edmonton will cost consumers roughly ten times more than using gas. The reason it costs more in Edmonton is that 91% of Alberta’s electricity is generated from fossil fuels, coal (43%) and natural gas (49%) (Canada Energy Regulator). If electricity is generated using fossil fuel it will always cost more than using fossil fuel directly for the same reason a pound of french fries will always cost more than a pound of raw potatoes.
Using a month’s bills from Epcor for electricity and Direct Energy for natural gas for February 2020 at the regulated rate for domestic consumption, the delivered cost of a gigajoule of natural gas was $7.34 vs $61.90 for a gigajoule (277.8 kilowatt hours) of electricity, including all the administrative, fixed and variable delivery costs charged by these utilities. The regulated rate varies, fixed rates are available month to month, but do not expect the overall ratio of electricity costing roughly ten times more than gas to change as long as Alberta uses gas to generate electricity.
The future of fossil fuel energy looks dim, as it should. Climate change and greenhouse gas emissions notwithstanding, fossil fuel is a non renewable resource. Since the 1970’s people who know have been predicting that fossil fuels will eventually be used up. So far they have been wrong about when, but few could deny that eventually they will be right. As to what will replace it, a betting person might put their money on solar energy, which is already providing nearly all of the energy we use right now, including fossil fuels, solar energy that was stored for millions of years.
As for being greenest today, the more people in Edmonton can use natural gas for heating homes or water, cooking or drying laundry instead of electricity from the grid, the less impact their energy use has on the environment, given that 91% of Alberta’s electricity comes from fossil fuels 43% of which is coal. And using natural gas directly costs a lot less money than using electricity. Every time energy is used a little bit of it gets away, not all of it is used for its intended purpose.
Most of the electricity that arrives in your home was produced in a power plant that burned either gas or coal to make heat. Most, but not all of that heat was used to turn water into steam. Most (60%) of that steam energy got away. 40% efficiency is the limit for steam power. Most, but not all of that generator motion was used to push electrons back and forth in our grid. Some of the electrical energy was lost as heat when it was transmitted. When electricity is used for things other than heat, there are also losses, turning on an incandescent light bulb can literally create more heat than light (energy).
If there is any good news, it is that much of the electricity we use for all the things we use electricity for, like lighting, computers, TVs, refrigerators and vacuum cleaners ends up as heat inside our homes, which is good news for Edmonton, as our furnaces do not have to work as hard, but not so good news for Miami where it makes their electrically powered air conditioners work even harder.