We need to introduce simple arithmetic into our discussions of energy.

We need to understand how much energy our chosen lifestyles consume, we need to decide where we want that energy to come from, and we need to get on with building energy systems of sufficient size to match our desired consumption.

Our failure to talk straight about the numbers is allowing people to persist in wishful thinking, inspired by inane sayings such as “every little bit helps.”

Assuming we are serious about getting off fossil fuels, the scale of building required should not be underestimated. Small actions alone will not deliver a solution.

Let’s express energy consumption and energy production using simple personal units, namely kilowatt-hours. One kilowatt-hour (kWh) is the energy used by leaving a 40-watt bulb on for 24 hours. The chemical energy in the food we eat to stay alive amounts to about 3 kWh per day. Taking one hot bath uses about 5 kWh of heat. Driving an average European car 100 kilometers (roughly 62 miles) uses 80 kWh of fuel. With a few of these numbers in mind, we can start to evaluate some of the recommendations that people make about energy.