Northwich u3a monthly meeting - July 2025
Our speaker for July was Professor George King who regaled us with facts and figures regarding ‘Solar Energy – its journey from the sun to your electric kettle’.
The solar power that reaches the Earth is 112, 000,000,000,000,000,000 watts. What the Earth receives in one hour from the sun is as much as everyone on the planet uses in one year. The difficult task is to collect it efficiently!
Solar power is a renewable and environmentally friendly energy source – i.e. a persistently flowing energy from a naturally occurring environmental source. As the life of the sun is 10 billion years plus, it will be available for a long, long time!
Solar radiation is the result of nuclear fission in the core of the sun, and the core itself is 10,000,000 degrees centigrade. Photons diffuse from the core in a ‘random walk’ and eventually reach the surface, thus producing sunlight. (This ‘random walk’ is not only found in physics but is also a fundamental concept in economics and finance – especially regarding stock prices.)
George talked to us about the difficulties concerning man-made fusion and told us a little of the early pioneers in this field, for example, Wein, Planck and Boltzmann. He also explained that the ‘Greenhouse effect’ was the atmosphere acting as a ‘blanket’ that retained heat from solar radiation.
Some examples of how to harness solar power were examined. The first and simplest was the parabolic mirror which could be a largish dish similar to a satellite dish, covered in foil. This could heat up to 150 degrees C and be taken camping. Jodrell Bank, at the Blue Dot Festival, did something similar so that everyone could toast marshmallows! The second was flat plate heaters on a roof which heat water to approximately 80 degrees C. (Apparently no-one in countries such as Cyprus and Australia pay for hot water because the homes have these. In the UK there aren’t many as the water only heats up to about 50 degrees.
George went on to talk about thermodynamics, heat pumps, solar power stations and photovoltaic cells. He also mentioned the stored energy in fossil fuels, fly wheels, capacitors and batteries. George continued with a reference to pumped storage hydro power, e.g. Electric Mountain, Llanberis but added that the UK would need 30 such mountains to sustain its needs. He concluded his talk with the idea of using Cheshire salt mines to store compressed gas.
This was an interesting talk about an issue important to all.
Come and join us at the next meeting on 20th August 2025 at 2pm in Owley Wood Recreation Club, Weaverham, when Jazz McPhail will let us in on the secrets of ‘Optimal Ageing’.