http://citycyclingedinburgh.info/bbpress/ CityCyclingEdinburgh Forum » Topic: Electricity en Sun, 31 May 2026 20:59:50 +0000 http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213579 Mon, 07 Mar 2016 10:02:35 +0000 chdot 213579@http://citycyclingedinburgh.info/bbpress/ <p>"</p> <p>EDF has confirmed that its finance director has quit ahead of an expected final investment decision on the £18bn Hinkley Point nuclear power plant. </p> <p>Thomas Piquemal stepped down because he feared the project could jeopardise EDF's financial position, according to reports.</p> <p>"</p> <p><a href="http://www.bbc.co.uk/news/business-35741772" rel="nofollow">http://www.bbc.co.uk/news/business-35741772</a> </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213538 Sat, 05 Mar 2016 23:03:42 +0000 acsimpson 213538@http://citycyclingedinburgh.info/bbpress/ <p>@HankChief, Yes you are right of course the sun profile can lead to very different daily outputs from different systems. Our friends who have a lovely south facing roof generates about double what our eastish/westish/southish one does but on a cloudy day we can generate more than them due to having panel optimisers in our system.</p> <p>When I looked last November Edinburgh appears to get more hours of sunlight before the solar Noon than after it due to a combination of factors. However the average home is likely to use more power in the afternoon which again makes it very hard to compare actual savings from systems.</p> <p>One thing I forgot to mention in my earlier email is that if you are replacing a roof then Solar can still have an early payback. The company who installed ours are now specialising in building solar panels into a roofs. This saves on the cost of labour and reduces the materials needed thereby saving in the initial cost and reducing the payback time. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213501 Sat, 05 Mar 2016 08:14:49 +0000 HankChief 213501@http://citycyclingedinburgh.info/bbpress/ <p>@ac you have to be slightly careful about comparing readings between systems. </p> <p>I know someone local who had an identical system to our installed and on any given day we would get different results depending on it being a sunny morning or sunny evening due to alignment of our systems being different. Over the year it evened itself out though. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213500 Sat, 05 Mar 2016 00:34:32 +0000 acsimpson 213500@http://citycyclingedinburgh.info/bbpress/ <p>@Bbaldycyclist, the cuts were reduced to "just" 67% rather than the full 83%. It doesn't sound like much but based on my back of an inner tube packet calculations might mean that if you have a perfect roof a solar PV setup can still pay itself back. Of course it also means that Solar is now vastly less subsidised than Nuclear and IIRC coal/gas.</p> <p>Payback now depends on being able to efficiently use most of the generated power and even then is now in the 16-20 year range rather than 5-10 as it was before the cuts. The efficient use part is tricky as it requires you to have an existing load which as Hankchief says that can be a lot of energy in the middle of summer, possible for a commercial installation but unlikely in a domestic one.</p> <p>Diverting the power to heat hot water, or indeed anything else which can be heated with gas does save money. However assuming your alternative is to heat with gas it can only be considered a saving against the KwH cost of gas which might be around a third of the cost of Electricity.</p> <p>If you don't worry about the time for the capital to pay itself back then you should be able to get an actual cash return somewhere in the region of 3-4% and if you were to have space for a larger array (up to 10Kw) you might be lucky enough to get more as the FIT now doesn't change below that.</p> <p>We installed 3.99Kw of panels on a sub optimal roof in December so don't know how much we will generate in the summer yet, although based on today's production I assume Hankchief's roof is also not perfectly shaped so perhaps somewhere similar to his. We decided to add an immersion heater which cost despite only costing £150 may take several years to pay itself back. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213495 Fri, 04 Mar 2016 22:01:31 +0000 HankChief 213495@http://citycyclingedinburgh.info/bbpress/ <p>We have a 4kw PV set up.</p> <p>In the depth of winter we get some days we get barely 0.5kWh - today was 2.6kWh.</p> <p>Come the summer though we get days of up to 30kWh.</p> <p>Overall it is delivering as expected and is paying back well.</p> <p>I totally recognise that it only made financial sense for us because we got the lucrative FIT rates before they were cut. Not sure it's still the case. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213489 Fri, 04 Mar 2016 20:55:07 +0000 I were right about that saddle 213489@http://citycyclingedinburgh.info/bbpress/ <p>edd1e_h</p> <p>No need to apologise. Books are for dismantling. I just happened to be reading that one and thought it apposite.</p> <p>I like the guy's approach to getting orders of magnitude correct. That's how I approach problems myself. I'm not sure he's likely to drop too many techno-clangers given that he was chief scientific adviser to the Department of Energy and Climate Change and professor of engineering at Cambridge. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213488 Fri, 04 Mar 2016 20:54:49 +0000 Baldcyclist 213488@http://citycyclingedinburgh.info/bbpress/ <p>We looked at Solar Panels very recently (Dec), trying to get them installed before Mr Osborne made them 83% less attractive.</p> <p>You can by a diverter for as little as £300 which will divert any unused PV electricity to water heating during the day.</p> <p>The benefit comes as you still get the FIT, as well as the free hot water. The FIT is assumed based on the size of system / location / amount you generate, NOT the amount you actually use. It's not actually measured in any way...</p> <p>Until SMART meters are installed you get the double benefit. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213484 Fri, 04 Mar 2016 18:41:43 +0000 crowriver 213484@http://citycyclingedinburgh.info/bbpress/ <p>Solar heated water very popular a bit further south in Europe, where the sun is HOT.</p> <p>Makes sense on a new build, or if you're redoing the roof/converting the loft space. Otherwise maybe a bit dear still. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213481 Fri, 04 Mar 2016 17:00:19 +0000 steveo 213481@http://citycyclingedinburgh.info/bbpress/ <p><em>I gather that people get the best results here by using PV to drive an immersion heater, </em></p> <p>Very odd, I guess that is instead of selling any excess back to the grid. Looking at the relative costs of a PV or solar thermal I can see why one would chose a PV set up. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213479 Fri, 04 Mar 2016 16:47:24 +0000 Dave 213479@http://citycyclingedinburgh.info/bbpress/ <p>We have a perfect south-facing roof for panels so I have done a little research. I gather that people get the best results here by using PV to drive an immersion heater, strange as it may seem.</p> <p>I have considered trying DIY water heating (or preheat) as we already have a tank, but life has been too short so far. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213474 Fri, 04 Mar 2016 16:34:06 +0000 steveo 213474@http://citycyclingedinburgh.info/bbpress/ <p><em> big rocks on wires down the middle of them and adapting the blade-turbine mechanisms to be able to switch to winding the big rock up</em></p> <p>I think it would have to be a pretty enormous mass to store any meaningful amount of the turbines time. 1t @30m is still only about 80wh which would be a few moments of time for a large turbine.</p> <p><em> isn't solar water heating really quite viable even here in the UK?</em></p> <p>I think so, mainly because you can have an enormous panel to soak up the fairly low amount of solar energy for very little cost. I suspect the biggest inhibitor is the push for the combi boiler, adding another water tank as a preheater feeder for the combi is an expense and effort that most folk don't want. I suspect that if most people still had hot water tanks then these things would be more common.</p> <p>Having said that, it looks stupidly expensive to have one installed. £3-5k and realistically you'll still need to use some gas in the winter so the saving quoted are pretty grim, payback in the decades. Whilst the PV pay back is quicker thanks to various subsidies. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213473 Fri, 04 Mar 2016 16:16:19 +0000 Klaxon 213473@http://citycyclingedinburgh.info/bbpress/ <p>While PV is still stuck in the realm of niche off-grid stuff, isn't solar water heating really quite viable even here in the UK? </p> <p>I think that's what the installation at the commie is, there's a little readout of energy harvested at the top of the changing room stairs. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213472 Fri, 04 Mar 2016 16:01:33 +0000 wingpig 213472@http://citycyclingedinburgh.info/bbpress/ <p>The heavy thing need not be so heavy as to require vastly stronger construction. A spinning flywheel is all very well but it still loses energy at a greater rate than a big rock dangling from wire.</p> <p>I assume gigantic Coriolis dynamos were thoroughly discounted as a feasible means of safely harvesting the earth's rotation sometime in the late 1800s? </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213471 Fri, 04 Mar 2016 15:51:25 +0000 cb 213471@http://citycyclingedinburgh.info/bbpress/ <p>Probably make more sense (still not much) for the turbine to spin up a flywheel in the base rather than hoisting heavy things up it. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213470 Fri, 04 Mar 2016 15:22:23 +0000 steveo 213470@http://citycyclingedinburgh.info/bbpress/ <p><em>Incinerating food lacks the valuable exercise aspect offered by hauling a big rock up on a wire.</em></p> <p>Whats that saying, chopping wood heats twice, once in the work and once in the burning. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213468 Fri, 04 Mar 2016 15:17:52 +0000 wingpig 213468@http://citycyclingedinburgh.info/bbpress/ <p>Hmmm. If people are going to go to all the trouble of building wind turbines on huge tall stalks they could start putting big rocks on wires down the middle of them and adapting the blade-turbine mechanisms to be able to switch to winding the big rock up during times when any electrical power generated would be superfluous. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121&page=2#post-213465 Fri, 04 Mar 2016 15:00:31 +0000 wingpig 213465@http://citycyclingedinburgh.info/bbpress/ <p><blockquote><em>"...and probably hideously inefficient. You'd probably be better throwing the pasta straight into a furnace..."</em></blockquote></p> <p>Incinerating food lacks the valuable exercise aspect offered by hauling a big rock up on a wire. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121#post-213464 Fri, 04 Mar 2016 14:58:39 +0000 crowriver 213464@http://citycyclingedinburgh.info/bbpress/ <p>125kW per day per capita according to IWRAT's book. Though that's a (rough) average. If you drive a car, your energy consumption goes up MASSIVELY. Whereas saintly cyclists have even lower energy consumption than pedestrians, it would appear.</p> <p>So the drivists are right: we are smug bar stewards. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121#post-213463 Fri, 04 Mar 2016 14:56:55 +0000 wingpig 213463@http://citycyclingedinburgh.info/bbpress/ <p><blockquote><em>"My fat self at the top of a 23 meter drop has less than 6wh of potential energy yet the power required to get me up a said ramp on the bike is more like 10wh."</em></blockquote></p> <p>Wonder if it would be more efficient to crouch inside a barrel and have someone roll you up? </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121#post-213462 Fri, 04 Mar 2016 14:47:19 +0000 jonty 213462@http://citycyclingedinburgh.info/bbpress/ <p>I think you might be better off burning (or <a href="http://https://en.wikipedia.org/wiki/Anaerobic_digestion">anaerobically digesting)</a> the food you were going to give them! </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121#post-213461 Fri, 04 Mar 2016 14:46:53 +0000 steveo 213461@http://citycyclingedinburgh.info/bbpress/ <p><em>(12½kWh?)</em></p> <p>I read more like 4kwh but even that would be a pretty difficult to generate on bike, and probably hideously inefficient. You'd probably be better throwing the pasta straight into a furnace and using the resulting heat to run a Stirling engine. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121#post-213457 Fri, 04 Mar 2016 14:42:23 +0000 wingpig 213457@http://citycyclingedinburgh.info/bbpress/ <p><blockquote><em>"...any reasonable drop height constraints..."</em></blockquote></p> <p>Definitely not with water, but large rocks are denser than water, though even a well-insulated naturally-lit houseful of keen cyclists who didn't waste any energy output with things like commutes to work/rides outside and who only took cold showers after sitting and generating a few hundred Watts for a couple of hours every day wouldn't make much of a dent in the mean UK daily domestic electricity consumption (12½kWh?) but you might be able to run low-consumption luxury items relatively guiltlessly. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121#post-213456 Fri, 04 Mar 2016 14:38:54 +0000 cb 213456@http://citycyclingedinburgh.info/bbpress/ <p><em>The rock thing</em></p> <p><a href="https://www.gravitricity.com/">https://www.gravitricity.com/</a></p> <p>It doesn't look like they've actually built anything.</p> <p><em>"The key requirement is a deep hole in the ground; it could be a disused mineshaft brought back into use, or it could be a purpose drilled or sunk shaft. Depth requirement is typically 500 to 1,500m"</em></p> <p>Hmm, I suppose I could start excavating under the cellar. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121#post-213455 Fri, 04 Mar 2016 14:33:21 +0000 steveo 213455@http://citycyclingedinburgh.info/bbpress/ <p><em>The rock thing sounds fun but I'm not sure it's practical:</em></p> <p>Its funny I've just done the same maths. Kind of. My fat self at the top of a 23 meter drop has less than 6wh of potential energy yet the power required to get me up a said ramp on the bike is more like 10wh. </p> <p>I'm guessing going much slower up the ramp reducing the air resistance would have brought that right down. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121#post-213454 Fri, 04 Mar 2016 14:30:40 +0000 cb 213454@http://citycyclingedinburgh.info/bbpress/ <p><a href="http://www.scottishenergynews.com/scottish-power-may-double-size-of-cruachan-hydro-power-scheme-if-the-uk-govt-price-is-right/">http://www.scottishenergynews.com/scottish-power-may-double-size-of-cruachan-hydro-power-scheme-if-the-uk-govt-price-is-right/</a></p> <p>The article talks of 400 - 600MW of additional capacity, although I'm not sure if that's the right word to use?</p> <p>An additional turbine hall seems to be a given (so extra power output) but additional dam construction is a "possibility" (but surely a requirement to add capacity?) </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121#post-213453 Fri, 04 Mar 2016 14:24:28 +0000 jonty 213453@http://citycyclingedinburgh.info/bbpress/ <p>The rock thing sounds fun but I'm not sure it's practical: I'm always surprised by how little energy raising water/solids up to great heights actually stores. For example, I might have my sums wrong but I think raising a half-tonne rock up 10m (which is probably the extreme limit of what you could get away with in a residential garden without upsetting the neighbours) would store (up to) 50 kilojoules, whereas the daily energy consumption of a freezer is measured in the megajoules. There's a burning stuff for energy is so popular - coal/oil/gas actually store really quite huge amounts of energy for their size. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121#post-213452 Fri, 04 Mar 2016 14:23:24 +0000 cb 213452@http://citycyclingedinburgh.info/bbpress/ <p>"<em>gravitational potential energy of a large rock on a wire</em>"</p> <p>I'm sure <a href="http://www.atob.org.uk/electric-bikes/electric-bike-hybrid-transmission/attachment/professor-pivot/">Professor Pivot in A to B Magazine</a> discussed such a system (although it may just have been a mini pumped storage system attached to the side of a house). I can't really remember what his conclusions were - probably that it wouldn't be up to much given any reasonable drop height constraints. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121#post-213451 Fri, 04 Mar 2016 14:19:04 +0000 crowriver 213451@http://citycyclingedinburgh.info/bbpress/ <p>Whereas affordable cars and cheap petrol/diesel create journeys that were not otherwise possible too... </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121#post-213447 Fri, 04 Mar 2016 13:51:30 +0000 wingpig 213447@http://citycyclingedinburgh.info/bbpress/ <p>As gravity is always-on it makes some sense to co-opt it into part of a storage battery which can be charged and discharged anytime, but using water as the moveable mass must be quite lossy and it's not ideal for localised use with small energies. One of my things-do-do-when-I-get-my-home-laboratory is build a home energy system based around storage using the gravitational potential energy of a large rock on a wire, mechanically winched up by means of a pedal-driven device (or other exercise machines, so that it also helps the obesity crisis) and able to be discharged either by having the supporting wire drive a mechanical electrical generator (with plenty of gearing and flywheels for a smoothed scalable output) or possibly occasionally acting as the piston in a long vertical chamber to mechanically pump things, though a home system wouldn't have much volume. The available drop could have to be great enough to be able to allow vital systems like freezers to power themselves whilst on holiday when there was no-one to pedal. There could also be a last-resort option to gain height using electrical power, preferably during times of excess from other renewable generation sources. Heat losses from the conversion steps could be captured; they mightn't be much, but could be enough to take the edge off ground-temperature water for hand/dish-washing etc. Ideally the house into which this is fitted would be optimally-built to not require much heating, to be able to use a forced air pressure differential across it to ventilate it and would have things like fridges which create waste heat next to things which need to be heated-up, like hot water tanks. You'd also need much less heating in a house if you needed to spend a couple of hours every day pedalling fairly hard to pull up your big rock on a wire. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=16121#post-213443 Fri, 04 Mar 2016 13:04:19 +0000 neddie 213443@http://citycyclingedinburgh.info/bbpress/ <p>Sorry, but IRWAT's <a href="http://www.inference.eng.cam.ac.uk/sustainable/book/tex/sewtha.pdf">book </a>is just full of techno-bollocks and the propagation of many myths:</p> <p><em>Uranium can be used 60 times more efficiently in fast breeder reactors, which burn up all the uranium – both the 238U and the 235U (in contrast to the once-through reactors, which burn mainly 235U).</em></p> <p>Except that it takes around 30 years for <em>a tiny percentage</em> (not "all") of the 'unburnable' U238 to be converted to 'burnable' Plutonium, which then has to be extracted using an expensive, messy and dangerous process. Fast-breeders are a failed experiment, primarily designed to create Plutonium for nuclear weapons.</p> <p><em>What’s the cost of cleaning up nuclear power sites? The nuclear decommissioning authority has an annual budget of £2 billion for the next 25 years.</em></p> <p>More like £100 billion and counting.</p> <p>And the book fails to take account of many social aspects. E.g. Although plane travel may be more energy efficient than a single occupancy car per passenger, (cheap) plane travel creates new journeys that weren't otherwise possible - like Stag weekends to Barcelona for example.</p> <p>I could go on picking holes in the book, but that would be a whole new book in itself. </p>