Ready to Burn – providing a solution to improve air quality
18 December 2019
Ready to Burn – Providing a solution to improve air quality
The Ready to Burn scheme has had some great success but there is still a huge opportunity to further improve the environmental impact of wood burning through consumer education. It’s critical that we continue to highlight the benefits of using dry Ready to Burn wood and the dangers of burning ‘wet’ wood.
Woodburning stoves have become a popular way to help heat our homes. For parts of the year they can provide all that is needed, whilst in the colder months they are a great way to supplement a main heating source. A wood burning stove can provide an efficient and low carbon emission heat source when fuelled with the right quality, dry wood fuel.
The origins behind Ready to Burn came about from needing to combat the increasing sales of wet wood fuel being sold by garage forecourts, DIY shops, garden centres etc. Whilst it might appear obvious that wood should be dry before attempting to burn it, the lack of information and awareness provided with small retail bags of wood fuel meant wet wood fuel was regularly being sold for immediate use on stoves and open fires. The consequences of high emissions from burning wet wood have helped promote the bad publicity that woodburning stoves are a major contributor to poor air quality.
Any combustion appliance burning the wrong fuel will create excess emissions. For wood burning on any appliance a simple transition from burning wet wood to dry wood can make massive improvements. The Ready to Burn scheme promotes and recognises wood fuel suppliers and re-sellers offering Ready to Burn fuel with a clear logo and supporting information helping consumers make the right fuel choice.
With the successful growth of the scheme, we can be much more certain that the wood fuel sector can be part of the emissions solution – not part of the problem. Misleading media reports have resulted from the fact that understanding where pollution comes from can be complex. Using the results of research and testing carried out by Woodsure and HETAS, together with other academic research, we can start to give some facts and benefits in the transition to burning dry wood fuel.
The wood-fuel sector is served by a variety of businesses and organisations and it has always been very difficult to pin down the size of the domestic market. Since the start of the Ready to Burn scheme and with support from the stove and wood log fuel industry, those early adopters of Ready to Burn, together with Defra and others, we started to gather information to estimate where we started from and to measure improvement over time. This has revealed some interesting facts and estimates:
- There are approximately two million solid fuel appliances in domestic properties in UK
- We believe around 1.8 million tonnes of log wood fuel is being burnt in the UK on domestic appliances, with a significant proportion unaccounted for e.g. either sold for cash, foraged or obtained FOC. However, this is far less than a DECC survey a few years ago which indicated a 4.8 million tonne provision
- This is one key reason we feel the weight of particulates said to come from domestic solid fuel burning is likely to be overstated by previous reports based on the old estimate of 4.8 million tonnes estimate.
- It’s likely that half of the wood burnt in UK homes is burnt on open fires or old stoves
Soon after, Defra’s clean air strategy was released, promoting Ready to Burn and setting out the need to control wood burning to reduce the environmental impact through reduced emissions. The Ready to Burn scheme was seen as a mechanism to regulate the sale of wood fuel and promote the message of responsible burning.
The current Impact and potential improvements
Research from Leeds University into using different moisture wood fuel on a wood burning appliance, together with well-established good burning practice, they concluded that the emissions from wood burning were lower when burning fuel up to 20% moisture content. This research helped to establish the Ready to Burn moisture limit.
This research also provided indicators about the potential environmental benefits from this 20% limit. A sweet spot of 8% to 20% moisture for wood logs gives lower particulate matter (PM) emission. It also reduces levels of other pollutants and increases combustion efficiency. These are big wins all around.
Laboratory test results vary with appliance type and fuel type (including species). On average, wet wood fuel at 30% to 40% moisture will still burn but has demonstrated to give up to five times the particulate emissions of dry wood, even in a simple open fire.
The table below shows laboratory test data comparing dry wood against wet wood on an open fire:
|Dry Wood on open fire
|Wet Wood on open fire
|Mean Smoke Emissions g/hr
|Mean Smoke Emissions g/hr
Extracts from reports carried out by accredited Laboratory
Further research earlier this year commissioned by HETAS with the support of the Stove Industry Alliance (SIA), further demonstrates that there are cost benefits of burning dry wood fuel through real heat benefit, as well as the fact that burning dry wood is kinder to appliances and chimney systems.
We can account for around 0.4 million tonnes of dry wood sold. If the balance of the estimated 1.8 million tonnes of log wood fuel being burnt in the UK, moves from wet (40% moisture) wood fuel burnt on inefficient appliances to dry (<20% moisture) wood fuel burnt on modern stoves, we could make significant savings on emissions and the amount of fuel burnt to produce the same heat energy.
Forestry Commission statistics provide the following energy output from burning wood:
- Heat produced at 20% moisture content = 4.086 MWh/t
- Heat produced at 40% moisture content = 2.895 MWh/t
These heat outputs together with measured efficiency from appliances burning wet and dry wood, the benefits are multiplied again. An open fire burning wet wood could release only 6% of beneficial heat to the room, compared to 75% beneficial heat to the room from a modern stove burning Woodsure Ready to Burn wood.
Therefore, moving 1.4 million tonnes of 40% moisture wet wood burnt on open fires and inefficient stoves to Ready to Burn wood burnt on efficient stoves could save an estimated 2900 tonnes of PM per year.
You can find Ready to Burn suppliers using the Woodsure website postcode search.