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An appreciation of ENERGY
Energy, as my old physics textbook says is the ‘capacity to do work’. It is a mysterious commodity – it cannot be created or destroyed but can be changed from one form into another. However, energy is progressively degraded as we use it. The energy released from burning a piece of coal may help to cook a burger on a BBQ but can’t be regathered – that’s to do with entropy
 So where did the energy of the so called ‘Big Bang’ come from? A good question, indeed. However, a more urgent question is obtaining the energy to boil the water for the next cup of tea… Do we have any appreciation of how much energy it takes to boil water?
How much water? Well let’s say 500ml – enough for two mugs of tea. To heat it by 1oC – one degree centigrade takes 4.2 x 500 Joules. So the cold water from a tap probably needs to be heated by 90 degrees, that’s 4.2 x 500 x 90 or 189,000 Joules
 To appreciate this: if you were able to lift 100kg in a clean and press over your head at the gym (very hard!) that would be using 100 x 10 x 2m Joules or 2000J – (Force = m x a and Work = Force x distance moved)
If you did this lift in one second that would be a power of 2KJ the energy used by your average 2kW electric kettle in ONE second!
So how many seconds does it take to boil 500ml? 189,000 / 2000 = approx 90 seconds. So lifting 100kg from the floor to above your head 90 times is the energy it takes to make two mugs of boiled water!
I find that staggering! It shows the value of energy. We must not waste it
 Let’s briefly consider an offshore wind turbine. Think of the energy needed to make the components – staggering. Then transport them by road and ship to their place at sea. Then the energy to make the foundations and install it, and the energy to make and lay the cables to take the energy to shore! The energy to service and maintain the turbine and the quantity of oil needed to lubricate the turbine – all staggering amounts! How many years does it take for net gain of energy from a turbine?
According to an article in ‘Windpower Engineering and development 2009’ by Taylor Johnson it would take 22 years to return the investment on a single wind turbine. [The lifetime of a turbine is projected as 20 years]. Makes you think – use energy wisely!!
The average adult needs about 8700KJ (about 2070 kcal) daily to maintain body weight. That’s boiling the above kettle 46 times. So yes, Energy makes our world go round!
Shall we start on the Sun… it loses around 4 million tons of its mass through thermonuclear processes, per second – converted to energy according to E=mc2 . Who said physics was boring?
Hebrews 1:3 tells us He upholds all things by the word of His power. When you have some appreciation of the forces and energy at the subatomic i.e. quantum level you can see it takes some upholding. Our job is to live and manage our wonderful planet and its amazing resources in a sustainable way. That includes our behaviour and treatment of each other… we will be held accountable
Peter Gray-Read, science teacher / evangelist
images courtesy of Peter Gray-Read
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