The UK Low carbon Transition Plan (Cont'd)

[philpjuk100]

Hi there flyfisher,yes Im sure you are right,but as my house is listed rooftop panels are out and I dont wish to dig my garden up for a heat pump(although wouldnt a heat pump work on some coils of pipe sunk in the river?)This is really a project to keep me amused now that I have retired,Im on the outsde of a bend in the river where the current is too strong for a fit person to canoe against (although its ok for my fire pump powered "jet" ex sailing dinghy!) and it seems a shame not to utilise it,thanks for your interest,phil.

 

[Penners]

I wonder if it is because tidal power involves a lot of force, but slow current - if yiou get my drift. Maybe that means the conversion of kinetic to electrical power is inefficient - it doesn't turn many turbines (or the equivalent) very fast.

I also wonder if the twice daily rhythm of the tides, whilst predictable, means that max power production happens at certain times of the day and less efficiently at other times (eg change of tide). Also, it's quite hard to match power production to demand - it's either on or not, which is not the case with fossil-fuels which are more scalable.

The problem with tidal stream power generation is that the turbines have to be underwater. Makes them much more difficult to build and look after. If you have the capital to invest in renewable technology it makes sense to put it into something that has a proven track record from which you can be confident of the return on your capital. Wind wins hands down.

Well, those arguments seem to make sense, but has anyone considered the old tide mill principle?

You have a large pond that is filled by the rising tide. One second after high tide, a sluice gate is closed, impounding the water. Then, as demand dictates, this impounded water is released through a race to turn a mill wheel (or turbine blades, or whatever). The flow can be turned on and off as you wish, until the pond is empty.

Of course, once the pond water level has dropped to level of the tidal water, you have to wait for it to be refilled. But as the times of high tides vary considerably around our coasts, a grid system allows these "dead" periods to be planned for on a rota basis - which is not the case with wind, wave or solar power. And I can visualise a mechanism that doesn't need to be fully immersed in the water - like a mill wheel - thus avoiding the problems that Biff highlights.

As to the efficiency of the system, it seems to me that that tidal energy is available in such abundance that it doesn't really matter whether our devices are particularly efficient or not, so long as they are creating electricity from a constantly renewed resource.

I'm sure an expert would point out many flaws in this system for modern power generation, but I'm not sure what they are.

http://en.wikipedia.org/wiki/Tide_mill

Of course there are many other ways that tidal power can be generated - http://en.wikipedia.org/wiki/Tidal_barrage

Here's my favourite tide mill - Woodbridge in Suffolk:

 

[Moo]

If that's what a tidal system looks like, let's go for it! Beats wind turbines hands down.

 

[Flyfisher]

as my house is listed rooftop panels are out and I dont wish to dig my garden up for a heat pump(although wouldnt a heat pump work on some coils of pipe sunk in the river?)

Solar panels can be mounted at ground level, given enough clear sight to the sun. I've considered it as we're fortunate to have enough space, but it's not easy to find somewhere that isn't in shadow for large parts of the day unless the panels are sited a long way from the house, which brings it's own issues in terms of pipe runs and insulation. Not insurmountable, of course, but an added complication over roof-mounting.

As for heat pumps, from what I've read, a river is the best possible heat source as it's practically impossible to "over-extract" energy, which can lead to local cooling and even freezing in extreme circumstances. A river provides an effectively inexhaustable supply of constant energy.

So, plenty of options for retirement projects!

 

[philpjuk100]

Yes I belive that a heatpump using the river is the sensible option,The welsh assembly uses a heatpump using cardiff bay for its heat source although I have been told by a friend who did an energy audit for them that the assembly was heating up the bay for a while until they got it right! I will still be building the HMS waverley paddle geny first,and then looking at a heat pump after.Although the garden is big enough for panels I dont want to loose any of it and we have a lot of large mature trees in it casting shadows over large areas during the day (with a tree preservation on them!) and then maybe a wind turbine if I come into any money! you cannot have too much free energy!cheers phil.

 

[philpjuk100]

Great pic of the woodbridge tide mill,Im sure if we could build like that now there would be less "nimbys" or maybe not!,the power from water is a mass/velocity thing and you do not need a high speed turbine for mains frequency,you can use a gearbox which will increase cost and lower efficiency,but better is a multi pole alternator or even a water wheel alternators which are an axial turbine the blades of which are also the alternator rotor poles so the water which drives the alternator also cools it,They were used in the canadian hydro schemes in the 1930s,they proved to be unreliable but with modern insulation and technology Im sure could be improved.The problem then is to build barages,dam rivers etc with envoironmental problems,but then wind farms are appearing all over the place.The trouble with renewable schemes is that you require a lot to replace one coal/gas/nuclear power station,phil

 

[biffvernon]

The trouble with renewable schemes is that you require a lot to replace one coal/gas/nuclear power station,phil

The trouble with non-renewable schemes is that you require another planet to replace the one you've messed up.

 

[Moo]

Brilliant, Biff !!!
You're not just a poet and a craftsman, but a master of the bon mot.

 

[Schoolmarm]

The trouble with renewable schemes is that you require a lot to replace one coal/gas/nuclear power station,phil

The trouble with non-renewable schemes is that you require another planet to replace the one you've messed up.

:lol: :lol: :lol:

 

[FamilyWiggs]

The trouble with renewable schemes is that you require a lot to replace one coal/gas/nuclear power station,phil

The trouble with non-renewable schemes is that you require another planet to replace the one you've messed up.

Joke of the week (and boy did we need one!) to Mr Vernon.

Although, I'm coming round to the view that he isn't joking at all....

 

[Flyfisher]

Yes, very good, but Philip has a valid point about mass/velocity. For a given velocity, water has far, far more energy than wind. It it also far, far more reliable and predictable than wind; rivers tend not to stop flowing and tides tend not to stop rising and falling. Indeed, such is their reliability that they are surely more likely to be able to displace coal-generated units of electricity than somewhat fickle wind power?

 

[philpjuk100]

Yep good joke(tried a smiley but failed,Im better with a hammer than a keyboard!) The average max output of wind turbines being installed at present is 1.75MW at 15m/s wind speed as the output goes up with the cube of the wind speed the average output is far less,a powerstation like Drax is 4,000 MW no matter if the wind blows or not,so it would need a lot of wind turbines and cover a lot of land to replace a station such as Drax.Im also uncertain of the environmental impact of producing the turbines,Have you ever seen a blade close to? its BIG! made of grp(nasty!) and there are large foundations made of concrete(its that cement again)also lots of steel,aluminium and copper.Dont get me wrong I really like windmills and even built one for a static caravan but I dont think they are the answer,even if sited out at sea.but water power is more reliable,especially tidal,the tides go in and out even when the wind stops blowing.As technology moves on things may change,I dont wish to upset anyone but this is just the way I see it.My garden backs on to an unnavigable stretch of the trent and whilst most people see a pretty view I see energy! cheers,phil.

 

[biffvernon]

Oh really! It's not a question of choosing one or the other. We just don't have that luxury. We have to do it all and we have to do it now. In the short term, wind gives the greatest bang for buck - you start generating electricity just a few months after investing the capital and making a profit not long after that. Wind will probably always be under half the UK's electricity but we have a long way to go before that and a long way to go before the issue of wind variability becomes important. This is something that anti-turbine folk talk about a lot but it is not of concern to the power generation companies - the people who know. The Severn barrage could be a big factor but it will take a long time and a lot of money to build and, again, can only make a small, albeit significant, contribution to our total electricity demand. Tidal stream has a big potential but are still a long way from realization. The technical problems of working in a difficult environment are...difficult.

As the coal fired power stations are retired and new ones are not built when folk realise that clean coal is a mirage and nuclear is, as ever, too expensive and too late and too limited, somebodies lights will go out.

We have to manage the transition to a low-power and low-carbon carbon future. Our households have to use a lot less energy that they do now. It behoves each and everyone of us to work out what our personal contribution to the task.

 

[Flyfisher]

Biff, I'm not anti-wind turbine, I just can't imagine how they can be a significant answer to the renewables challenge. Fine, build as many as we can, but don't be fooled about their importance.

You answered two points about wind turbines yourself:

1. They are quick to build and profits follow very soon after. Privatised generating companies will naturally find this attractive as their objective is to make money for shareholders, not develop a strategic and secure energy resource for the country.

2. Wind certainly will always be under half the UK's generation capacity as it would be madness for it to be anything other than a small proportion. Imagine having half our generation capacity at the mercy of the wind.

I think your optimism that no more coal-fired stations will ever be built is, well, optimistic in the extreme. No government will let the lights go out while there is coal in the ground. I accept this would be a bad thing, but we have to be realistic. The best way to keep it in the ground is to make it unnecessary or too expensive and I don't think wind turbines can be much help in this respect. But tidal power is predictable for decades ahead; just the thing that's needed to help justify not replacing coal-fired capacity.

 

[philpjuk100]

There is so much "nimbyism" and resistance to change that people try to stop the building of anything,on our local TV news last week the prisoners "shop steward" from lowdham prison said that if they build a wind farm near the prison there will be riots! I find wind turbines attractive "works of art" but then again I see beauty in pylons so maybe Im a bit strange.There was also a bit on the prog about a farm being abandoned due to the noise from a wind farm on the horizon,strange how when you drive down motorways you see loads of inhabited farmhouses with all that traffic noise!phone masts,new towns,incinerators,tram lines,prisons,new roads, somebody must make a mint from all these appeals,phil.(up early,my bloody chickens woke me up! can I appeal?)

 

[biffvernon]

I just can't imagine how they [wind] can be a significant answer to the renewables challenge....it would be madness for it to be anything other than a small proportion.

Spain produces about a quarter of it's electricity from wind, rising to over 40% at times. See: http://en.wikipedia.org/wiki/Wind_power_in_Spain

Britain has a better wind regime than Spain.

 

[FamilyWiggs]

What is the carbon payback time for a wind turbine? I had heard that the amount of embodied energy in the construction (especially the concrete pad and service roads) was rather large.

Bit like the chap on the telly arguing that the electrification of the London-Swansea line would get rid of all the diesal pollution - yes but at the expense surely of increased generating pollution at the power stations?

 

[FamilyWiggs]

Spain produces about a quarter of it's electricity from wind

Penners will be along shortly Biff, to dispatch that set up line....

My best effort was "Must be all that chirozo they eat..."

 

[biffvernon]

What is the carbon payback time for a wind turbine? I had heard that the amount of embodied energy in the construction (especially the concrete pad and service roads) was rather large.

Bit like the chap on the telly arguing that the electrification of the London-Swansea line would get rid of all the diesal pollution - yes but at the expense surely of increased generating pollution at the power stations?

Carbon payback time for the Enercon 800kw turbines down my lane is about seven months

Electric trains involve much less CO2 emission than diesel. Power stations (even when burning fossil fuels) are almost twice as efficient as diesel locomotives. The electricity might be produced from a renewable source. Electric motors in locos run at about 95% efficiency are not nearly as heavy so can pull a bigger useful train load and don't have to carry their own fuel. It's a no-brainer. Should have been done years ago.

 

[Moo]

Talking of payback time, Jeff Randall in today's Telegraph gives a very gloomy answer to a query about solar panels (the sort, if I remember rightly, that heat the water supply). According to him it would be decades before the costs of installation+new boiler+associated pipework would be covered by any savings, and it would add no value at all to the price of the house.

I've not got the article to hand, and can't find it on the website, but it would be interesting to hear informed comments from the PPUK gurus.