Dedicated vs Generic Generation Schemes/Ideas

[Simes123]

Hi All,

New to the forum.  I'm seduced with the idea of renewable energy sources and (finally) am about to move into our own house where I can do what I wish in terms of energy projects.   The drawback (as I see it) with many of the renewable sources - solar thermal, solar voltaic, wind etc, is that they typically generate energy when you don't need it, and don't when you do.  With efficiencies fairly low, and further losses in storage, a generic approach to meeting all your heating, hot water and electricity seems to make them (apparently) unattractive and ineffective, even if they are genuinely reducing energy overall - and the price of entry is typically high.  With that premise, has anyone given much thought to more dedicated and targetted approaches to generation.  By that I mean fixating on the large £££$$$ consuming items and or the enduring consumers? Such that you can achieve complete renewable success at lower entry costs?  ie solve a problem completely rather than partially solving many problems? I think the attractiveness of renewable energy becomes a much easier sell when you can properly solve each problem completely.  Perhaps a few examples:

Free Lighting.  Normally needed only at night, but is an enduring consumer.  With LED lights becoming mainstream, it might be now be feasible to specify a whole house lighting scheme on a low voltage dedicated circuit, fed by solar voltaic, with Lithium-Ion battery storage.  Accumulate during the day, use during the night.   Let's say in a house you had 30x 4W LED bulbs (that you might have bought to save energy anyway).  You are still paying to meet that energy demand.  Assuming you only have 50% of those bulbs on, at any one time, for say, 7 hours each day.  The energy requirement is just 60W/h or 420W a day.   Couldn't this need be met with a dedicated panel and appropriately sized Li-Ion battery resevoir?   For the average consumer, meeting all the lighting requirements for a one off capital charge, might be an attractive proposition.

Free Clothes drying.   A dedicated clothes drying "shed" using Evacuated tubes and solar gain (greenhouse roof!), and a PV cell to operate a fan to remove moisture.   Advantage - you provide an all-weather facility to dry clothes, eliminating the need to tumble dry - a significant energy consumer - without having to try and solve the problem of generating enough power to run a tumble dryer, or relying on ET to heat water hot enough to use for other purposes.

Reduced Kettle Boiling costs.  3kw consumer, for a couple of minutes a time. Rather than try and heat a huge tank of water to meet whole house HW requirements, perhaps focus on heating a small resevoir to pre-heat water that will in any case use a more expensive energy source (ie electric) to reach boiling point.  Ie, use ET to pre-heat a small 4ltr resevoir (that perhaps uses a vacuum flask techology to retain heat) that is used to fill a kettle only.

Gravity generation.  Using the idea of free energy to pump water to a head over a long period, before releasing it to meet short term energy demands for a specific requirement in the house.  I haven't done the maths, so this is probably not feasible, but a low energy Solar Voltaic sourced pump, to move water into a resevoir in the loft (slowly) whenever it can, to release quickly to generate higher power for short periods.  

I'm sure you can think of more - but the premise is to solve a specific problem, rather than try to boil an ocean.  Eating the elephant, one chunk at a time.  I'm sure economies of scale will be the factor (much cheaper per watt to generate 4KW of energy from solar for instance, than to generate a couple of hundred).  But the benefit of the above approach would be to lower the price of entry, and to target the worst (or easiest to solve) problems first.

Any thoughts, or other ideas?

Simon

[dimogga]

Hot water taps - (There's one called the quooker for instance)
Are these more efficient than a kettle? They only do the amount you use.

[Simes123]

Hot water taps - (There's one called the quooker for instance)
Are these more efficient than a kettle? They only do the amount you use.

I think they are more efficient than a kettle - I suppose the question is are they more efficient than the above - I'm imagining that if you can keep the water resevoir small in volume, and you can store any solar gains effectively, then ET might be more effective/efficient overall.  I suppose a combination of ET to warm a small resevoir, and the Quooker idea would be better still.

[SimonHobson]

I don't think there is anything on that list that isn't already possible. I think practicality and convenience are big factors, plus an element of "it's not what we do" and the "WTF" moments when dealing with traditional trades.

So, taking your LED lighting, it's perfectly doable but brings a load of problems - nothing insurmountable, just a new pile of issues to consider. The first is that once you go to a low voltage circuit for the lights, you are then committed to only using (for example) 12V DC lighting - with a corresponding restriction in the fittings available to you (many luminaires using LEDs still expect 240V AC). Volt drops become a serious issue as well - losing 3V at 240V is insignificant, losing 3V at 12V is very significant and not hard to do if you don't use thick cabling.
So on one hand, yes it can be done. On the other, the savings vs running an inverter and a more traditional 240V AC system aren't likely to outweigh the benefits - especially considering all the other stuff you'll probably end up running an inverter for.

On domestic scale pumped storage, I doubt that many will have the scope for doing anything big enough to cover the cost - as you point out, economies of scale mean that a very small pumped storage system will be proportionately much more expensive than a larger system.
Lets look at some figures. Say we can get 10m head (generous unless you have a 3 storey house), and can lift 1000l of water (probably the upper limit without major structural work). The kinetic energy available from that setup would be 98,000J. That's enough to run a kettle for 32s without taking into account any losses - so more realistically probably only 20s or less. To do that, you'd need to shift the water at 50l/s which is a fair old bit of plumbing.
So again, could be done but realistically you'd struggle to justify the cost - and space needed. I think you'd find batteries/inverter would be easier.

The other thing you need to consider is what it would do to your property value. You only need to frequent certain other forums to see that even something as simple as a thermal store is treated as some form of witchcraft - to be removed as quickly as possible. Certainly it's clear that the majority of plumbers are incapable of dealing with them.
With that in mind, if you ever intend selling your house in the future, you need to take into account that many (most) people would see these strange installations and deduct the cost of ripping them out (and installing "standard") from the price they'll pay. For something simple like batteries/inverter it's easy to do - just remove them (and weigh in the batteries at the scrapyard). Replacing a non-standard lighting system could effectively mean a full house rewire, so that's a big chunk off your asking price.

[clockmanFR]

Dark ages again with this water storage, header tanks. expansion overflow tanks, complicated pipe work etc.

Have a look at what the rest of Europe use/do.

[SimonHobson]

Dark ages again with this water storage, header tanks. expansion overflow tanks, complicated pipe work etc.

Err ? Complicated pipe work ?

Have a look at what the rest of Europe use/do.

Care to enlighten us, or respond to what the OP asked ?

[desperate]

Why dark ages Clockman?

both systems have their merits and disadvantages, you know as well as any of us you need to design a system to deliver the goods with the resource available.

I do quite a bit of work fitting accumalators round here to aid the feeble mains pressure that the suppliers see fit to provide. Would be a lot cheaper to boost a cistern fed system.

There is no such thing as THE right system.

Just a thunk

Desp

[Simes123]

Simon,

You make good points about the impact to property value for non-mainstream mods - something to think about.

Agree on the low-voltage losses - I hadn't thought that through sufficiently (and I am an Electronic Systems Engineer!).  Nonetheless, if the proposition was to provide an extensible, yet lower cost of entry whole house Solar energy lighting system, based on LED lights, small invertor, Single panel/battery supported design, I feel that would be quite an attractive proposition.  Much easier to bite off £800 of investment (say) to meet all your lighting needs, than £10k to get a roof full of panels.  Perhaps greater volumes would drive down the panel prices more quickly. I am seduced by the idea of solving a problem entirely

Gravity generation - ok, non-starter - there are more effective energy reserves.

I'd also like to see more progress in non-retro fit solutions.  Why are we still building roofs with tiles, when we could build them entirely with solar thermal panels - I'm convinced it could be cheaper with mass produced panels.   And thermal stores - why are they so expensive, and not standard fit in modern houses? There seems to be a lot of inertia in the building business.

Simon

[clockmanFR]

desperate, your on the ball.
Each water, hot water creation system should be very different to meet the needs. But on normall builds this never happens, ie, as you say your fitting stuff to boost pressure.

SimonHobson, Simes123 questions are brilliant. However moving into his new house he will find that unless he really plans, plans and plans to live in it for the rest of his life, will the work he does be financially viable.

My comments about Europe, and complicated pipe work still stand. Unfortunately there are serious vested interests in the status qua in the UK. So doing the full true Sustainability dwelling is a heck of a challenge.

Simon,  i will not comment further on Hot water systems as i have already had couple of dust ups with the trade folk.  

[desperate]

desperate, your on the ball.
Each water, hot water creation system should be very different to meet the needs. But on normall builds this never happens, ie, as you say your fitting stuff to boost pressure.

These jobs are not newbuilds that have been poorly specced, although that does happen, rather existing installations of combis, electric showers, megaflows etc that have worked ok for years but are now starting to give trouble due to the dwindling dynamic pressure. Probably caused in part because there are now so many mains fed appliances connected. It's bonkers really, loads of folk had the cisterns ripped out over the years, to run at mains pressure and now we reach tipping point they're going to want them all put back in, in the guise of a 1500 quid accumalator, just so they can run off the mainz

Still whaddaya know.............loadsamoney.

Desp

[Simes123]

clockmanFR - the financial viability thing is a factor of course.  I do care about environmental issues, but it does need to be (reasonably) financially viable - I'm not altruistic enough to do it entirely for the benefit of the planet. Nonetheless, perhaps like many, I'm more willing to suck up some upfront capital cost, if I know that I won't ever have to worry about paying for that thing again.  Thus the lights idea - knowing that I'd (ideally) never have to change a bulb, never have to worry about leaving the light on ever, once I'd forgotten about the upfront cost - is very compelling and attractive to me.  Capital costs disappear from the memory relatively quickly, enduring bills are like a sore that never heals

With the state of the market today, my entry point into whole-house Solar PV is too much for me to swallow. If it were less than a £1k for solar lighting, I'd soon forget it.    I might dip my toe in the water with this as my first renewable project.

[dhaslam]

On domestic scale pumped storage, I doubt that many will have the scope for doing anything big enough to cover the cost - as you point out, economies of scale mean that a very small pumped storage system will be proportionately much more expensive than a larger system.
Lets look at some figures. Say we can get 10m head (generous unless you have a 3 storey house), and can lift 1000l of water (probably the upper limit without major structural work). The kinetic energy available from that setup would be 98,000J. That's enough to run a kettle for 32s without taking into account any losses - so more realistically probably only 20s or less. To do that, you'd need to shift the water at 50l/s which is a fair old bit of plumbing.
So again, could be done but realistically you'd struggle to justify the cost - and space needed. I think you'd find batteries/inverter would be easier.

I think that it would be better to  leave the water in place  and use it  to pressurize  air bags under the water.   The pond level would of course change but not as radically as a flow system.  I am constructing a pond at present that will have variable depth using sloping sand covered sides.  It is  intended to  act  as a reservoir for the one beside the house  but it might  be  possible to test the idea for electricity storage on a small scale.   It would need some way of keeping the air bags submerged  and an efficient way to inflate and generate  from them.  Perhaps a Tesla turbine for the  generation part.   

[renewablejohn]

I have designed a renewable energy house using solar and wind but storing it at high temperature using thermal oil (230C) in a standard asphalt container. Obviously some parts are subject to patents so I will sketch over those parts but basically its a whole house solution using high grade heat wherever possible instead of electric.
The heart of the solar system is the concentrated solar panel as used in the Zenith Z20  which has a 38% electric efficiency and 72% overall efficiency. The infra red range of solar collected will be used to heat thermal oil upto 230C and store in an insulated asphalt container. It will be used for cooking as in commercial baking ovens, washing as in commercial laundries  and boiling hot water and steam instead of a kettle. A simple heat exchanger will reduce the temperature for DHW use and by using TEG's electric will be available on demand if not supplied by PV or Wind the waste heat from the TEG providing the UFH.
Wind would be provided by Helium tractor tyre tethered to the ground at 50 mtr height with contra rotating turbine in centre of tractor tyre. Electric generated used immediately or dumped by immersion heater into thermal oil container.

[SimonHobson]

And thermal stores - why are they so expensive, and not standard fit in modern houses?

I think that latter is in part due to the former - who's going to fit over a grands worth of thermal store when they can fit a £100 standard cylinder or a crappy combi ? And from the plumbers POV, he'd rather fit a combi anyway as it's less work for the same money. Of course, it's a bit chicken and egg - thermal stores are expensive because they are low volume and "high tech"* from a limited selection of manufacturers, while standard open vent DHW cylinders are mass produced by every man and his dog.

There seems to be a lot of inertia in the building business.

Indeed. Part of the problem seems to be trades who "have been doing this job for <large number> years, keep your fancy ideas to yourself sonny boy". Plumbers especially seem to be slow to embrace new things, especially things they don't understand - like these "complicated" thermal stores.

* Yes, apparently a cylinder with a coil in it is "high tech" to many plumbers

desperate, your on the ball.
Each water, hot water creation system should be very different to meet the needs. But on normall builds this never happens, ie, as you say your fitting stuff to boost pressure.

On most new builds, there will be little design going into the system. Standard spec for a whole development will be one model of combi boiler (relying on the ever widening output range to avoid doing any design calcs) and a few rads. Plumbers like combis as it makes their life easier, developers love them as it means they can do away with the space taken by the DHW cylinder. Never mind that the airing cupboard is an important part of any house and people still need storage space. I have a house where they've formed a small cupboard above the stairs - and had to put a radiator in it

Still, round my way we don't need to worry about water pressure - we get well over 3 bar all the time. When I bought the flat, the reducing valve was faulty (the valve seat was eroded so it didn't shut off fully) - the pressure seemed to be off the end of the gauge (6 bar) much of the time.

Simon,  i will not comment further on Hot water systems as i have already had couple of dust ups with the trade folk.

You're not alone. There are certain "plumbers" over on the DIY-NOT forum who can be readily baited into a frothed up rage if you question the suitability of a combi for everything. Mention thermal store and some will state with 110% certainty that the only way to deal with it is to rip it out. I wind some of them up by using the term "plumber" as a derogatory term

[Eleanor]

You're not alone. There are certain "plumbers" over on the DIY-NOT forum who can be readily baited into a frothed up rage if you question the suitability of a combi for everything. Mention thermal store and some will state with 110% certainty that the only way to deal with it is to rip it out. I wind some of them up by using the term "plumber" as a derogatory term

Troll like behaviour in any Forum rule book. Life's too short to pick through your capacious posts and work out who you're trying to bait/wind up so be warned