about 24 times bigger. The “home” covers the average domestic electricity
consumption of a household, only. Not the household’s home heating.
Nor their workplace. Nor their transport. Nor all the energy-consuming
things that society does for them.

Incidentally, when they talk of the CO2 emissions of a “home,” the
official exchange rate appears to be 4 tons CO2 per home per year.

Power stations

Energy saving ideas are sometimes described in terms of power stations.
For example according to a BBC report on putting new everlasting LED
lightbulbs in traffic lights, “The power savings would be huge – keeping
the UK’s traffic lights running requires the equivalent of two medium-
sized power stations.” news.bbc.co.uk/1/low/sci/tech/specials/

What is a medium-sized power station? 10 MW? 50 MW? 100 MW?
500 MW? I don’t have a clue. A google search indicates that some people
think it’s 30 MW, some 250 MW, some 500 MW (the most common choice),
and some 800 MW. What a useless unit!

Surely it would be clearer for the article about traffic lights to express
what it’s saying as a percentage? “Keeping the UK’s traffic lights running
requires 11 MW of electricity, which is 0.03% of the UK’s electricity.” This
would reveal how “huge” the power savings are.

Figure I.2 shows the powers of the UK’s 19 coal power stations.

Cars taken off the road

Some advertisements describe reductions in CO2 pollution in terms of the
“equivalent number of cars taken off the road.” For example, Richard
Branson says that if Virgin Trains’ Voyager fleet switched to 20% biodiesel
– incidentally, don’t you feel it’s outrageous to call a train a “green biodiesel-
powered train” when it runs on 80% fossil fuels and just 20% biodiesel?
– sorry, I got distracted. Richard Branson says that if Virgin Trains’ Voyager
fleet switched to 20% biodiesel – I emphasize the “if” because people like
Beardie are always getting media publicity for announcing that they are
thinking of doing good things, but some of these fanfared initiatives are
later quietly cancelled, such as the idea of towing aircraft around airports
to make them greener – sorry, I got distracted again. Richard Branson says
that if Virgin Trains’ Voyager fleet switched to 20% biodiesel, then there
would be a reduction of 34 500 tons of CO2 per year, which is equivalent to
“23 000 cars taken off the road.” This statement reveals the exchange rate:

“one car taken off the road” ↔ - 1.5 tons per year of CO2.


The calorie is annoying because the diet community call a kilocalorie a
Calorie. 1 such food Calorie = 1000 calories.

2500 kcal = 3 kWh = 10 000 kJ = 10 MJ.

Figure I.2. Powers of Britain’s coal power stations. I’ve highlighted in blue 8 GW of generating capacity that will close by 2015. 2500 MW, shared across Britain, is the same as 1 kWh per day per person.