Duffryn

Sorry been out all day. Yes I meant charging a gate fee on burning waste wood. The GF boiler is perfect for this in that it is accredited to burn "Waste wood with a moisture content of <18% based on both grade A and mixed municipal, construction/demolition and commercial classification from DEFRA 2008 - Waste Wood as a Biomass Fuel". Plus it has a large fuel chamber that permits loading by forklift.

I should have related this to drying times. Based on an average of 100kwh then I would expect a 40ft kiln to take roughly 6 days to dry 32m3 of logs. So 5.7 tonne of fuel per drying cycle for an income of £780

As Ashley said there are a number of variables here. The figures below are based on the Glen farrow boiler which is the only batch fed boiler I have a great deal of experience of. The comments are not a criticism of Glen Farrow my understanding is that most large batch fed boilers will deliver similar results. If we take a 200kwh boiler, the rating relates to its peak output. Out of a 200kwh boiler you would realistically on expect to get 120kwh an hour maximum over the course of a day, probably less so let’s work on 100kwh. Wood at 20% m/c has circa 4.2kwh per kg . Source Energy Cost Comparison | Nottingham Energy Partnership So a tonne of wood at 20% m/c has 4,200kwh of energy in it The boiler will only be 60% efficient. So out of the 4,200kwh you will only generate 2,520 kwh. Working at 100kwh output from the boiler you will use a tonne of wood every 25 hours. Based on the current medium tariff ( boilers over 200kwh) you would generate 5.18p per kwh. So every 25 hrs you would be paid £130 for a fuel cost of 1 tonne of fuel. I have used the medium tariff because most manufactures now offer a boiler just over 200kwh to ensure you get this. The key to making the figures add up here is to use “free fuel” or getting paid to burn the fuel as I know one entrepreneurial user is doing.

Having multiple boilers like that reduces the headache of refueling in that if your refueling 24/7 the same man can refuel multiple boilers for effectively no extra cost.

19 years time, who knows, suspect by that time it will be pointless, the market will be based entirely on imported kiln dried and the cost price of hardwood in the UK will mean we are powerless to do anything about it.

Couldn't agree more. Ripping out current woodburner in new house and putting in another Morso, without doubt the best woodburner i have ever owned.

LogPro assumed an 80% efficiency (as per manufacturer claims at the time) where as we learned the reality with a batch fed boiler is closer to 60%. If you can run a batch fed boiler on waste wood / straw and claim RHI then its is still a wise move so long as you are around to keep loading it. Oil cost - assuming 3.5 day trying time for a 20ft container ( 16m3 of logs) with 100kwh of heat going in and oil at 20p a litre you would be looking at :- 8,400 kwh / 10kwh per litre is 840 litres so £168. Plus say 5-10% for efficiency loss then circa £180. Oil is at an all time low and I would hate to invest in an oil boiler for a kiln on the assumption that costs would remain at 20p a litre. To do the same on chip 8,400kwh at 2.2p per kwh = £184

I don't see any point in splitting hairs. The point of the post that generated these comments was to show that oil just doesn't add up when taking into account RHI and it doesn't regardless of the efficiency of the boiler.

Honest answer is that I don't know but even if it were 5p a litre cheaper it still wouldn't pay over biomass with RHI now let alone when oil prices go back up

Thanks but a small donation to the charity and retruning the favour to someone else would be more than sufficient

Oil boilers are typically 95%+ efficient. My comparison was broad brush and designed to show that Oil doesn't pay when the RHI is paid on biomass .

It gets harder to dry the lower the m/c. There is also an elapsed time to get the logs heated up in the first place ( hence the importance of keeping the heat in the kiln 24 /7). If you are putting them in at 25% I would estimate 24 hours to get to 20%. Personally I think a better use of the kiln would be to dry green wood from scratch. This would enable you to free up cash tied up in stock and yard space and would involve less handling. If you want some pointers on kiln design, pipe work and control setup then let me know. I can save you a fair few ££'s and a great deal of headache pointing you in the right direction and the Arbtalk Childrens Trust charity would always appreciate a donation !

You have got a bargain there ! My costs are not dissimilar using my own wood ( allowing for cost I would have sold it for) and having it chipped

Nice boiler ! I would double check with your installer but given that demand for the other heat uses on the site will be minimal during the warmer months then your existing setup should "walk" handling a 100kwh kiln.

£60 per tonne assumes you are buying green wood, seasoning it and hiring in a chipper ? Assuming above assumption is correct re cost of fuel then Woodchip at 30% is c 3500 kwh per tonne. Boiler will be max of 90% efficient so 3150 kwh per tonne or 1.9p per kwh.

What are the calcs on that ?

For the benefit I don't think the costs would add up ???? Have you tried turning the fans right down to the minimum ? Have you looked at increasing the size of the accumulation tank ?

Which woodchip boiler do you have ? Whats is the capacity of the boiler and what is the size of the water jacket around the boiler ?

Heating oil is 20p a litre locally. Energy is 11kwh per litre so 1kwh will cost 1.8p. Woodchip would cost circa 2.8p per kwh. Conclusion excluding RHI then heating oil is way cheaper and easier. Factor in RHI on med tariff and its a different story. The big risk with oil is of course the price shooting back up again. Writing this after a couple of glasses of wine so sorry if maths is out !

Lancer - With a woodchip boiler delivering 100kwh constantly and a 20ft insulated kiln you would dry 16m3 in 3-4 days for a lot less fuel. The more and more I think about your situation I think you are better off using your existing woodchip boiler.

If you went for a 20ft insulated kiln with 100kwh of heat exchangers and a greater than 200 kwh boiler I would guess you would be looking at £40-£45K all in and allowing for some building work. In terms of accumulator tank , I think from memory its roughly 70kwh per 1500 litres. So depending on the choice of fuel and thus the refueling times you would need a tank of between 10 to 20,000 litres. You would get circa £14K of tier 1 income from it a year but would need to deduct fuel and labour cost from this. Running the same setup via your woodchip boiler (cost of kiln £8k) and depending on how much your paying for your chip you would just about break even on the tier 2 income covering your chip cost. The key to making the batch fed boiler work is the availability of labour on site and fuel cost ( boiler will only be 60-70% efficient compared to your woodchip boiler of c 90%).

Amending the RHI or a new commercial heating use on an existing accreditation is easy, just give them a call and they can talk you through it. Are you using all your tier 1 at the moment ? If so might be worth considering a new batch fed straw fueled installation with a large accumulator tank. This would give you a much better ROI

james cagney

joan collins

jimmy cricket