Monday, August 31, 2009

Photovoltaic in Germany

31 Aug '09: We often hear that Germany has something like 200 times the amount of domestic PV installed, compared with the UK. This is mainly down to the feed-in-tariff which is a more powerful incentive than the fixed grant, and incentivises the larger installation, whereas a fixed grant with poor FiT encourages smaller installations.

This photo from southern Germany Aug '09 has a house in the background with?... well I counted 28, but if there is no dormer at the far end, it could be as many as 32 - nearly 6kW! If the sun is strong enough to need to shade the eyes, it's gotta be good for power generation. It demonstrates the benefits of building houses with south-facing 40º roofs! See German Energy Agency.
If you want to know more about the young lady in the photo, she is currently riding a tandem bike from Norwich to Istanbul, which you can read about in her cycling blog.

Sunday, August 30, 2009

Income and Savings on PV

30 Aug '09: This calculation is based on the Solar Century method of calculation. To be truly electricity negative, we need to increase the roof installation from 17 to 22 panels.

Working out the income and savings as a percentage of the cost of installation, that is about 8 percent return on the installation. That sure beats leaving it in the bank at half a percent. And if in the future, electricity prices rise, that shortens the payback with every rise. If electricity is 13p/ kWhr now, any guesses for what it will be in 10 years time?

Costs are based on our present annual consumption of 8500 kwhr/annum.
We have also done a calculation with the idea that the Solar earth charging might reduce the annual electricity consumption by 10%. Optimistic? but this is what we shall find out over the next two years.

Saturday, August 29, 2009

Solar Earth Charging Elsewhere!

29 Aug 09: I discovered that Solar Earth Charging has been tried on a commercial building by Renewable Energy Systems at their Beaufort Court HQ, near Watford, UK.

They are using an underground conical tank of 1400cu-m of water, heated by a large array of solar thermal panels. The 20m diameter pool is level at the ground level, but topped with 1/2m of polystyrene, but not insulated underneath. 50% of the heat brought in from the panels stays in the water, and the remainder is an earth charging process, soaking into the surrounding soil for later reclamation. They claim it's a world first, for which I am thankful, because it supports my case for doing it on our house, which may be the first for a Domestic property.

I have also been told by my Wikipedia friend, Engineer Mike SM about an article describing an office conversion project reported in the IEEE journal Sept 2007 in San Jose California (also claiming to be a world first). The architect is David Kaneda. The building is using reverse cycle heat pump, so that in summer, the pump is cooling the building and dumping the heat underground, and in winter, it is getting the heat back from the same place. They are also generating 30kw of rooftop PV, which is easy in the sunshine of San Jose.

Pump up the Panels! - all the twos, 22!

29 Aug '09: For the Photovoltaic - we have a currently have a proposal for 17 PV panels, to give us a rating of 3.06 kw. The unit costs such as the meters, scaffolding, regulators etc are the same if we have 10, 15, or 20, and the maximum we are allowed to aim for is 4kw. So while we have the chance, we should maximise by aiming for 4kw!

So we have asked EvoEnergy to increase the installation to 22 PV panels, to give us 3.96 kw, the highest we can go before being counted in a different Feed in Tariff bracket. That would generate 2940 kwhr/annum on our ESE facing 40º roof - Generating income + savings of £1336. This is a 25 year contract of guaranteed income, as long as the system is maintained and working.

This means that on summer days, we would generate the entire day's requirements for the house before we have breakfast, the rest is profit. Only 15 mins is enough to power our washing machine for an hour. One hour of good light powers our supersize fridge for 24 hours of continuous running.

We shall have access to the panels from our rooflights, and will have a display in the kitchen to show the statistics of generation.

We will get a meter fixed to the Ice Energy Heatpump, so we can see what that is using day by day. Unfortunately, I haven't recorded precise consumption week by week for the last 2.5 yrs, but I have all our quarterly bills and know precisely the annual consumption, so if our total consumption is reduced by the Solar Earth Charging, we know it has worked.

For the initial installation cost, it only took about 10mins on line, entering details of our project, to get approval for a grant of £2500 from the Low Carbon Trust, subject to us completing it and submitting proof. They also require confirmation that all the other obvious good things have been done, such as insulating the loft, and fitting low energy lightbulbs.

Friday, August 28, 2009

Researcher on board!

29 Aug '09: I have been talking to Dr Chris Wood of our own Department of the Built Environment (Uni of Nottm), who has recently graduated as a Roger Bullivant supported PhD student and whose work was on Ground source heat pumps from piles under residential buildings. The next stage in his research is likely to move in the direction of commercial buildings with deeper piles, and then of Solar Earth Charging. He has been extremely helpful in my project, and likely to take a close interest. Also he has already worked closely in conjunction with my own supplier of heat pumps, Ice Energy.
    He has raised the question of whether we should continue to work with a low temperature solar collector or go for the pro quality high temperature solar panel. This question will be one of the discoveries we make from the project. I favour the humble collector, partially because it is so cheap that every heat pump owner could afford to include it in their system if they are making the investment in boreholes.
    He also pointed out that there have been presentations and essays on the topic of Solar earth charging (including ones by himself), but nobody has yet agreed on what it should be called, and that these have been kept as industrial secrets and not published on the Internet. So here goes. How about Solar earth charging?

End of Oil.... end of Society

28 Aug '09: I have been reading the website by Richard Duncan, and it is very thought provoking.
Richard Duncan's Olduvai theory is about the link between Energy Population and Society which states that the era of high energy consumption is 1930-2030. After that, there is not enough oil for what we regard as normal life, and beyond we face unimaginable difficulties and changes, and breakdown.
The human conflict that follows that End of Oil will be just as much a problem as Climate Change, and many of the wars in the last 50 years have been linked to the control of resources, even if they seem on the surface to be linked to territory or religion.
     Skeptics say that we can gradually adapt to CC by migration, retreat from the coast, air conditioning, technology developments etc... But the flaw in this argument is that most of the adaptation process requires vast energy consumption - which will accelerate climate change even further.

But end of oil will occur much more suddenly when peak oil suddenly drops off after 2020 and yet the population of the world has risen yet further. The graph of oil is like a steep cliff after 2020. Oil is essential to manufacturing particularly of computer and home products, and there will be a time when it is too valuable to burn in cars so has to be rationed. The energy from Oil is essential to the delivery of Food, and delivery of Water. The suddenness of this will cause mass unemployment and wars.

As electricity is also essential to the stability of our society, it makes mass Microgeneration a very important capability, if only more people would do it. It also requires Rainwater catchment and Food cultivation on a massive scale by having it in millions of homes.

I know someone in Texas, whose plight is typical for many americans living in low density cities. His car is unreliable, his journey to work is an hour each way, he can't get to work on time, so his boss makes him unemployed. The city is so vast and low density that there is no work near the home, and no transport to where there is work. Period (as they say in the US). The country is in trouble enough now, but in bigger trouble when oil disappears... or there will be more wars to grab the remaining reserves.

Richard Duncan's Olduvai theory is about the link between Energy Population and Society which states that the era of high energy consumption is 1930-2030. After that, there is not enough oil for what we regard as normal life, and beyond we face unimaginable difficulties and changes, and breakdown.

Thursday, August 27, 2009

Reading the deep earth temperature...

27 Aug '09: Ice Energy have taught me how to read the actual temperature of the deep soil. Basically, we do this by setting the GSHP control so that it is pumping the glycol round the circuit without the compressor running, long enough until it gets to a steady state of the temperature deep down, then read the temperature of the glycol circuit. This requires about 15 mins, to be sure.

I tried it today, and after 5mins running it said it was 12.8 and after 10mins circulating, it said 13.1. This surprises me.
I tried it again a day later, letting the pump run for 15 minutes cold circulating, hours after it had last done any heating (so no heat in compressor) and it levelled out at 12.8. This gives a good indication of summer temperature.
   The last 5-7m or so in each direction is running from the house to the borehole through the ground near the surface, which is seasonally warmer (and conversely colder in winter), so maybe that affects it. I was expecting it to be colder. I shall take weekly readings so see how this develops. I am already taking daily readings on the electricity consumption. Ice energy have offered to supply a meter specifically for the HeatPump, and I have bought an Owl meter to make it easier to monitor the overall house.

Solar Electric Panels ahoy!

27 Aug '09: We have accepted a quotation from EvoEnergy for 17 Photovoltaic panels to go on the roof as the first stage in this project. This is a separate wiring/plumbing operation from the Solar geocharging, so the PV installation can go ahead in September. The installation is calculated to be 3.06 KW optimally, equivalent over an average year on a roof of our pitch and orientation to be generating 2270 kWhr/year.

On the new feed in tariffs of next April of 36.5p p/kWhr for retrofit PV, this is equivalent to earning and savings of £1032 a year. We presently burn a precise total of 8500 kWhr per annum. That means we would still be needing to buy power from the grid, costing us £1100 /annum. So from the start of April, we would nearly be electricity neutral, ie earning the same as we spend. If Solar earth charging cuts that amount by only 10%, that will make us electricity negative, i.e. minus quantity electricity bills.

The grid electricity we get is from Good Energy, which is 100% renewables. Even before April 2010, Good Energy have a scheme to offer preferential tariff of 15p/kWhr before April 2010.

All this does not make the house carbon zero in the true sense, but it does if you allow in the mathematics of tariffs and offset.

We have had approval for a grant from the Low Carbon Buildings programme. For anybody reading this, please note that we are in a very beneficial timeframe. If you have PV installed now you qualify for a grant that is not likely to be available when the new Feed in Tariff starts in April 2010.

Because I have ArchiCAD Summer School and the start of University term coming up fast, we are delaying the installation till 28th September, and it should take 2 days.

Tuesday, August 25, 2009

"Seasonal thermal store"

25 Aug '09: Having thought this was a solo idea, I am pleased to find that there is a discussion of this already, and one example can be seen in the expression Seasonal Thermal Store. My respect for Wikipedia has grown enormously now I have seen how carefully the moderators and readers weigh up the validity of material submitted for Wikipedia.
    An engineer has written to me the following: "I am aware of at least one office building that was constructed in San Jose, California, USA that I believe uses the technology discussed in this article. More notable references like this (from independent sources) would improve this article. This office building is famous because it has zero energy footprint and a zero carbon emission footprint. I can't find the reference on the office building right now. It was published in the IEEE Spectrum Magazine in the last year or two."
     So with Mike's help, I will either strengthen the article, or I may reflect on it and allow it to be deleted on the basis that Seasonal Thermal Store seems to sum it up with more academic strength than I could give it. My contribution is that I am actually doing it. But not just doing it... getting it monitored by dataloggers, with support from a PhD student from the University of Nottingham.

Monday, August 24, 2009

New Wikipedia Entry

There is nothing in Google or Wikipedia about this, so I have now created an entry for Solar Earth Charging .
Unfortunately, Wikipedia keep threatening to delete it. If one provides too much information they say it constitutes advertising, and if I provide too little, they say that more information is required to back it up.
'Solar charging' does already appear in google referring to plugging electric cars into solar powered charges. 'Solar earth charging' more correctly describes the activity of Charging the Earth.
If they do delete it, I shall just have to be patient and restore the entry in a year's time, when Wikipedia accept that such a thing can exist, once it has been running for a year and there have been some articles about it.

Is this idea really new?

I don't think the IDEA of Solar Charging is new, but it doesn't seem to have been done on a full size house with deep boreholes, and subjected to testing and proof of concept. The Ice Energy manual has a circuit diagram showing how to link the Heatpump to fan coil units for comfort cooling in the summer (whereby cold glycol is circulated and surplus heat is dumped underground). Similarly, there are proposals for making use of a VBX unit (for air based heat reclaim). These require a circulating pump isolating valves and insulated pipes up to the collector. We also need to have the expansion tank moved up to the highest point.

The difference here is that instead of 'accidental gains' being sent deep into the ground, the plan is to hang a collector externally (with no specific purpose such as water heating).... it will be solely to harvest as much solar heat as possible, and send it straight down deliberately ... with no certainty that it will come back.... but a curiosity to see if it does.... and a determination to quantify the result.

Sponsorship idea

We are considering an offer of industrial sponsorship. But it worries us that if the project is bound by conditions to be confidential, it would mean the end of this blog, and prevent me being able to write articles promoting this idea (we think it's a good idea and want others to know about it.) The simplicity of the components, and the fact that the expensive bits - the GSHP and the boreholes are already in place - mean that sponsorship is not really necessary, but advice is!
Any company sponsoring this would obtain a market leadership if the idea has commercial potential, by being privy to source data, but first to provide the product that meets what is undeniably a 'good idea'. The company who has proof of concept, plus precedent and recommendation, and a viably priced product will be successful.
So... keep watching for news on this.

Friday, August 21, 2009

Idea for an Access Deck

I dont like Ladders! who does? Even if it only having to walk under them.... But if there is a need for occasional access or inspection, a wall mounted panel, even at bedroom window height may require occasional access. We might even want to add another panel at a future time. So I think its worth the cost of a shallow (60 cm) access deck of steel tube and expamet, just under the panels so that someone can get out there for inspection or maintenance. A bit like the shallow walkway on a double skin facade.

Wednesday, August 19, 2009

Do it with DC pump?

One thing that made me happy about using flat plate Solar Panels was that the pump would work when the sun is shining, so there would always be PV power to meet the demand of the pump.

Conversely, one thing that made me unhappy about using the plastic radiator to make smaller but continuous gains, even at night time or during rainy days was that a pump would be working longer hours.

Talked again to David at Ice Energy, and:
1. He comes up with the possibility that it needs only a 40watt pump (I was worried that it would be in the region of 200watt).
2. We can tweak the 'delta-T' to trigger the pump, so that it isnt running all night, unless temperature is favourable - becomes mostly a daytime device.
3. We can have a small PV panel on the south facade next to the plastic radiator, that is charging up a DC battery (car or motorcycle) and have a DC pump. So it is definitely able to work in daytime, and works some hours into the evening, while temperatures are still warm, and never requires power from the grid.

Do it with black plastic pipes?

19 Aug '09: I had a wonderfully advancing conversation with David Atkin of Ice Energy, which has also reduced the cost enormously and is likely to increase the efficiency of the installation.
      We want this to be a research project, and an exemplar for future house design, so affordability is part of the requirement. Solar charging is worth doing in his opinion, because deep down, the earth does get colder. A heatpump working for 25 yrs will gradually lower the ground temperature until it reaches a new equilibrium - the precise time depends on the soil and the depth of hole, size of house, so 25 yrs is an estimate. So, Solar Earth Charging is going to prevent that temperature decline.
     Pro-quality Solar panels are heavily insulated with a glass top, so only collect heat when the sun shines. They are aiming for a high Delta-T in order to make hot water, but we are not doing that - we don't need glycol at 60-80º. The solar panels do nothing if the sun is not shining - which can be several days in a row in British summers.
     On the other hand, If we have an array of uninsulated black plastic pipes in the open air (like a swimming pool heater) this will pick up ambient air temperature, so it will be able to charge the ground with low grade heat throughout summer nights, long rainy days etc., so long as the air temperature is hotter than the below ground temperature - more than eight months of the year, day and night. Whenever the sun shines, it will of course harvest even more heat. The black surface of the pipes will reduce UV degradation.
     As 4 sqm of pipes costs less than £ 200, it can be replaced after 10yrs if need be, and not even require scaffolding. This can be mounted on the South wall, not on the roof, so that is it getting more solar heat in Equinox and Winter, but benefitting from air temperature as the wall heats up in summer sun. There is a zone of very hot air over the surface of the wall when the sun is shining. For summer hot water heating, the heatpump will benefit directly from this higher temperature panel.
      The idea that an industry standard Solar panel would actually reduce the efficiency of our idea shook me, but in a most beneficial way. Getting heat on rainy summer days and balmy nights from the ambient air temperature is an enhancing idea.
    The compact collector can be fixed to the South wall right next to my bedroom window (for easy inspection). There is a small tree opposite which does not shade the wall yet, but we will keep its height trimmed. There is a direct route from there to run the insulated connecting pipes through the loft to the position above the heatpump and the storage cupboard where we would want the displays, datalogger, pump etc located.
      It simplifies things because the PV installation by EvoEnergy has more roof area to work with and it totally self contained as a package of work, and need have no connection with the Solar Charging project.
     The Solar Charging project - compact collector on the South wall and the connection to glycol loop - would become a totally Ice Energy-DNC-University of Nott'm project.

Orientation and Access

As you can see from the Googlemaps photo (taken about 4.30pm sometime in 2007), there is North-South ridge, but there is a clear 10º bias towards the south if we use the East roof.

So the West roof has a 20º disadvantage. But it is illuminated in the afternoons, when the air temperature is hotter, and the skies less hazy, although afternoons tend to be cloudier.
Access is governed by the Velux Rooflights which only face east. PV panels work better in cold air conditions, so the East face is better, because we know the roof on the west gets infernally hot in the afternoons.

It is tidier for maintenance and installation to have all on the East. We would not want to have anything above the glass conservatory incase of a dropped spanner by someone doing maintenance.

Following some of the decisions on the use of Plastic pipes instead of Solar panels (described above), we are likely to mount those on the south wall (despite the nearby tree) and maximise the PV on the East Roof.

Decisions, decisions!

Tuesday, August 18, 2009

Is there a Plan B?

Well this is Plan B!!

Plan A is to have both Solar Earth-Charging with solar panels, and Solar Thermal Water Preheating with a storage tank and one solar panel. However, apart from the additional cost of the panels and the extra tank, we would affect the performance of the Heat Pump (favourably), but making it difficult to assess the sole contribution of the Solar Charging. As 75% of the workload is Space Heating, we know that this is the component that most needs solving.

Plan B is to have solar panels linked directly to the ground loop, charging up the deep boreholes throughout the year. Relatively cheap, amazingly simple, but not been done on a domestic property yet! - and we not do Hot water as this would confuse the data collection process.

Plan C requires that we do Plan B first. If it works, we are all happy, and the extra Coefficient of Performance is assessed, and then we could consider whether it is necessary or beneficial to add an extra panel for a Solar Preheating tank. This could be on the west roof, with a Velux added for maintenance access.

Plan D requires us to do Plan B first. If after two years, the experiment was ineffective, and cannot be made better (eg by an extra panel), then we stop off the glycol collector loop and simply instal a water preheating tank in the loft using solar thermal panels on the west roof - which we already know will produce benefits.

Encouraging thoughts...

As a counterbalance to the sobering thoughts, I have had a huge degree of encouragement from Professor Riffat, President of the World Society of Sustainable Energy Technologies (WSSET) who considers it to be a very worthwhile idea.
It is one that his associates have thought of, and tried to model theoretically... but not yet built a full size realtime prototype. In fact he may have a PhD student working on it now.
To test it fully, it takes land, it requires real boreholes and heatpump, it requires a full size house with a real family in it using the heat, the right kind of soil... that is difficult to find for researchers... so I am prepared to provide that.
Some of their tests have assumed 10m depth, but the upper 5m are ineffective as they are affected by seasonal differences. But with our boreholes we have more than 40m down below the 5m layer that are unaffected by winter or summer.
We discussed the risk that we might get zero percent efficiency. ie. the temperature of the lower soil would stay resolutely at 12ºC. Well even this would be a benefit! Without the Solar charging, we know that the temperature of the deep soil would fall and the Coefficient of Performance (C.o.P) of the Heatpump falls too. So if our charging did no more than maintain the temperature at 12º that would enable the Heat Pump to work at its expected efficiency (C.o.P) of 4 - which is a benefit. If the idea works and the deep soil rises significantly, then the GSHP would simply work with great efficiency - saving electricity in the process.
He proposes to help us with flowmeters, temperature displays, dataloggers etc and the help of a PhD student.
This is really the only point of doing this - the payback may go beyond my lifetime, but if this is a world first, and it works, then it's a wonderful piece of research that could be copied by thousands of householders.

Sobering Thoughts....

I had a chat with two of my colleagues at the University. The first (DE) seems wholly sceptical about the idea... unless I am prepared to accept a lot of inefficiency - insofar as that can be defined and measured - difficult when the active area is 50m deep, and has no real limit horizontally.
If the cylinders of clay were in a vast barrel of polystyrene it would be a splendid idea!
If 90% of the heat put down is lost, is the 10% retrieved worth it? Or is that figure 50% or 95%?
He feels that the summer heat will move too far away to be willing to return in winter.
Objects with high thermal mass work very well diurnally, eg daytime heat recovered in the same evening, as in thick adobe brick walls in middle east. So solar heat gains on sunny winter days might come back the very same evening.
The question is.... would heat stay around long enough to get the summer heat back 3-4 months later?

My other colleague (AH) is prepared to do some calculations for me (although is due to depart on holiday for next few weeks). He pointed out that conventional solar thermal heating was not as efficient as the sales people claim - because if hot water is not being used a lot, the tank and the panel reach stasis, that is, no more heat is sent to the tank because the 'delta-T' (temperature difference) is inadequate and the panel sits there doing nothing even on sunny days. Then you draw off hot water on a cold rainy day, and there is no more until the next sun.
He agreed that with one aspect of my idea, that the glycol going down to the ground (even if as hot as 40degrees) would come back cooled to something like 12 degrees, so that there would always be a workable Delta-T, and the panel would work at full efficiency even if sunshine was intermittent. And the hot water would always be hot because the Heat pump efficiency would be improved., and 50m down, the ground doesn't know if its summer or winter above.

Monday, August 17, 2009

Could this apply to a Newbuild house?

Most people building a New House prefer to go for the 'Slinkies' laid in a trench, or a 'radiator', because it is so much cheaper to instal.

For those with shallow trenches, it can be cost free. I know someone who has enough land for the slinkies, bought a second hand JCB on EBay, dug his own trenches to lay the slinkies, filled them back in, and resale value of the JCB on EBay is still worth what he paid for it.

Radiators (aka Compact Collectors) are a mesh of plastic pipes that are usually hung vertically in a deep narrow trench, or laid flat in a wide trench. Both of these are getting warmth from the current season's solar gain, and also the rainwater that falls on the ground they are in,. The ground temperature fluctuates seasonally, but there is enough mass to get through the winter. The required number of collectors is dependent on the predicted heating load of the house.

If you have enough land, you would NOT plant boreholes as they are fearfully expensive and require a professional drilling crew. But their benefit is that they get heat from Deep Down.
In our case we had to have boreholes, as the garden is too small for 'slinkies' and too narrow for a deep trench with a 'radiator' array of pipes - it would undermine the house foundations, and the neighbour's hedge.

So £5,000 poorer, we do at least have the best solution, because the soil 48metres down is dense and undisturbed and there's a lot of it. The boreholes will last hundreds of years, rugged pipes set into Bentonite. You could replace the heatpump, or even rebuild the house a few times, using the same holes!

The 'cylinders' of clay reach down 48m deep into the earth, and there is nowhere else for the heat we dump into it to go to than to stay there. And much of it will be returned when we withdraw the heat in the winter. It is like charging a battery. Even in Winter, there are sunny days and the solar panels will work. In our case, the 'store' is uninsulated, the distance sideways extends to near infinity.

Here's an idea for New Builders: The solar charging pipes could be laid flat (horizontally) in an insulated stack of bricks (second hand or waste) or GGBS concrete, Blocks of Paraffin wax, or even quantities of re-used or contaminated soil, all set in a very big 'box' of polystyrene foam. If you dig the hole for the 'box' you could refill with the earth you took out. Then you can run a radiator of Solar Charging pipes through this 'store' - the same pipe putting heat in as taking it out. And Build the House above!

But how big do you make this store for a whole season? One metre deep? Two metres? Four metres? Perhaps insulate the top and sides, but not the bottom, so that it extends vertically downwards to no limit, but does not lose heat upwards or outwards. This could be an expensive question to answer by trial and error, although it could be computer simulated.

• Cheapest and most sustainable solution would be to re-use the earth you took out to dig the box - earth neutral, and just requires a digger. You can even bury other people's soil if they have a surplus.
• Most thermally effective solution would be a large quantity of blocks of paraffin wax - they remain the same temperature, but go on absorbing heat, and then releasing it almost for ever - a Phase Change Material.

Do we still need a Solar water preheater?

We are still wondering if it is worth having the solar water preheat tank at all now.
The GSHP will work so much more efficiently when the clay in the deep borehole is warmer that the cost of a separate solar thermal water preheater may not be justified.
DHW overall is only about 25% of the workload of the GSHP over the last 2.5 years. And it has only been 13% of the workload of the Immersion heater function in the heatpump.
It would completely confuse the data, because the obvious benefit it would give to the efficiency of the heatpump would make it difficult to decide how much efficiency had been added by Solar earth charging.

Really, why do we need to do this?

17 Aug 2009: The IVT C6 ground source heatpump is correctly sized for the house, and the twin 50m deep holes are sufficient for a house of this volume.
The problem is more to do with high thermal capacity of the house and the use of underfloor heating. When the house needs to raise a few degrees, the heatpump is dismayed at how long it takes to warm up because underfloor heating cannot get too hot without the tiles cracking. So the GSHP goes into overdrive, using the Immersion heater to speed up the process.
   In winter, the GSHP should really be left on all the time, so that the house never has a chance to cool down. The target house temperature is usually 21 degrees C, perfect by day, but a little too hot at night.
   If I can have a criticism of the machine, it's a pity that there isn't a fingertip control to change the GSHP to Night mode, ie allow it to work to a night-time target temperature of 18, and then a quick fingertip control back to Day mode.
By having much warmer ground to get the heat from, the GSHP will more rapidly find the heat it needs. However we will still have to remember that the house takes time to warm up if it was allowed to cool down (e.g during a holiday period).

During the Summer period our normal consumption is 9-11 Kwhr per day. Over the last 30 months, our Average daily consumption has been 23 Kwhr. Clearly we are using too much in Winter, and Space heating is the primary difference between the seasons.
  Other things like Lighting, hot water, laptops, printer, Fridge, power tools, dishwasher, washing machine, oven and hob use are much the same .
(Winter Lighting is slightly heavier for slightly longer hours of dark, balanced by more lawnmowing in Summer).
[Postscript: There is a night mode, I just didn't know about it at the time. Knowledge like that has to be eked out of Ice Energy a bit like someone sucking marbles out of a jar with a straw.... one item at a time!]

How did the Boreholes get there?

We already have two boreholes under the house, which were put in November 2006, for the Heatpump. They are under the driveway.
     One goes down 46.5 m and the other is 48m down. They join at the surface. The soil is dense marl ie a mixture of clay and limestone fragments all the way down. Assuming a 3.6m active radius around them, and 5 m between them, that equates to about 8,000 tons of dense marl to dump heat into.
     The two boreholes contain a rugged plastic U-tube, that is contained in a sleeve of Bentonite, non-setting clay. The pipes meet at a manifold in an inspection chamber in the drive.
     The solar panel connection to this loop can be made in our Utility room, just above the heatpump.
     The boreholes are going to last longer than the house, theoretically you can connect a new technology GSHP every 25 yrs, or even build a replacement house every 150 yrs, and the same borehole pipes will suffice - assuming that the volume of the house is comparable, or that future house are even better insulated.
Youtube movie about the HeatPump, March 2007 for Radio Nottingham
Youtube movie about the Drilling Nov 2006 and more related to that.

Flat Plate Solar Panels

I wondered about which sort of solar thermal panels to use. Flat Plate or Vacuum tubes. The panels are not facing due south. They dont have to be super efficient, as their job is simply to dump enormous amounts of free heat into the deep clay.
These flat plate panels in the photo are used by my Sister in Law on the hillside behind her house, facing due south. They do a splendid job of providing all their hot water through the summer.
Another thing that has bothered me... the roof ridge is North-South, meaning that we dont have any ideal roof angles. The south facing Garage roof is too small and is over shaded. So if we wanted ideal solar capture, we should have one on the west and one on the east face, so that capture takes place through the sunny day. However, this complicates the plumbing and I am somewhat anxious to keep all the 'gubbins' on one side (the East), for easy maintenance.
I am told that Flat plate work better on an East or West facing roof than Vacuum... lets hope so. Two things, they are cheaper than an array of Vacuum tubes and less prone to wind damage.

Is this the First time ever?

It is difficult to know what keywords to type into Google to find out if anybody has tried Solar Charging. Perhaps I need to create a new Wikipedia page for it!
The R&D specialist of our Heat Pump supplier Ice Energy, say they have tried a small rig to put heat into the ground, but as a test. We are told we would be the first member of the public that they know of to try this.
We would be grateful for reports of any similar experiments or installations.

What about Electricity?

The original idea was to save Electricity.

The GS heatpump uses more electricity than we expected. The Immersion Heater function comes on all too readily if it is not getting enough heat from the ground, and not quickly enough.

The solar earth charging would save more energy than an entire roof could generate with PV. But how about the idea of doing both!?

We used 8500 Kwhr from Aug 08 to Aug 09, and we would like to reduce that. The UK govt. have announced german style Feed-In-tariffs starting next April 2010 which make PhotoVoltaic well worth doing.

Before April, 2010 the grants system is still in place, but after that, we will get 36.5p/hr, 3 times the amount paid for Grid electricity. This is in effect somewhat more because we can use home created electricity direct and dont have to pay the Grid supplier for it. This equation is explained on Solar Century's website.

Therefore, we will also provide Solar Photo voltaic Panels (which will of course power the pump that is moving the glycol down to the soil), but is likely to generate more than 2000 Kwhr per annum for this angle of roof in this location.

The income from the panels could be more than our total annual electricity bill - meaning that we have a negative electricity bill!
For the PV, we are currently working with EvoEnergy, a local agent for Solar Century.

How is this funded?

Although I am paying for the panels, scaffolding etc, (and there is no grant for this idea of "Charging the Earth") it's pioneering work and we will work hard to write up the results and promote the idea.

I will get a PhD or masters student to record results, and ask the school about data-logging, extra flowmeters etc.

Ice Energy, the Heatpump company will provide 'virtual sponsorship' ie as much advice and support as I need, and draw all the circuit diagrams for us and perhaps cover sundries like thermostats, flowmeters etc necessary for proving that the idea works, providing I deliver all this information. They can see the huge potential.

Can anyone Charge the Earth?

17 Aug '09 : This is not the universal answer! Beware... The idea only works if:

1. You are using deep boreholes, where the heat you put down doesn't just escape to the air or the water table, as it would do with 'slinkies' under the lawn.

2. The soil round the borehole must be waterproof, ie it is clay or rock. Gravel with ground water will not work as heat will be taken away by water.

3. The primary part of the investment already needs to be made to put in the heatpump, the circuitry and boreholes and glycol filled pipes, So to charge it with heat, all one needs is to tee on a loop of glycol through the solar panels with its own thermostatically managed pump pump. This works in summer even when the heat pump is turned off or sleeping.

However... there are other things you can charge: a large storage tank, a shallowly planted grid of pipes in soil underneath the building - the main idea is to put it where you can get it back later.

Here's my Facebook entry for 16 August 2009 - committed myself publicly to doing this project!

What are we planning to do?

We are planning to have 4sqm of Solar Thermal panels to deliver heat deep into the ground - Charging the Earth!

1. Our original idea had been just to top up the hotwater by preheating it before it went to the Heatpump (GSHP). Delivering water at 40degs instead of the 10-12 that the mains supply comes up from the ground at. This would reduce the running cost of the heatpump.

2. We then found that the proportion of workload of the heatpump is 27% HW and 73% space heating. So saving only on hot water will not save as much as intended. We also found (from the log on the GSHP) that although it had used the immersion heater function for 440 hours since commissioning, only 13% of this had been on DHW, and the 87% balance on house heating. So.... house heating is the problem that most needs solving.

3. The idea migrated to one or two tanks in the loft, one that would be for preheating water for the domestic HW system, and the other one for space heating. This would be easier to get data from, but way too expensive for householders to copy our example, and difficult to get all this in the loft. So we reduced it to the idea of ONE large tank, big enough to store heat and for the ground loop to borrow heat from that, and for some incidental gains to be transferred do the 48m deep boreholes. The loft is big enough to take any weight and size of tank as long as it fits through the loft hatch.

4. The benefit would only happen in equinox and winter when the pump is pushing glycol round, so is very hit and miss. In summer, the tank would get very hot, and the heat pump would not transfer heat down to the ground.

5. After talking to the Heatpump supplier, Ice Energy, we realised through discussion, that the glycol could be routed directly to the Solar Thermal panels, using a simple thermostatically activated diverter valve and pump that would work even when the pump is turned off or hibernating - during the summer months.

6. This means that throughout the summer, every small amount of energy is stored underground, for our heat pump to retrieve in the winter. The ground below, approx 8,000 tons of dense clay, could absorb a delivery of heat during the summer, diffusing out to the clay around the boreholes.

If it works, but needs more panels, we can add a extra. If it doesnt work, then? ... well, we know it will work to some extent, even if its only benefit is to maintain stability in the ground temperature and thus ensure the optimum coefficient of performance of the Heatpump.

Popular Posts