A lot of firewood businesses have moved into producing kiln dried logs over the last 12-24 months, many of them mis-represent the moisture contents of kiln dried V air dried stating that air dried logs have a Mc of 40%+ whilst kiln dried will be 20%- the truth is any log which is properly seasoned will have a Mc below 25% which is the top end of the target zone whether it's air or kiln dried. In a 2011 study by America's EPA they found that domestic stoves burning fuel below 15% or above 25% were actually polluting the air and to get the best value for your money and the air quality you should burn logs between 15% and 25% mc. http://www.epa.gov/burnwise/workshop2011/WoodCombustion-Curkeet.pdf
some of the differences are:
Air dried logs - require long term investment in your business as you need to produce the logs 6 to 24 months in advance to reach the optimal Mc depending on species.
Kiln dried - you can reach the optimal Mc in 3 to 10 days.
Air Dried - UK grown generally
Kiln Dried - in many cases it's a Baltic state import with several thousand miles of Transport on the crates.
Air dried - Uses the sun and the wind to Season the logs.
Kiln dried - Uses wood to force dry the logs, for every 1 tonne of logs being dried upto 250kg of fuel will be used to run the kiln.
A one kilogram log of wood offsets carbon dioxide emissions by 1.65 kilograms.
1kg (wood) x 0.45 (carbon content) x 3.67 (CO2 / C) = 1.65kg CO2 reduction. This result gives an idea of how important trees are to remove carbon dioxide from the atmosphere and why it's a bad idea to use them to dry your logs.
Thats 1.65 tonnes of CO2 for every 1 tonne of wood dried in a kiln V's 0 for air dried logs.
as the Forestry Commission put it in their biomass pdf, Kiln Dried logs will have used considerable energy in production.
About the Subsidy
Air Dried - no RHI payment from the government.
Kiln Dried - RHI payment of 7.6pKwh with kilns of 175kwh upwards in use or in otherwords your taxes are being used to pay some merchants to run kilns to dry their logs on a level if they have enough kilns they don't actually need to sell the logs they can live of the subsidy payments.
Air Dried - Logs dried in an ethical and totally sustainable way giving a low carbon environmentally friendly fuel.
Kiln Dried - Maximum profit with no ethos and has a negative environmental impact.
As with many things it comes down to individual choice, for some it's about the price others it's about the environment, we just ask that you give 30 seconds of thought next time you order your seasoned logs to which method is most important to you.
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