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Interesting comment about Solar energy. I have just had solar_PV cells installed and it has got me thinking about the viability of solar energy - bearing in mind that it generates nothing during the hours of darkness! I will make that the subject of a separate thread in the 'homes and gardens' forum when I have thought about it a bit more.
However during the day it is a ready source of quick energy - part of the problem with thermodynamic sources - especially where steam is the working medium, is the time taken to bring the power source on line - starting up a nuclear reactor or a steam turbine plant takes a long time hours/days which is why they rarely shut down - the alternators are kept rotating online - not necessarily generating much power - as 'spinning reserve, which is inefficient.
In practice, nuclear plants, when operating, usually operate at near maximum capacity, it is a more efficient use of nuclear fuel and still leaves some in reserve. Coal fired plants are the same, although there numbers are dwindling. The big advantage of gas fired generators - usually using gas turbines, is that they can be brought online from a cold start in a matter of minutes to meet an unexpected surge. Pumped storage systems can also provide a big surge of energy for a short time at short notice.
The usage of electricity is very predictable though almost on a minute by minute basis, and the distribution network has very accurate forecasts of energy consumption based on people habits, weather forecasts, television programming among other things. So having an immediate source of energy from fossil fuels is useful to meet peak demands.
So of the renewables - hydro-electric is probably the nearest thing to a continuos predictable supply - essentially solar in that it relies on the sun's energy to evaporate water which falls on higher ground to provide potential energy through gravity. Next there is solar pv, solar thermal and wind - all variants of solar energy. Solar_PV is great during daylight - doesn't have to be direct sun, so if the installed capacity is known on a regional basis, a forecast can be made based on weather predictions. Wind turbines are probably less easy to predict - and they are visually unattractive (IMHO) and solar thermal, while good for heating, isn't much use for generating electricity because the temperatures are too low. I have ignored heat pumps as they take power to operate and are good for heating, but not much good for generating electricity.
So you need a steady background source of power to meet the general background connected load, as that is required 24x7, it rules out direct solar and wind turbines, which leaves fossil fuel sources or nuclear. Fossil fuels (although I suppose technically solar!) are seen as polluting (although only releasing back into the atmosphere carbon dioxide that the original plant material extracted from it) so that really only leaves nuclear as a sustainable, and in theory limitless, source of energy, augmented by limited fossil fuel generators and solar pv and wind.
There are other options - biomass generators, wood burning but they all release CO2 to the atmosphere - the question is whether that CO2 can be re-captured by growing more trees - the problem is that it takes far longer to grow a tree than it does to burn it.
There are other technologies such as mimicking the photosynthesis process to harvest energy from the sun, bacteria based processes to do the same, but they are a long way from being mainstream.
So I would suggest that nuclear HAS to be major part of the UK's generation capacity, augmented by renewable energy as required and to suggest otherwise is just wishful 'green' thinking.
The other side of the equation is energy consumption - or the reduction of it. So a drive towards more energy efficient products - which doesn't mean the same as lower power - or a reduction in the use of high energy products. There is a problem there though - it takes a finite amount of energy to heat a cup of water to make a hot drink, or cook a meal, so there is limited scope there, although smoothing the load might make electricity transmission more efficient. Insulating homes to retain latent or exhaust heat from other processes (like coking, running appliances) would reduce energy consumption, and solar thermal has a role to play there - far more efficient to use the sun's energy to heat water directly than to convert it to electricity first so that reduces the requirement for electrical energy.
There are other aspects to using the energy we have more wisely. There are losses in the transmission networks, more efficient core materials in transformers would reduce losses there. Switched Mode Power Supplies in computers used to contribute to transmission losses in the electricity network because of their poor power factor, but legislation has improved that so power factor correction is built in. (as an aside - factories have to provide power factor correction for their installations so it is a minimum of iirc 0.8 to reduce power losses in the transmission network) so there are a lot of measures that could be taken, but they are expensive in the short term.
And finally - the elephant in the room - it is people that consume energy - whether it is 'primary' energy - food - or 'secondary' energy such as electricity - and the only way to control that in the long term is to control the growth of the world's population - because if we don't, nature will do it for us.
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Originally Posted by peterb
