Extinction Rebellion, ongoing disscussion.

[adam2]

If it can not be changed back to 24 volt, and used with a 3 wire system, then I would look for some very thick cable.
70mm should suffice and may be affordable at scrap prices.

[adam2]

Lesson three, again not a formal lesson but more of a round table discussion. Different means of generating electricity by burning fuel.

1) Burning coal or other fuel to raise steam that works a reciprocating steam engine. Largely obsolete, low efficiency, possibly worth considering in an emergency, esp if the engine already exists. Typical efficiency varies from 1% up to about 10%, maybe 15% under optimum conditions. Needs a lot of water.

2) Burning coal or other fuel to raise steam that works a steam turbine. Still in widespread use, but falling out of favour. works best on a large scale, efficiency from about 15% up to 35%. Little hope of improvement. Needs a lot of water.

3) Burning gas or liquid fuel in a gas turbine. Very popular, quick starting, not that efficient. no water needed. Low capital cost, can start and run unattended. Some types are dual fuel, burning natural gas normally but with light oil as an emergency alternative.
3b) As above but with a waste heat boiler that operates a steam turbine, highly efficient, 45% typically, has reached 50%. Very popular.

4) Diesel engines. Quick starting, can start and run unattended. fair efficiency in large sizes, usually needs no water.

5) Petrol engines poor efficiency, quick starting, dangerous fuel. Cheap, recommended for short term or emergency use.

[adam2]

We then moved on to alternatives.

1) PV. simple to use and install, from a few watts up to megawatts. Much cheaper than previously. Manufacture of PV modules is a high technology operation. No moving parts long lasting and reliable.

2) Solar thermal. Useful when a lot of warm water is required, such as for hotels, hospitals, industrial laundries, heated bathing pools. Low tech.

2b) Solar thermal for steam raising to work a steam engine. Largely displaced by PV and electric drive.

2c) Solar thermal for desalination of sea water, low tech and user repairable, works fine but has been displaced by PV and reverse osmosis plant. Needs a lot of land.

3) Wind power, used on a large scale, domestic size turbines only worthwhile in very windy locations. Gave example of domestic wind turbine installation.

4a) Large scale hydro power, capital intensive, limited chance to expand in the UK as the best sites are already used. Note that the water is not consumed but is still available for other purposes. Dangerous if the dam breaks.

4b) Micro hydro. Has a lot of potential. Cost very variable.

5) Human powered generators. Excellent for short term or emergency needs. Limited to about 100 watts for cycle type machines, or about 15 watts for hand crank types.

6) Peltier generators, very low efficiency but this matters little if the waste heat is rejected to a room that needs heating in any case from a stove.

7) Fuel cells, still hugely expensive but show promise. Still need fuel despite often being listed as an "alternative" Silent. Possible "doom prep"

Disposable batteries, these ARE fuel of a type despite often being considered as an alternative. Simple, reliable, and safe. Hugely expensive at from £50 to £500 Per kilowatt hour compared to about 15 pence from a utility company. Useful for emergencies, for portable use, and economic for very small loads of up to a few watts short term or fractions of a watt long term.

[clv101]

6) Peltier generators, very low efficiency but this matters little if the waste heat is rejected to a room that needs heating in any case from a stove.

How many watts can you get from a hot plate on a wood stove? 5-10W for a half decent LED lantern?

Datasheet for this gives a general idea, cooling the cool side might be tricky though.
https://uk.rs-online.com/web/p/peltier-modules/7650019/

[adam2]

Yes, a peltier generator atop a wood stove and rejecting the heat from the cold side into the room air can achieve at least 10 watts and up to 15 watts in favorable circumstances. Some units sold on line claim greater outputs but I suspect chinese watts in such cases.

Note that whilst the efficiency is only about 1% to 2% that this does NOT imply the waste of 98% or 99% of fuel burnt. 2% into electricity and 98% into heating an otherwise cold room is a good result.

By water cooling the cold side of a peltier generator, greater output can be obtained, but this removes a lot of heat from the space that one wishes to heat. The pump consumes electricity, adds another point of failure, and plumbing is vulnerable to leaks and to freezing in severe weather.

Only worthwhile if you have a use for a lot of lukewarm water. Posibilities include a second hot water cylinder in which cold mains water is preheated to say 35 degrees before passing into the second tank for heating to say 60 degrees.
Or limited central heating by use of HUGELY OVERSIZED radiators through which the warm water pumped. FIVE times the normal radiator area is about the minimum, bigger is better.

Both the above involve considerable capital cost and complication for marginal gains.

[kenneal - lagger]

Or underfloor heating instead of larger radiators.

[adam2]

Or underfloor heating instead of larger radiators.

Yes that would work. Probably only worthwhile for a relatively large installation.

[adam2]

Lesson four, again not a formal classroom type lesson but more of round table discussion.

Largely about older versus more recent technologies, there being a general belief that if it was old then it must be better.

Noted that steam engine drive and line shafting power distribution in factories is now almost extinct. Low efficiency of reciprocating steam engine noted, and losses in line shafting. Almost always replaced by individual or group electric drive of machines.
Merits of steam power as being relatively low technology, but these days unusual.

Briefly mentioned the famous American "liberty ships" of the last war. Driven by an obsolete type of reciprocating steam engine, long after the general use of steam turbines. Largely because the older type of engine was easier to make and needed no reduction gears, production of which was a bottleneck in wartime.

Briefly mentioned steam railway locomotives, largely extinct in most countries apart from limited heritage use. Fireless safety steam locomotives used until recently in munitions stores, petrol depots etc.

Moved on to traditional water wheels, interesting heritage, but insufficient power for most modern applications.

Moved on to traditional windmills, simple and low technology, need a lot of labour, not suitable for unattended operation.

Conversation diverged on to more general heritage versus modern.

[adam2]

Latest protests in London by XR https://www.bbc.co.uk/news/uk-england-london-58306278

Seems fairly low key.

[kenneal - lagger]

One of the leaders of the protests publishes on Facebook every day and he is saying that the press are playing down the protests to make XR look ineffectual. That wouldn't suprise me at all.

[kenneal - lagger]

This is a good and long, 6 mins, report from Channel 4 news last night on the London protests.

One of the "members of the public" interviewed at the end for their reactions to the protest was probably an XR supporter as I know him from the AECB and that he lives in Llanidloes in mid Wales.

[Potemkin Villager]

Latest protests in London by XR https://www.bbc.co.uk/news/uk-england-london-58306278

Seems fairly low key.

"The Metropolitan Police said it would put a "significant" operation in place to manage the protests over the busy bank holiday weekend but acknowledged the activists' "important cause""

So XR seem to not be regarded as a dangerous terrorist organisation, for now anyway.

[cubes]

Wouldn't they have more success using the same tactics fossil fuel companies do? Lobby politicians (with donations to their party) and assure them of luctrative well paid 'jobs' after they finish politics?

[kenneal - lagger]

Wouldn't they have more success using the same tactics fossil fuel companies do? Lobby politicians (with donations to their party) and assure them of luctrative well paid 'jobs' after they finish politics?

If only, cubes!!

XR is pushing the International Court to prosecute politicians for the murdering of hundreds of thousands of children because of their failure to act on Climate Change. They've been sent by the judges who they lobbied to the Prosecutors office and are awaiting a reply from them.

[adam2]

Protest and blockade underway at an oil refinery.
https://www.bbc.co.uk/news/uk-england-h ... e-59074870

Protesters have climbed an "oil silo" I thought that silos were used to store granular materials such as grain, fertiliser, cement and the like. And that oil and other liquids were stored in tanks. Probably too fine a distinction for todays reporters.