Text of talk to Llangynidr cubs (October 2014).
The sun is the ultimate source of (almost) all our renewable and sustainable energy. We can capture solar energy directly, with the solar panels on the roof here that convert sunlight into electricity. Or we can capture it indirectly from falling rain (as we do with the Talybont Turbine), or from the wind (as wind turbines do), or by burning or rotting dead plants and animals (as coal and wood fires do, and biomass digesters do). As long as the sun shines there will be plenty of energy to go round, but it can be expensive to convert it into the electricity and heat when we need them, so we need to be cleverer to survive on sustainable and renewable energy.
Most of the energy we use today comes from coal, oil and gas. These, too, are ultimately stores of solar energy – but in their case the remains of plants and animals that died and rotted away millions of years ago. These are called fossil fuels, and it took hundreds of millions of sunlight to make all the coal, oil and gas that we’ve been burning up for the last 200 to 300 years. We should have a couple of hundred years of fossil fuels left, but after that we’ll have to go back to capturing our energy directly from the sun, as we have for most of our history. But we know a lot more about energy than we did 200 years ago, so we should be able to figure out how to do that, and we’ve made a start.
Here in Henderson Hall, you can see some of the kinds of technology we will need. On the roof, there are solar PV panels. On a sunny day at mid-day, these produce nearly 8kW, and over the course of a year about 8000 kWh. That’s as much electricity as 2 houses consume in the same period. The Taybont Turbine produces over 30kW on a wet winter day, and over the course of a year about 250,000 kWh. Thats enough for about 60 houses.
A kWh is the unit of energy you see on your gas and electricity bill. It’s the amount of energy it takes to make about 36 cups of tea using an electric kettle. Our electric van which takes us up to the turbine uses about a kWh of electricity to drive 3 miles, the Twizy between 7 and 8 miles per kWh. So the PV panels on Henderson Hall roof produce enough energy for our van to do 24,000 miles.
But Talybont Energy is also about using the energy we have more efficiently, so that we will need to produce less of it. You can’t see it from the outside, but the Hall is now heated using an air source heat pump. That’s a machine that uses electricity to suck in outside air and cool it down. To do that, you extract heat which can be used to heat the inside of the hall, even though the air in the hall is warmer than the outside air! When the heat pump is heating the hall, you can go round the back and stand where the air comes out. You won’t be able to stand there for long, because the air coming out of the hall will be very much colder than the air going in. A heat pump is an energy efficient way to heat a building using electricity. It produces 3 times as much heat for a given amount of electricity as an ordinary fan heater would.