Clean Energy

Solar Energy – make like trees…

August 11 2020 | Dave Fardoe

Quick Quiz.

How much of the energy we use on Earth comes from the Sun?

100% – well ok, not quite as we do have some nuclear stuff.

However almost 100% – in fact, if we harnessed all the energy that does come from the Sun we wouldn’t need any other source of Energy for around the next 4.5 billion years.

Each hour 430 quintillion Joules of energy from the sun hits the Earth. That’s 430 with 18 zeroes after it!

In comparison, the total amount of energy that all humans use in a year is 410 quintillion Joules.

source – (2015)

The problem is that we are just not capturing it and even if we did we need to find ways of storing it and transporting it.

Nature has already solved the problem with trees, trees turn sunlight into energy via photosynthesis and that a 100% efficient process, that’s why trees don’t get hot in the same way we do as we process food. Excess energy is stored in the wood of the trees and released when we burn wood. Wood is easy to move around however it’s a great way of storing excess energy, excess carbon and they look good, so we should leave the trees alone. They also produce oxygen which we need, so that’s another good reason to plant trees not burn them.

Coal is another way nature solved the problem of solar energy, taking the same trees and biomass and, over years making coal – again easy to move but really bad and inefficient when we burn it. let’s leave he coal in the ground too. Oil is another process but you’re getting the idea.

So the problem is two fold – capture the solar energy, transfom (and move) the solar energy.

Firstly capture – Solar panels yes, wind power yes, wave power yes – these are all related to solar energy so use them all. Yet the solar energy isn’t an even or constant distribution, the equator and tropics clearly gets more sunlight and sunlight is only really useful during daylight hours. So we need to develop ways of locating solar arrays around the middle of the Earth, mostly. Once we have these arrays how do we trasport that captured energy from the equatorial zones to the polar zones and all those in between? We could build up huge banks of batteries and move them about. Yet they are heavy and if we did the maths we would probably find out that the efficiency of doing that is negative. We can’t wrap gigantic cables around the Earth. So the real trick would be to find another way of getting the energy from place to place.

Hydrogen Fuel cells – are these the silver bullet?

We could use the solar energy in the equatorial regions to crack water into Hydrogen and Oxygen – both these gases are light and easily moved around. Once at the place we need the energy we we use fuel cells to recombine them to provide electricity. The waste product of this process by the way is H20 – water. Now we don’t need to move the cells – just the gas. so the efficiency could be reasonable especially if we invest in the Hydrogen fuel cell technology and cycle. Clean, and efficient, not as good as trees, yet maybe not that far off. Interesting that the Sun ‘Burns’ hydrogen to produce solar energy, we can use solar energy to turn water into hydrogen and Oxygen, that we can then ‘burn’ to produce energy. Maybe we can learn lessons from nature, trees and sunlight – who would have come up with that.

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