The Trouble with Heat Pumps Part 1

Domestic heat pumps are being heavily promoted by energy companies and the Green lobby as an efficient way to cut carbon emissions while simultaneously reducing  consumer energy bills. 

But do the figures really stack up? In fact is either of the above claim true? Or are the promoted advantages of heat pumps based more on wishful thinking than reality?

There is so much hype going on around Heat Pumps it is difficult to separate the facts from propaganda. But as this topic has been bugging me for some time I thought I would have a go and maybe puncture a few of the propaganda bubbles and economies-of-truth surrounding heat pumps. 

So here goes.

There are two main types of domestic heat pumps. Ground source heat pumps (GSHP) and air source heat pumps.  (ASHP). 

The first two posts will deal with GSHP’s then I’ll cover ASHP’s and in a final post I’ll look at the often stated aim of nationally replacing domestic gas heating with heat pumps. I'll show what I think are some extremely serious financial and electrical issues society will have to deal with if a mass adoption of heat pumps were to be seriously attempted.

Ground Source Heat Pumps. (GSHP)

By any measure, for a normal family installing or updating  their domestic heating with a GSHP, it will be an enormously expensive operation. In addition to the basic installation costs there are also other significant costs that are, if not hidden, quite obfuscated.

The Energy Saving Trust estimated the cost of installing a GSHP in a typical family home at between £14,000 to £19,000. (HERE)

Selectra (HERE) give a slightly higher but more detailed cost break-down

Notice from the above Selectra chart, a bore-hole system (which intuitively feels like the less costly of the two techniques) actually involves over twice the ground work cost of a horizontal system.

So the cheapest GSHP system will involve installing an underground pipe network under your garden. This means your home has to fit the following criteria:  

    • You have a garden (which will be trashed and need relaying)

    • It is accessible for heavy machinery

    • It is on a sufficiently pliable bedrock/soil

    • Your garden is big enough.

With regard to garden size The Ground Source Heat Pump Association (HERE) claim the following:

“As a general guide, for a newly built 3-bedroomed house of around 120 m with a heat loss of around 6kW, two trenches of 30-40 metres in length would typically be required.”

Note “with a heat loss of 6KW”. I assume it equates to the output from the heat pump required to maintain a modern 3 bed house at around 20degC. 

That’s a tiny heating system! Maybe suitable for a new build conforming to all the latest building regulations regarding insulation but hardly likely to be adequate for existing housing stock.

I’d suggest the vast majority of the current UK housing stock would have a lot of difficulty maintaining warmth all year round with a mere 6KW and two forty meter trenches.

EverGreen Energy (HERE) suggest as a rule of thumb you need a garden size of:

"..roughly twice the total floor area of your home from every storey.

The Centre for Alternative Energy (CAT) (HERE) suggests you need 10m of “slinky coil” per KW and that a typical 8KW heat pump requires 400 sqm (20m x 20m). According to the CAT you need 5 meters between the trenches. 

I suspect that both the EverGreen estimate and the CAT estimate assume unrealistically thermally efficient housing. But never mind. We will run with it anyway.

So, how big are typical houses in the UK? Savilles (HERE) tell us what the average floor area per house type is. So using the “twice floor area of your house” rule of thumb we can get a rough idea how big a garden you need for installing a GSHP into each type of house.

Typical Detached House:

• Floor area 152 sqm. 
• GSHP area (twice house floor area) 304 sqm.
• Minimum required garden size: 18m x 18m or 57ft x 57ft

Typical semi-detached house:

• Floor area 93 sqm. 
• GSHP area (twice house floor area) 186 sqm.
• Minimum required garden size: 14m x 14m or 45ft x 45ft

Typical Terraced house:

• Floor area 83 sqm. 
• GSHP area (twice house floor area) 166 sqm.
• Minimum required garden size: 13m x 13m or 42ft x 42ft

What percentage of the UK homes have gardens that big? 

In  fact from (HERE) 1 in 8 UK homes have no garden at all! Of those who have a garden, the median garden size (i.e. the size where half are bigger and half are smaller) is 188 sqm. Which suggests that houses whose garden (if they have one and including front and back) would be big enough is about one third of the total number of UK homes.

Of those with big enough gardens most will be homes owned by the more well-off in society. Especially in London and the South. Notice the NONE of the above fulfil the CAT requirement of 400 sqm for an 8KW heat pump.

If you then assume that only one space (front or back garden) could be practically used for the piping, I would suspect you would eliminate all bar 10% of homes. Of those, almost all will be older and more expensive properties.

So what about bore holes? 

Look at the Selectra table (above) that gives ground work costs. Notice that vertical ground work costs are at least double (with most approaching three times) the cost for horizontal systems. So while there would be less stress on garden area when installing a vertical system, there would be considerably more stress on the bank account. 

Also notice that nasty little reality check paragraph underneath the Selectra table. It details some (not all) of the building work that is excluded from the price estimates.

Water temperature

GSHPs can only efficiently heat water to around 40 degC rather than the typical 65 -70 degC of a gas system.  In just about all domestic scenarios GSHPs are less capable than condensing gas boilers. 

As a result of the low output water temperature you need to install (recommended by most) underfloor heating with your GSHP. Alternatively you could significantly increase the size of all your radiators.

Either way you trash your house. 

To cap it off most companies selling these systems also highly recommend you upgrade your homes thermal insulation as well (assuming that is that there is anything left in the bank account to pay for it)

From installation issues alone I would suggest that GSHP’s are wholly inappropriate for most properties in the UK. There will be exceptions. But they will be exactly that: Exceptions. Not the rule.

Lets not forget, all I have covered at this stage is the impracticality for installing GSHPs in most UK properties. 

I haven’t covered the practicalities in actually running the things yet. (that's in the next post). 

There is also the potential impact on the electricity grid if the proposed scenario of GSHPs and ASHPs replacing gas boilers ever came to pass. ( last post in this series)

The next post (on the problems with the day-to-day running of GSHPs) is HERE

Dorset Renewable Energy Strategy Seeks Endorsement

The Dorset Renewable Strategy Update received a mauling when it was first released for Public scrutiny. Particularly it was lambasted for its doctrinaire enthusiasm for covering Dorset with anything up to 360 huge and ineffective wind turbines. (the so-called "realistic" scenario was for 180)

The DEG (now renamed the Dorset Energy Partnership) have supposedly reworked this document. But really little has changed. Even the errors are still there. (more on that later). This reworked version has been released only to selected groups for "endorsement". I have yet to find any publicity for it anywhere for the general public.

So what about the errors?

I will limit myself to the section that is supposedly explaining Capacity Factors, otherwise this post would go on for ever. Below are the correct figures for UK Capacity Factors, taken from the RESTAT Site Here (Renewable Energy Statistics - Dept Energy and Climate Change - see bottom of linked page titled Load Factors there are a set of excel spreadsheets)

The Dorset Renewable Energy Strategy (DRES) is Here See Section 1.5 page 6

 First we have the 30% Capacity Factor Myth
 [quote]
 "wind power technology has a capacity factor of 0.3, or 30%"
 [quote]

 This is WRONG. At best, making such a statement shows a lack of basic research. At worst it is a deliberate attempt at misinformation.

Notice that from the DECC figures, the average CF for the whole of the UK has NEVER even reached 30% let alone become a typical average. For England it is worse. The 10 year rolling CF is less than 25%. The South West (i.e. including Dorset) it is even lower (23.5%) and has dipped to 17.7% in 2010. This document is supposedly about Dorset - right?.

This is not a matter of just  a "couple of per cent".

A 30% CF generator, over a year, will produce 150% of the energy of a 20% CF generator. So essentially this incorrect DRES statement inflates the energy generation we would expect from a Dorset wind turbine by around to 50%. (from high to low the SW CF is inflated by between 17% and 69%)

Some UK turbines DO make it to 30% - but only about 7% of the English fleet manage it. Even then, none are in the South West.

93% of the English turbine fleet have a CF below 30%.  Actually over 70% fail to even hit 25% nationally.  (See earlier post and prof. Jefferson report link Here).

The South West comes third from bottom of a very dismal English CF league.

 The table 1.5.1 in the DRES then uses the UK national CF average of 27%. At least that is an improvement on the mis-truth directly above it in section 1.5, but this is the UK average NOT the English average,  let alone the (worse) South West figure.

Again the figure is WRONG and grossly inflated - especially when related to Dorset.

As an aside, this table also states the off-shore CF as 35%. This is WRONG. In 2008 (the windiest year in the last 12) offshore NEARLY made it to 35% (34.9%). That is as high as it has ever got. Mostly  it has been around the late 20%'s to early 30%'s. Solar PV CF is given as 10% when it is more like 6 -8% in the UK. Then there is biomass and sewage gas. Laudible as these thermal plants are, they are still thermal plant. Even a  new CCGT plant would have difficulty getting a CF over 80% so, with no references,  the quoted 90% CF looks like a bit of extra and unnecessary guilding.

 2. Then we have "Full Power" myth:
 [quote]
 "a wind turbine will typically be generating electricity for 80% of the time, but will only be generating at full power for a smaller % of time, say 10- 15%."
 [quote]
 These are the power output curves for a Nordex turbine (P graph) and a GE (formerally Enron) 1.5MW turbine.

 A turbine only produces full power when the wind reaches about 12 m/s -  Beaufort Scale Force 6-7. A Force 8 is a full Gale.

 This is a graph of typical UK wind speed distribution over time from Here

Can anyone tell me when and how we manage to  get 10-15% at full power out of this? (i.e. 0.12 at 12m/s?)

Now the Bit that is almost (but not quite) a Myth

[quote]
"producing power for 80% of the time"
[quote]

There is a grain of truth in this - although it is a very small grain and that grain relates mostly to windy areas. It is almost certainly inflated and untrue for less windy areas - like Dorset.

But the real problem with this statement is that it obfuscates the simple and wholly damning fact that wind turbines operate at considerably below their CF for MOST of the time. This is because they only produce significant amounts of power during periods of high wind. MOST of the time they are producing very little (if any) power. This is accentuated in low wind areas - like Dorset.

This section in the DRES on Capacity Factors is  totally dissociated from the true figures you would expect in Dorset. The section grossly inflates the capabilities of Wind turbines that would operate in this area and so promotes potentially incorrect assumptions on the viability and practicality of building turbines in Dorset.

Essentially these figures in the DRES obscure the true worth (or lack of it) of potential Dorset Wind farms.

The DEP analysis of the data appears to extend solely to what they are told by their peers in RenewablesUK.

Any formal Strategy, especially a strategy that could promote a massive level of industrialisation of a rural area MUST be based on accurate figures and MUST remain impartial.  Unfortunately this document fails on both counts.

Yet it is supposedly good enough for "endorsement".

It will be interesting to see whether our councillors allow themselves to get railroaded by this travesty.

The Crime of Economy 7

First of all let me make this clear the concept of the Economy 7 domestic electricity tariff is excellent. It is just the execution that is flawed. (Wikipedia description here)

Economy 7 is a scheme dating from the 70's. Basically the consumers electricity is provided on two separate tariffs. The daily tariff is more than the night-time tariff. The night-time tariff is significantly lower than the median price. This is because during the small hours, electricity demand is low.

At night, electricity  generated from base load generation is often barely required and much generation capacity is wound down to minimum (and inefficient) levels.  During these quiet periods, generators sell their electricity at knock down prices. The theory of Economy 7 is that consumers can cash in on these quiet periods by using cheap electricity at unsocial hours.

Initially the driving force was to provide energy for night storage heaters. They  used the surplus night time electricity to provide heat during the day. Often derided, night storage heaters do not really deserve their dreadful press. True, they do have their limitations. But night storage heaters were the first practical example of domestic energy storage - which has yet to be beaten.

The practical problem with Economy 7 is that it impacts on the huge profits made by the utilities selling it. If the electricity at night is sold at half the day time tariff, even after winding their margins up, the utilities still earn less from each KW/hr than they would from a flat tariff. Utilities don't really care if the night-time energy goes to waste. They also know that most Economy 7 customers have night storage heaters and have no choice but to use Economy 7.

To ensure their (guaranteed) profit stays as high as possible, the utilities charge Economy 7 customers double for day time electricity so the 7 hour night period price can be halved. An Economy 7 customer needs to use at least 40% of their electricity during the night period which is 29% of the day. They need to do this just to break even.

If there was any common sense to this we would all be on Economy 7 tariffs, but at fair differentials not ones dictated by greed.

More of us would use washing machines and other heavy load appliances during the slack periods. This would make better use of our available electrical resources. There would be less waste, and actually less wear and tear on the infrastructure of the grid.

But the massive profits of British Gas, RWE nPower and the others would take a (slight) knock. But no government has yet had the guts to suggest the utilities should behave responsibly.

So don't expect ground-breaking Economy 7 deals any-time soon.

Palm Oil and Wind Turbines

Billothewisp regards chopping down virgin rain forest to grow Palm Oil palms as an act of criminal stupidity. (See Another Green Energy Scam Here)

But he also finds the curious double standards of wind turbine supporters rather puzzling.

Ruining the countryside in Malaysia so we can generate electricity with approximately a 25% smaller CO2 footprint than by using traditional hydrocarbons is, essentially stupid, and is, to be fair, usually opposed by those who are pro-wind.

But really, Palm Oil is no more (or less) stupid than ruining the country side in (say) Dorset so we can generate intermittent and pitifully uneconomic wind energy.

If you consider things like:

-The 200 tons of concrete in the base,
-The mandatory spinning reserve (that is to cover no wind, not breakdown - that's extra),
-Cycling up and down the CCGT backup so the turbines can actually do something once in a while,

The amount of CO2 saved by wind generation is actually less than that saved by stupidly inefficient Palm Oil generation.

The little spat going on between Greeny palmoil advocates and Greeny windpower advocates can at times reach a state of high farce. It is after all, a serious clash of dogma, and bizarre fashion statements. A bit like communism versus fascism but without the manifestos and military parades. Or a clash of religious dogmas, but without the incense and hymns.

Although comedic it is also a tragedy for the poor bloody common folk who have to put up this narrow minded hyprocisy, whether they are in Malaysia or Dorset.

Of course with both of these mad schemes it is likely that after a full audit of the gains and the losses the only profit will be to the land owners and operators.

The unthinking supporters of both schemes ensure that the mountain of gold being drained from the common folk in both Maylasia and Dorset gets ever higher. Meanwhile the countryside (either rainforest or Purbeck farmland) goes to hell.

So in finality here are two picture of different groups of Nimbys, one in Malaysia and one in Dorset.

While they may be culturally different they are both fighting for the same cause - protecting their local heritage and countryside. Both groups are often despised and villified, referred to as Nimbys by those keen to spoil the environment for their own gain, either political or financial. But the Nimby label, whether worn in Malaysia or Dorset should be worn  with pride.

After all, if you don't look after your own back yard, how can you ever help to look after anyone else's?

All Billothewisp can say to both groups is: Good luck, and keep up the good fight.

One day this lunatic obsession with Palm Oil and Wind Turbines will abate.

But it won't be because it is finally realised by their supporters that both schemes are next to hopeless in preventing pollution.

It will be because the next fashionable "cause" will come along and displace them.

Hi Ho Hum