BMW falsehoods

[Kalee20]

Next time you drive along a motorway in your electric car and see a coal fired power station you are looking at your own exhaust pipe.
To me electric cars will keep city centers free of soot but overall there is little environmental benefit.

Partly agree, partly not!

Electricity for electric cars does have to be produced, obviously. And there is distribution losses.

However, a stationary power station has the potential to be far less polluting than a petrol engine. It can have flue gas filtration, electrostatic particle catchers, etc etc which is bulky and heavy but does not have to be lugged around. Whereas the car is limited to what can be fitted, space and weight-wise.

[Murphyv310]

Agree and disagree too Kalee.
While I agree with what you say at the power station we need to take into account the processes required between the harvesting of the raw fuel and its eventual arrival at the power station.

[Refugee]

There are a whole lot of improvements that could be made.
First the power has to be harvested and in many cases physically carted to a power station.
Before we had motors to power transport it was found that mined products could be carried by horse drawn power in greater quantities if the rolling resistance was reduced by running the cart on smooth hard surfaces and then later rails and later still with steam power. Coal was transported to points of use including power stations in this way.
Then you have distribution losses that can easily demonstrated by connecting a volt meter to a metal building or fence that is located under power cables. Some people have been able to harvest small amounts of free energy this way.
The biggest saving in transport energy would be to put trucks onto flat bed trains for the larger parts of there route while the drivers take there formal rest periods on the train. Trains have a much lower rolling resistance and the land usage would not exceed the amount used to widen motorways to accommodate the trucks.
Solar is useful if it is being used to charge something like a lawn mower provided the panel is on the garden shed roof. The brighter the sun shines the faster the grass grows while the battery is charging at the same variable rate .

[Kalee20]

Refugee raises an interesting question - 'coal transported to the point of use...'

If you define 'point of use' as the point where the energy is required, one extreme is transport it as coal, efficiently on rails, to very close to the point of use, burn it in a power station, get the electricity available with virtually no distribution losses at the point of use. The other extreme is to build the power station at the coal mine, so there's no transportation of coal, no railway needed - and the electricity itself then gets to the point of use by long wires.

Which, I wonder, is the most energy-efficient?

I also like the solar-charging of the lawnmower batteries where the grass growth and battery energy are in a relatively constant ratio. Very elegant, and good thinking!

[Refugee]

You have to be careful with long wires as they act like aerials and radiate some of the energy.

[ppppenguin]

The whole nature of generation and distribution will be shaken up in a big way over the next 20 years or so. As solar and wind become cheap, while large scale storage becomes a reality. As all that starts to become economic, then burning stuff to generate electrcity will start to look very expensive and outdated.

Let's face the fact that none of us really wants to burn stuff to keep the lights on. Except the producers of gas and other burnable stuff. What we want is lighting etc at low cost. When low cost also means not burning stuff it's win all round.

There's lots of embodied energy in concrete. Making cement is energy intensive and appraently there's another problem in the UK as they used to use a lot of blast furnace slag as a cheap ingredient. Now that's in short supply and that pushes up the price of cement. But more architects are using engineered timber solutions for buildings. Precision cut at the factory and slotted together on site. Quick, easy and lower embodied energy than concrete. Feasible for multistorey up to a point. Fire isn't a great problem as once it's charred on the outside large lumps of wood don't burn very well.

(i ought to add that some of this comes from my partner, Ruth, who's a journalist working in the fields of architecture, construction and landscape)

[Murphyv310]

Of course water can be heated by the suns rays by fitting heat exchangers to rooofs. The heated water flows by thermo syphon to a storage tank, valves stop the water cooling by back flow to the heat exchanger at night or if it gets cloudy. I've come across this system twice and even up here it can raise the water temperature to 70c in summer and on a bright winters day over 30c. So having the heat exchanger water system, solar panels and even a 1kw wind generator can all add up to near self sufficiency in energy.
I'm considering a small wind generator to add to my home built solar system.

[ppppenguin]

My total leccy usage is about 2000kWh/year plus whatever my PV generates and I actually use, say another 800kWh. More PV, a little wind energy and a suitably sized battery would get to self sufficiency. Except that it would be a big battery to allow for the sun not shining much in winter. Not viable yet for me when there's a grid conenction and power that's not too expensive.

Solar DHW is entirely practical but really needs a south facing roof which I don't have. My PV faces just south of west which isn't ideal but good enough. In sunny countries solar water heating is cheap and simple. With an immersion heater backup for those occasional days when there's not enough sun.

[Terry]

Regarding Ref's points about transport costs, this has been a problem since the inception of power stations but was dealt with in a simple but efective manner - by building as many power stations as possible on coasts and navigable rivers.

Take the Thames, for example: apart from the former Battersea power station, there were also Bankside, Northfleet, West Thurrock and Tilbury to mention  a few. The reason? Water transport was - and probably still is - the cheapest way of transporting coal. One vessel could haul a string of barges from the coal mines in the North East down to the Thames in massive quantities at very little unit cost.

This should not, of course, be confused with the practice of building nuclear plant on the coast, which is done for entirely different reasons.

On the subject of nuclear, now that they are no longer an excuse for producing weapons grade products, I don't see why there is still so much hostility to them. The half life of the most dangerous by products can be measured in fractions of a second so that they degrade rapidly. The low level waste can be encapsulated in small amounts in glass and used as ballast in road building, for example, where the radiation producing element is so thinly distributed that the level of radiation is far below anything that could be vaguely considered dangerous to life - unlike the granite areas of this island that give off copious amounts  of Hadon gas with radiation levels significantly above the danger limit. Yet I haven't heard of hot spots like Cornwall becoming becoming open wasteland ...

[Terry]

In my previous post I should, of course, have excluded Bodmin Moor (and Dartmoor in neighbouring Devon) as, despite being areas of high Radon leakage, they could be described as wasteland in the main.

Having done a bit more research, I note that parts of Lincoln also have maximum Radon levels recorded - possibly because it is a big lump of rock with a castle perched on top! Actually, the castle itself is in the second highest band whereas, if I visit Wetherspoon's for a pint or four, I note that, being virtually at sea level, it is in the area of lowest recorded levels as is North Hykeham, so I can go to sleep in the sure knowledge that I'm not going to glow in the dark!