As we estimate our consumption of energy for heating, transportation,
manufacturing, and so forth, the aim is not only to compute a number for
the left-hand stack of our balance sheet, but also to understand what each
number depends on, and how susceptible to modification it is.

In the right-hand, green stack, we’ll add up the sustainable produc-
tion estimates for the United Kingdom. This will allow us to answer the
question “can the UK conceivably live on its own renewables?”

Whether the sustainable energy sources that we put in the right-hand
stack are economically feasible is an important question, but let’s leave that
question to one side, and just add up the two stacks first. Sometimes peo-
ple focus too much on economic feasibility and they miss the big picture.
For example, people discuss “is wind cheaper than nuclear?” and forget
to ask “how much wind is available?” or “how much uranium is left?”

The outcome when we add everything up might look like this:

If we find consumption is much less than conceivable sustainable pro-
duction, then we can say “good, maybe we can live sustainably; let’s look
into the economic, social, and environmental costs of the sustainable al-
ternatives, and figure out which of them deserve the most research and
development; if we do a good job, there might not be an energy crisis.”

On the other hand, the outcome of our sums might look like this:

– a much bleaker picture. This picture says “it doesn’t matter what the