ENERGY MATTERS

[Tizer]

Great post Tizer. I think you have just totally refuted James Lovelock's Gaia theory in one fell swoop. You are absolutely right of course, though I don't think I've ever seen it in print before.

Stanley's correct, David. I was quoting from memory of one of James Lovelock's books. He has been misinterpreted on his Gaia theory which he postulated simply to help people to understand the feedback mechanisms that stabilise Earth systems - he never intended people to really think that Earth was a goddess or a living organism. Rather that Earth behaves like a living organism in that both are controlled by feedback mechanisms. Lovelock is pessimistic about our ability to stop climate change, especially in view of the political will that would be required, but as he has got older (in his 90s now) he takes comfort in knowing that Earth and many other living organisms will carry on even if we humans perish. Perhaps rats will one day live in rat houses (no jokes please from German speakers), drive little rat cars, watch rat TV (Mickey Mouse!) and eventually build rockets to take them to Mars and beyond. And rat archaeologists will uncover astounding evidence that the Earth was once over-run by big aggressive animals that ran about on their hind legs and attacked each other (Humanosaurus Rex!), when they should have become peaceful and directed their energies into developing a better world.

[Tripps]

Maybe you're right, and I have to admit I haven't read it in detail, but -

Wiki says -
The Gaia theory posits that the Earth is a self-regulating complex system involving the biosphere, the atmosphere, the hydrospheres and the pedosphere, tightly coupled as an evolving system. The theory sustains that this system as a whole, called Gaia, seeks a physical and chemical environment optimal for contemporary life.[1]

You seem to say that Earth is indifferent as to what state it ends up in. That's the point I tried to make. Why should all the feedback systems be negative ones.

[Pluggy]

I wouldn't worry about oversized inefficient radiators (inefficiency in a radiator is arguably non existent since if the don't radiate the heat from the hot water very well, it means the boiler won't consume as much gas to keep the water hot). Over sized radiators is way better than having undersized radiators, it very easy to compensate for oversized (you turn the water temperature down and they behave exactly as a smaller radiator), besides changing the radiators there's nothing you can do if they aren't big enough. The radiators efficiency is purely an aesthetics thing, smaller radiators are more attractive, it isn't going to affect your gas bill to any extent. If they radiate more heat, the room warms up quicker and the boiler shuts off earlier, if they radiate less heat the boiler has to burn less gas - you don't lose any thing either way. What is important is the boiler efficiency, the control system (so the rooms aren't kept over warm) and the level of insulation in your rooms. There is absolutely nothing at stake by leaving old radiators in place when you renew a boiler assuming they aren't leaking and look acceptable. The positioning of radiators is more about personal choice than anything in the trade off between comfort and low energy use. For fuel efficiency you position them on inner walls away from windows, for comfort you position them under the window since its the coldest part of the room. I've had them both ways, and in general they are miles better under the window and you live with the extra fuel they use in exchange for the comfort and convenience (you can't put furniture in front of a radiator and you can't put it in front of a window either, so its better if its the same wall).

Usually the room stats are in the form of thermostatic valves on the radiators and you have an electrical/electronic thermostat that turns the whole lot on and off - thats all they are, a glorified on off switch and the positioning is open to controversy (there is a case for for putting it in the main use room and there is a case for putting it elsewhere, I'd favour on an inner wall in the main use room mmyself). On many modern boilers its a wireless battery operated job that can be put anywhere you like on a whim (this has disadvantages as well since you can't have a forced feedback system which tightens up the temperature spread that runs on batteries unless they are big batteries you change a lot) . If you have a reasonably set up (balanced) system there is a case against having thermostatic valves as well since they tend to fight for control with the main thermostat. If it works and there is reasonable control there isn't really a right way and a wrong way of installing a heating system, its all about choice and compromise.

Your water takes a long time to run hot, probably because you've got a combi boiler with no hot water cylinder, they are very efficient and very cost effective. Because they heat the water from cold as you use it there are compromises to be made (see earlier paragraph).

PS- I earned part of my BSc studying heating systems and thermal efficiency and I learnt my plumbing in a Royal Navy apprenticeship, where the boilers are the size of a small house and if you got a leak it could cut somebodies head off.

[Pluggy]

Strictly speaking, a domestic central heating system doesn't have a boiler (since it doesn't boil or if it does, it shouldn't) it has a calorifier.

[Stanley]

Good stuff Plugs and as you say, everyone has their own ideas. I recall that when the council did the big upgrade on East Hill Street a young lady told me categorically that my thermostat was in the wrong place and would have to be re-sited in the room I used most. I'm not sure whether she appreciated my short lecture on thermostat siting (!!) but in the end they left me alone. I came to the conclusion many years ago that the best place for the thermostat was in the place where the temperature was most stable and that individual room temperature was best regulated by adjusting the flow through over-sized radiators, ideally by thermostatic valves. Forty years ago when I put CH in Hey Farm my plumber told me I was mad when I said his plan for the system was OK but instead of single panel radiators he should make them all double. He said I'd use twice as much oil! So, my thermostat is on the upstairs landing, as far away as possible from any radiators and I still aver that this is the best place for it. The proof of the pudding is in the eating and it's significant that using the stove in the front room with the door open warms the upstairs enough to stop the thermostat coming on demand. The kitchen which gets no benefit from the stove is still comfortable with the heating off because it gets waste heat from the fridge, the PC, lighting and cooking. Under normal CH conditions, if the thermostat was in there the heating would have to be set much higher to get heat to the rest of the house. As it is, it is set at 17C and all is well. If I didn't light the stove the house would be comfortable but a touch too little in front room.
All boilers run at best efficiency when running at about 75% of ultimate capacity, that's why a properly installed combi boiler has two flame settings, moderate for heating and high for hot water. The most common installation fault with the older boilers is not having these differential settings enabled. Over sizing boilers and radiators doesn't increase overall gas usage, just speed of response. The key factors in controlling gas usage are boiler efficiency, insulation, draught proofing (Rate of air change) and your maximum room temperature room settings. The biggest wastrel in a combi system is the hot water tap in the kitchen. That's why I took the handle off my hot tap and whilst I know I am regarded as being slightly eccentric because I did this you soon get used to it and the savings are quite enormous.
But what the hell do I know about it, I have no formal qualifications..... Not even a driving licence these days!!

[Whyperion]

Unfortunately a slow running hot water tap is the thing I value most , for the kind of cleaning I often do.

The oversized radiators relate to the wallspace taken up , against which the furniture has to go ( the record collection does not take kindly to being placed in front of the radiators ). Ideally the heat from Freezer and Fridge would be useful in the Kitchen , but the newly installed units it was decided to increase the height of the lower cupboards ( giving the nice rat run underneath with plinths ) , and extend worktops over the fridge and frezeer. In My old 1950s kitchen I have full ground to worktop units ( sliding Doors of Hardboard running in cut out timber slots ) and the worktops at Fridge and Freezer Height ( in laws are in this property ) , as the both of them have decorative worktop style tops anyway. (As does the washing machine - if you dont mind the cutlery shaking on the spin cycle ).

[Tizer]

Tripps, I understand what you are saying and I think some of the problems with the Gaia theory have arisen in the past through mis-use of language. It's difficult to talk about Lovelock's Gaia idea without it being hijacked by people wearing sandals and sackcloth and worshipping at Stonehenge. For instance the word `seeking' gets interpreted as implying a divine intervention whereas I don't believe there is any divinity involved in the governor on a steam engine `seeking' to stabilise the system!

You ask `why should all the feedback systems be negative ones?' There can only be stability with negative feedback. Positive feedback would lead to a runaway state and be destructive, unless a negative feedback intervened to restore equilibrium. But of course there could be positive feedback, a shift to a different state, then negative feedback that doesn't restore the original state but maintains equilibrium in the new state. The present warming of the Earth's surface is a positive feedback from the release of extra CO2, leading to a disturbance of equilibrium (which I personally believe is responsible for the extreme and unusual weather patterns that are now experienced worldwide). So far we haven't seen any significant negative feedback to restore equilibrium and it may not occur until temperatures have risen too far for comfortable human habitation or unless humans themselves force a negative feedback (which needs to be very soon).

What I was trying to convey in my earlier post is that human life is not an essential component of Earth (or Gaia). We talk of saving the planet when we should be wondering whether or not the planet will save us. `Life' can easily exist on Earth at global temperatures that would preclude human existence, at least in any form that we would want to exist (it has done so in the past for long periods). However, life (living organisms) in more general terms have become over thousands of millions of years a characteristic part of the Earth system, playing a significant role in the checks and balances. For example, 3.5 billion years ago there was no oxygen in the atmosphere but photosynthetic organisms evolved and one of their major waste products was oxygen which eventually accumulated in the atmosphere and allowed larger, more complicated organisms to evolve. Also, this oxygen gave rise to the ozone layer that now protects life from 99% of the sun's harmful UV radiation. A different example is where living affects non-living - the microscopic algae in the oceans which produce a vapour that `seeds' the formation of clouds which are part of the `sunscreen' and are so important in transferring water to the land.

So the Wikipedia words "Gaia, seeks a physical and chemical environment optimal for contemporary life" are appropriate because that has been the equilibrium into which contemporary life has evolved as a partner. But we are now pushing towards a different equilibrium and it may not suit us. Billions of years have allowed very complex interactions and balances to develop between Earth systems, both living and non-living. Humans are the new kid on the block, we've only just arrived and we act as if we own the place. Perhaps its not surprising if the neighbourhood is getting disturbed!

[Tizer]

Pluggy, Stanley, Great advice, just what's needed - too many folk (like me) don't understand enough about their heating systems and benefit from this type of information. It reminds me of an engineer who was having a go at those companies who try to sell you new-fangled, `ultra-efficient' electric radiators and claim they use less electricity - "watts in equals watts out" (perhaps the engineer was Pluggy, I can't remember for sure!).

[Pluggy]

Pluggy, Stanley, Great advice, just what's needed - too many folk (like me) don't understand enough about their heating systems and benefit from this type of information. It reminds me of an engineer who was having a go at those companies who try to sell you new-fangled, `ultra-efficient' electric radiators and claim they use less electricity - "watts in equals watts out" (perhaps the engineer was Pluggy, I can't remember for sure!).

I plead not guilty to that one, but its absolutely true. I always regard electric heating as a waste, it is a very pure and expensive energy to produce, its a travesty just to turn it into heat which is the lowest common denominator of energy.

[Whyperion]

Electric heating has its place , no expensive Gas Mains , no bulky coal to haul or heave, fairly instant , transportable , a dry heat. Electric can be generated from waste or renewables. Clearly its not the answer to everying or all heating.

[Stanley]

There's a parallel argument to the sizing of energy converters like boilers and radiators. During quite a few miles flogging under-powered diesels to get about the country I worked out that fuel used depended on energy taken out and the thermal efficiency of the engine. It was cheaper to use an 'over-sized' engine running at its most efficient power range (Usually about 80% of total power) than flogging a smaller engine at maximum power. I learned this running at sixteen tons with a 90hp engine for years. Nowadays it is quite common for a 12 ton wagon to have 150hp and lower fuel consumption. My last wagon ran at over 32 tons with a 150hp Gardner LX, the same weight today would have over 400hp. The Gardner got away with it on fuel consumption because the design was the best in the world, (Rolls Royce spent millions developing the 'Eagle' diesel engine and in the end got to slightly better than 50% thermal efficiency, the same as the Gardner). I got 13mpg from the engine at that weight but my God you had to work for it! Small diesels in cars have been proved to have higher consumption that the equivalent petrol engine because of the different characteristics of the units when pressed hard. Industrial boilers were the same. The fuel gobblers were the under sized boilers working flat out on high flame. All things being equal, a big boiler running at 75% output was far more efficient and needed less maintenance. So, fit the biggest double panel radiators and make sure that the boiler has enough capacity to run the heating on 75% output. Check that the economy setting is enabled for the heating circuit, the only time the boiler needs high flame is for hot water. If you really want to waste energy, wash up under a running hot tap but remember that this is a third of your energy use!
As for electric heating, apart from the cost per unit of energy, this is wasteful because the ultimate thermal efficiency of the power at the meter is less than 20% due to transmission losses. The same applies to leccy used for charging batteries on electric vehicles. There is more, most of the big coal fired stations are on the East of the country so the prevailing wind takes the plume from the chimneys out to sea. That's why they have such high chimneys. At one time the Scandinavian countries blamed acid rain on these plumes but this has been disproved, the pine forests themselves are the main culprit.

[Whyperion]

Large radiators in small houses would overheat the rooms ( dependent on posistion of room stat and assuming no monitoring of return flow temperatures ). Small diesel engines at high revs are now preferred with the use of turbocharges. Electric vehicles could be charged from the solar panels reducing electric demand and are less polluting at street level.
Anyone got an answer to the cost of one new nuclear power station ( construction + operation + fuel + waste disposal + decommissioning ) over its useful life (25 to 40 years , lets assume uranium fission design ), compared with for equal power output the cost of solar arrays ( Supply , fix , maintenance to give 40 years total life ).

[Tripps]

There's a problem there - as seen from Pluuggy's graphs - in the winter when demand is high, his panels only contribute (being generous) from about 11.00am to 3.00pm.

[PanBiker]

Anyone got an answer to the cost of one new nuclear power station ( construction + operation + fuel + waste disposal + decommissioning ) over its useful life (25 to 40 years , lets assume uranium fission design ), compared with for equal power output the cost of solar arrays ( Supply , fix , maintenance to give 40 years total life ).

No price on this at this moment in time as no one has yet figured out how to fully and safely decommission. Windscale is testament to this as it is still burning out of control over 60 years after the event. Bury it in in concrete is not really a solution in my book.

[Big Kev]

Large radiators in small houses would overheat the rooms ( dependent on posistion of room stat and assuming no monitoring of return flow temperatures ).

Wouldn't be an issue with radiator stats. I don't have a room stat in my house, the rads call for hot water when the radiator stats open. Maximum water temperature, in the system, is controlled by the stat in the boiler.

[Pluggy]

There's a parallel argument to the sizing of energy converters like boilers and radiators. During quite a few miles flogging under-powered diesels to get about the country I worked out that fuel used depended on energy taken out and the thermal efficiency of the engine. It was cheaper to use an 'over-sized' engine running at its most efficient power range (Usually about 80% of total power) than flogging a smaller engine at maximum power. I learned this running at sixteen tons with a 90hp engine for years. Nowadays it is quite common for a 12 ton wagon to have 150hp and lower fuel consumption. My last wagon ran at over 32 tons with a 150hp Gardner LX, the same weight today would have over 400hp. The Gardner got away with it on fuel consumption because the design was the best in the world, (Rolls Royce spent millions developing the 'Eagle' diesel engine and in the end got to slightly better than 50% thermal efficiency, the same as the Gardner). I got 13mpg from the engine at that weight but my God you had to work for it! Small diesels in cars have been proved to have higher consumption that the equivalent petrol engine because of the different characteristics of the units when pressed hard. Industrial boilers were the same. The fuel gobblers were the under sized boilers working flat out on high flame. All things being equal, a big boiler running at 75% output was far more efficient and needed less maintenance. So, fit the biggest double panel radiators and make sure that the boiler has enough capacity to run the heating on 75% output. Check that the economy setting is enabled for the heating circuit, the only time the boiler needs high flame is for hot water. If you really want to waste energy, wash up under a running hot tap but remember that this is a third of your energy use!
As for electric heating, apart from the cost per unit of energy, this is wasteful because the ultimate thermal efficiency of the power at the meter is less than 20% due to transmission losses. The same applies to leccy used for charging batteries on electric vehicles. There is more, most of the big coal fired stations are on the East of the country so the prevailing wind takes the plume from the chimneys out to sea. That's why they have such high chimneys. At one time the Scandinavian countries blamed acid rain on these plumes but this has been disproved, the pine forests themselves are the main culprit.

Got to disagree on a couple of points. A small diesel engined car is more economical than a petrol under any conditions. They both are at their most efficient close to maximum power, the petrol more so due to the lack of vacuum in the inlet manifold at high power, the diesel doesn't have a vacuum at any power. A turbo improves the efficiency of a diesel, it makes a petrol thirstier. Its easily checked out, pick a car, any car available with a petrol and a similar power diesel and get the gm/km for each and the urban and extra urban MPG. The new Skoda Fabia with the 1.2 litre 69 PS Petrol emits 128 Gm/km, the 1.2 75 PS turbo diesel emits 89 gm/km. The MPG figures are in line with those figures. The increased cost of the diesel means you have to either keep the car for a while and/or do a lot of miles to recoup the extra.

The national grid transmission losses average 8% now, so with a CCGT power station at peak efficiency you'll be getting around 50% of the thermal energy (around 33% with a good coal plant). Since the grid was first put up in the 20's and 30's the losses have dropped dramatically. The upping of the transmission voltages from 133,000 to 400,000 decreases the losses by a factor of 10. Not all the grid runs at 400,000 however so the losses average out at 8% of the total generated. Not the horror story it once was. Its still better to burn gas at 80% + efficiency for space and water heating.

Solar panels are bottom of the list for cost per Kwh, they make off shore wind and nuclear (the next two up) look cheap. Having said that there are plans for a large solar (PV) farm in Spain starting in 2014 which will be viable without subsidies - they'll have to sell it directly at retail prices rather than export it however. The sunny days per year are lot better in Spain than here.

Working on present retail electric prices, my panels would pay for themselves in about 25-30 years assuming they didn't need any maintaining in that time.

[Pluggy]

There's a problem there - as seen from Pluuggy's graphs - in the winter when demand is high, his panels only contribute (being generous) from about 11.00am to 3.00pm.

On a really dark winters day, they sometimes don't generate anything all day. They share the problems all renewables have, they need backup capacity to take over when the sun isn't shining, there's no wind and the sea is becalmed. If you're serious about CO2, I can't see a way past nuclear in the medium term. Thorium fission possibly in the not to distant future and nuclear fusion maybe beyond that. If they hadn't had the preoccupation with making Plutonium for weapons in the past, we would probably have viable Thorium reactors now.
,

[Whyperion]

I was making the point that availability of useful solar is about the same as nuclear. Gas is more efficient burnt as a domestic/industrial fuel rather than for electricity generation ( thus over-riding Cameron's dash for gas ) . Logically the country needs a balanced power management strategy, involving solar and other renewables ( the biggest cost with solar is surely the labour cost involved with construction of the panels and affixing , something that would appear to be a rather useful thing to go for with 2.3m unemployed hanging around ), also CHP if the particulates problem can be cleared up. and demand management , we seem to be increasing the desire for electricity ( at the corporate and local governmental level ) without seriously looking at ways to permantently save 10 to 20% of present day consumption.

[Stanley]

Ah well, what the hell do I know about heating and engines anyway. After all, I am old and out of touch with everything!

[Whyperion]

I rather like a domestic gas fire , with radiants and convection sections , seems to keep mums flat warm enough , but...

With domestic space heating , as heat rises , and a fair proportion of houses in Barnoldswick have higher ceilings than other places. One ends up with wasted heat at ceiling levels ( so arguement for dropped false , insulated ceilings ), and even then one gets overheated at head level , whilst ones feet at ground level are too cold ( ok thermal socks and slippers help resist this ). Again if fitting I would prefer the blown gas fired or mini radiators at skirting board level. Stanley wasn't your conclusion on lorry diesel engines as a result that manufacturers often made the units to be capable of 120% of the normal expected load , whilst making them efficient at 100% of load , hence appearing that around 80% of rated max gave best efficiency ? (Ideal for trunking routes , but for many stop-start urban delivery situations doesnt this size of engine start to become inefficent ? )

[Pluggy]

Diesel engines nowadays are rated to the onset of black smoke, but the power continues to rise way past that point, so its quite possible to get a lot more power out than rated. Watch a tractor pulling competition, the engines are more often than not belching thick black smoke to get as much power as possible out of the engine. Needless to say it isn't environmentally friendly or even good for your health, diesel smoke is nasty stuff. The efficiency drops off once they start producing smoke. A turbo diesel will often produce smoke when accelerating until the turbo starts doing its job and forcing more air into the engine and improving combustion.

[Stanley]

Dead right Plugs. Every Gardner engine came with a set of results from running a power/consumption curve on the test beds. This was done by the fitter that built the engine. Due to good design and high manufacturing standards their engines gave a flat maximum torque reading from very low in the revolution range. The injector pump was calibrated to maintain this curve with no smoke. It was this good combustion control that gave them such low fuel consumption. The long stroke design meant that they achieved these characteristics at lower RPM than other engines. The 150hp LX had 1750 maximum revs. In good condition the engine only made smoke on start-up, this was because the governor controlling the injector pump was designed to give maximum fuel at start-up. All modern diesels are made to run clean at maximum power, the ones that smoke are either badly maintained or have been modified. When I was in the States I noted that their big diesels made a lot of smoke and nobody seemed to be concerned. Probably a consequence of cheap fuel. One other unique feature of the Gardner was that the governor linkage design incorporated an adjustment to the timing of the pump. As you lifted your foot off the injection was retarded and you got more power. Very strange feeling when you were slogging up a hill when power increased as you lifted your foot slightly. Amazing the number of drivers that never knew this, they hadn't read the instructions!

[Stanley]

New use for my stove. Slow-cooking food all day at a slow simmer. Brilliant!

[Pluggy]

New use for my stove. Slow-cooking food all day at a slow simmer. Brilliant!

This comes back to 'old age and freedom' I can't see mrs pluggy taking kindly to cooking in the living room.

Heres the effects of PV panels over a month :






Nice backwards capable main meter says we've used 108 Units, actual Import (what we should be paying for) 240 Units. Actual usage I don't have figures for which is what the extra meter in the bottom picture is for . Around 10 units a day would give 310 Units. We generated 200 units in that same month (not visible on picture). The new meter is what we use, including imported and generated electric so in future I'll have exact figures for that too. Not a major outlay, the meters are refurbished ones off ebay. If in the future I get a non backwards main meter which shows import I'll swap my import meter round to an export meter (after I've checked the accuracy of the new one) The three meters in the picture are accurate to within 1% of each other when we're not generating. Having two meters monitoring the same thing can be used as a check. There are horror stories about peoples bills doubling and trebling when they get a new meter fitted and the new ones aren't accurate.......

[Tizer]

We are very pleased with our 1.6TDi Golf, the first diesel we've owned. It gives us 60mpg on a 30-mile run compared with 40mpg at best from our previous car, a 1.8 petrol Focus, and the Golf has more torque. The Focus always pulled well but the Golf does even better and is marvellous between 1000 and 2000rpm, making overtaking safer.

Whippy, gas has a problem - leakage from pipelines. A lot of gas is lost, which is not only a waste but it's also a greenhouse gas and more strongly so than carbon dioxide. On the radiator thermostatic valves, I agree with Kev and I can't imagine having a central heating system without them now - unless you have only one radiator! We keep our TRVs at different settings to suit the room use and adjust them as needs be.

Unfortunately, there has been a lot of mis-selling of solar heat and power systems to consumersand the regulator is trying to tighten up on it. We saw an example recently where the panels were installed in winter when the trees were bare of leaves - any time now the PV panels will stop working as the leaves come out on the deciduous trees that will shade the house. Another problem seen recently - a solar system has been installed beneath a TV aerial and it's now covered in bird droppings!

Here's a couple of odd questions that someone might be able to answer for me. First, if you set up a PV panel behind a double-glazed window will it work, and if so, will it be as efficient as if there was no glass in that window? In other words, is the light that comes through a double-glazed window as effective at generating electricity from a PV panel as ordinary light falling on the roof?

Second, what proportion of the energy consumed by a 100W light bulb is converted to light and what proportion to heat? This question came to mind when I remembered the story of Mrs Tiz's father making a bed warmer. He was in his early teens at the beginning of WW2 and lived at the Gravesend sewage plant where his dad was engineer, so he was evacuated to Beccles, Suffolk (via paddle steamer!) and lodged with an elderly widow in a cold cottage. Being the son of an engineer, he wired up a light bulb in a metal can so that the old dear could warm her bed before retiring (and it didn't burn the house down!).