Energy is never used up, only transformed. Images by jcomp@freepik

How energy works

Saving energy is always a good thing, right?  Whether it’s saving our own energy, fossil fuels, or even renewable energy, using less energy saves time and money.  Knowing how energy works can help us save it because sometimes it works in surprising ways.

Endless energy

Physics tells us that energy is never used up, only transformed from one form to another.  For example:  Nuclear energy from the sun is transformed into light energy, which travels to Earth.  Light is absorbed by the leaves of plants which convert it to chemical energy, stored in the form of carbon. Plants that rot down and compress over millions of years make oil, which is concentrated chemical energy.  A motorcar converts oil into kinetic energy (motion) plus heat and noise.  The motion causes friction against the air becoming heat energy, warming the air and the road.  At no point is any of the energy ‘used up’.  That is a fact of the universe.

Where does the fuel go?

As well as transforming energy, the car transforms the fuel itself, from a liquid to a gas. Imagine that over a few months I put 1,000 litres of a carbon-based fuel like petrol (weighing around 1 tonne) into my car.  To burn it the engine takes in oxygen and turns all of the fuel into carbon plus oxygen (carbon dioxide).  For every tonne of carbon, 2.7 tonnes of oxygen are used, and the output through the exhaust is 3.7 tonnes of CO2.  The burned matter is never “used up”, which is why it produces such a vast quantity of greenhouse gas.

Energy highs and lows

Of all our activities, the ones that use the most energy are heating things up and moving them around. That’s why insulating homes and flying less are two of the biggest actions we can take to reduce our carbon footprint. Things that only use a small amount of energy are light, sound and communications. LED light bulbs produce light without heat, so use much less energy than traditional light bulbs.

Terrible waste is good news

In a funny way, it is really good news that our society is so inefficient and wasteful.  If we were already very efficient it would be much harder to get to net zero.  But our systems are currently incredibly wasteful, which means it is relatively easy to make them more efficient.  For example, insulating your home can reduce heating by 80%, LED light bulbs are 80% more efficient than incandescent bulbs and electric cars use around 70% less energy than petrol cars.  Many of us also take more journeys and transport goods further than we really need to.  All this is great news because it means we can conceivably reduce our energy use by 80%, and use renewable energy like wind and solar to meet our remaining needs.  This is how we’ll get to net zero by 2050.

To do list for humans

Activities that create the most CO2 are; driving cars, heating homes, flying planes, manufacturing and transporting products, and intensive farming. So in a low-carbon lifestyle you live closer to work, insulate your home, take the train on holiday, buy long-lasting products and eat local, seasonal organic food.  What makes it such a positive step is that most of these things also improve your quality of life

So here’s to lifestyles that use energy efficiently and deliver greater enjoyment.

Written by Mukti Mitchell