The recent explosion at Hemel Hempstead got me thinking about energy dynamics, of all things. This isn’t anything unusual, I often think about energy dynamics whenever I’m near a petrol station, or gas cannister, or charcoal, or any other fossil fuel-derivative, and I’m always slightly awed by the whole thing.

The energy in a fossil fuel, like oil or petrol, originally reached the Earth in the form of sunlight millions of years ago, when plants captured it and used it to make basic carbohydrates like sugar. These sugars were then further processed into things like wood. Eventually the plants died, and what was left became oil over millions of years.

It’s the efficiency of the whole thing that awes me. I think plants are only able to capture about 2% of the sunlight they receive. That means the remaining 98% of the sun’s rays went into things like heating up lizards and creating forest fires. When the plants died they rotted: the organisms involved in decomposing the dead plants would have taken some of the energy out of the plant, and whatever was left would have turned into oil. But only under certain circumstances and in certain places.

Even so, the energy in the oil created an explosion that was heard 50 kilometres (30 miles) away, and a fire that took four days to put out.