Which Home heating method – Electric Heat pump or low emission Wood Burner?
Posted 12 Jan '10 03:35 AM
Ambient air concentrations of both PM10 and NOX in the Auckland region, currently exceed accepted health guidelines and standards.
PM10 particulates kill about 600 NZ’s per year from respiratory disease and cancer.
The largest single contributors to annual emissions of PM10, are motor vehicles (41%) but surprisingly, domestic heating (38%) is right up there competing with diesel transport – the (21%) balance comes primarily from industry.
A Heat Pump produces no PM10 particulates but produces plenty of CO2 via electricity generation.
A or low emission Wood Burner produces little CO2 but plenty of PM10 particulates.
LOW EMMISSION WOOD BURNERS:
‘Existing models’ of wood burners have an average PM10 emission rate of 12 g/kg.
These are real killers, and will gradually be replaced with more efficient cleaner alternatives.
‘Current models’ of wood burners have an average PM10 emission rate of 4.6 g/kg.
If for our home heating, we substituted ‘current model’ wood burners at a rate of 25% and had a proportional reduction in electricity usage, the annual health cost to NZ would be $67 million from PM10 emissions.
‘Low emissions’ wood burners could achieve an average of 1.0 g/k or 1/12th the PM10 emission rate of ‘existing models’ but this figure is currently unrealistic as this efficiency is rarely achieved in practice. I will use it only as a future inspirational standard.
If 25% of electricity users and 25% of gas users switched to low-emissions wood burners the annual health cost would reduce to $15 million from PM10 emissions.
50% of the total NZ electricity consumption goes into space heating and we are fast learning that a 2000w radiant heater is a poor substitute for a heat pump, assuming you have the capital available to choose between the two.
If 25% of ‘existing model’ wood burner users switched to electricity heat pumps, the annual health SAVING would be $180 million by removing an estimated 50% of PM10 emissions.
If all ‘existing model’ wood burners were replaced by heat pumps then the SAVING in lives and health $$ would be immeasurable.
As shown above, the increased use of wood can lead to increased health effects, unless very clean burning appliances and fuels are used - these are not commonally available yet.
This is a dilemma, since it leads to contradictory outcomes:
A) Use more wood for heating = displacing gas and thermal electricity generation = lower CO2 emissions.
Good for the global environment (IF you believe that anthropogenic CO2 is a problem - I don't).
B) Use more wood for heating = increased air pollution emissions = increased health effects on the urban populations.
Bad for the local environment, and increased health effects.
So which is the better more ‘sustainable’ choice?
The above is précised information from the following reference papers:
Posted 12 Jan '10 07:53 AM
Perhaps we should all switch to pellet fires, emissions are in the 0.5 - 0.6 g/kg for these types of wood burners.
Posted 12 Jan '10 09:45 AM
If these figures were correct and if we could all afford the cost of using the most expensive fuel (currently) of pellets, then you would have a fair point.
But I understand the figures you quote are for a theoretical perfect combustion which according to the NZ link below cannot be achieved in practice.
The best ‘mean’ efficiency averaging only the three best performing pellet burners currently available, was 1.43g/kg with a 95% confidence factor.
Current pellet burners would still have an annual health COST of about $20 million from PM10 emissions against an annual health SAVING using Heat Pumps of $180 million.
What price do you put on your loved ones dying of cancer from PM10 particulates?
Some of you will know that I am speaking from experience.
Posted 12 Jan '10 09:53 AM
Link did not transfer properly - here's hoping this time -
Posted 12 Jan '10 07:03 PM
Hope you are well and adapting well to your new regime.
I wonder if PV (when their price falls enough) would be able to drive heat pumps for space heating, with either battery back up for evenings (very large battery system!!) or with thermal storage of some sort (phase change material probably)?
Posted 12 Jan '10 07:32 PM
We had to choose between a heatpump and a woodburner for our house as well and it was a very difficult decision.
At the end, we decided to go for a woodburner, a kent Kiwi Rad "Clean Air", for various reasons.
1) You can cook on it during power outages, or simply because it is on and hot anyway - saved gas for cooking
2) It is a radiant heater, exactly what we needed for the big open double hight space, any type of air heating device (incl. heat pump) would not be that effectife due to heat rising up - ergo cold ground floor
3) It has emissions of only 1.2g/kg (yes, lab test, I know)
4) We have plenty of wood around
5) You have to work for your heat
6) It is a kindof "natural" heat, something you can relate to, something for your soul so to speak
I believe the efficiency in our place is higher than the stated 70% because the flue runs trough two storeys, the idea was to also heat the upper storey via the flue, but we have been a bit disappointed because the upper flue is almost cold at ceiling level, so virtually no heat escapes unused.
My personal problem with heat pumps is that they generate heat (and cold) too easily at a push of a button. People tend to put them on more often or have them running automatically.
Some of our friends have it running in winter and doors open, maybe not thinking about it, not realising it or whatever. You tend to forget about those things. "Set and forget" seems to be true....
Posted 12 Jan '10 08:00 PM
I have friends in Paraparaumu, whom had a heat pump installed, electing to not use the wood burner as its too messy to use. Now the heat pump runs with the windows etc open as its just another electrical appliance (like a light) forgotten about.
You are correct Ingo.
Posted 12 Jan '10 09:54 PM
Hello Igno and Mike,
It may seem to you all that I am condemning Low Emission Wood Burners and promoting Heat Pumps – I am not.
If I told you that I am very much in favour of coal fired power stations and rate them equally against low emission wood burners, you would say - “What, are you mad!”
But a coal fired power station can easily be fitted with SO2 ‘scrubbers’ and ‘fabric filters’ to remove 99% of all pollutants before they reach the flue stack. All that is then emitted is ‘beneficial’ ( my contention) CO2 and H2O.
Why then can we not have Regulation, which I hate, but accept as necessary, to do the same for our residential Wood Burners.
I do not know the technical pressure requirement to force wood burner flue gasses though a Diesel Particulate Filter (maybe a reader will enlighten us), but I do know that 99% of the pollutants can be removed in this way.
Then it all comes down to economics vs heath.
I await your comments.
Posted 12 Jan '10 09:59 PM
Only two spelling mistakes - Igno should read Ingo and economics vs heath should read health.
Sorry - Rex
Posted 13 Jan '10 12:57 AM
Nelson inventor has designed a device to enhance wood burner efficiency, see link, seems local council don't want to know about it, typical of small minded NZ.
Posted 13 Jan '10 09:17 AM
I think you are a bit hash on the Nelson Council “not wanting to know” about Neville’s “Flue Cap” as they clearly stated they would change their Regulations to include this currently untested component, once it had been tested for the following:
Safety – the claim is that the fire now burns hotter and more efficiently. Does this increase a single flue temperature to the emissivity required for a double or even triple skin flue requirement?
If a fire burns incorrectly lacking oxygen, then poisonous carbon monoxide can form.
I would want some scientific reassurance that this could not occur.
Performance – what %g/k of exiting gasses and particulates are removed – Neville may be accurate in his claims that they are equal or better than current approved models, but this has not been independently confirmed as yet.
I side with the Council, but hope that Neville can find a financial backer to complete the approvals, after all, every solid fuel burner from anywhere in the world has to meet these test requirements.
I am glad we are starting to think outside the square to solve the PM10 emission problem as the answer to my thread question, is not which type of heating unit you choose, but what emission comes out of it that matters.
Posted 28 Jul '11 11:28 AM
Neville's FlueCap has gone through the only available expert testing - which is rubbish. Thank you Ross Sneddon. Although Mr. Sneddon has a vested interest in relationship with the change-out scheme with an opinion that the FlueCube could overheat the "fire below it" this did not show up in the "scientific" test results at all and he did not fully understand the science behind what makes it so effective.
Every published claim about the FlueCube has been observed by not only the developer but the close to 200 people who have had it installed. There are many testimonials on the product's website. Because the ratings given to the purchaser by qualified government testing can only be achieved in the carefully manufactured ideal heating environment it was necessary to design something that could make these ratings true in the field.
Here's the catch and why it isn't just a simple case of 'getting it tested'. As the inventor and knowing his product better than anyone else Neville refused the council in only installing it on their new certified wood heaters. Why? He has principles. He knows it works on pre 1994 burners and he was one of many that would have to pay thousands in replacing perfect performing appliances. The science that says it's the non-certified appliance's fault is bunk. Look it up. Why do authorities keep preaching the testing on this safe invention? - because there isn't any test. H Cowls and many other cowls that suggest improvements are not individually certified to a council standard equal to what the councils ask for in this one.
The councils and standards technicians are protecting their right to certify and replace. Neville has a clean air solution in good faith and is sticking to principles that protect the public interest.
200 sold. 100% positive feedback returned. Renewable low emissions heating is looking good with wood. Another important environmental fact to point out is a wood heater appliance and its parts are almost 100% recyclable. Is a heatpump?
Posted 14 Jul '18 06:56 PM
All wood burner pollute - some just more or less. Read the Danish study from 2016. Try thinking a .22 vs a .38 bullet - they both will kill you.
Go heat pump and insulation.
Posted 18 Mar '20 10:17 PM