Biomass operations on the Hadlow Estate

It is important to us that we embrace the opportunity to produce energy sustainably.

As a society we are all too aware of our rapidly changing climate and the need to reduce carbon emissions – such issues have been brought to the forefront of everyone’s minds following this month’s COP26 summit in Glasgow.

One of the ways in which we are evidencing our commitment to this, is through the use of a biomass boiler at Hadlow Place Farm, which is supplied by wood and woodchip produced in our forestry operations.

The boiler feeds a small district heating system and provides heat for a number of our buildings and houses.

It has been working for seven years and in that time almost all of the energy used in the system has been produced by woodchip – 91%. Less than 9% of the system’s energy is produced by gas, which is only used if there is particularly high demand or back-up power is required – for example, if there is a problem with the boiler.

There are eight buildings supplied by the biomass boiler including Hadlow Place, Hadlow Place Farm office, the new accommodation for one of our farm team and four cottages. Annually, the total output of the boiler is more than 30,000 Kwh.

Our Woodland Manager Rick Vallis looks after almost 1,000 acres of woodland across the Estate, an area which includes both broadleaf and coniferous trees.

Rick says: “The timber used for the biomass operations is wood produced from our own woodlands as part of ongoing harvesting operations, such as the thinning of conifer stands or coppicing of sweet chestnut.

“It’s a carefully and sensitively managed process, with all works planned and approved in advance by the Forestry Commission and agreed with the RSPB, which manages much of the woodland area as a nature reserve. As part of our harvesting plan, any felling work we do is done from September onwards, once the bird nesting season is over.”

Thinning and coppicing operations are planned according to the age and quality of the timber crops within the woodland. Lower quality material is selected for the wood-chipping process, while the better quality timber will be sold on to local saw mills for conversion to sawn timber produce, or fencing material.

In thinning operations, specialist forest machinery is used to fell the selected trees. A harvesting head is used to clamp the bottom of the tree whilst a chainsaw cuts and fells it. The log is then picked up and measured to check if it is the right size and quality for the saw mill, before being cut into specific lengths. If the material is small or not straight enough it will be used for chip-wood and eventually converted into wood fuel.

It’s some time though before this wood will be chipped, as Rick explains: “The timber set aside for wood fuel must be given time to dry out, as excessive moisture will limit its effectiveness when it is burnt in the boiler. The wood will be left to dry for an average of 18-24 months dependant on the tree species which have been harvested.

“As a guide, we look to produce 175-200 wet tonnes of wood per year. Once that has dried out and is ready to be chipped, this will equate to around 125-150 dry tonnes. Annually, we will burn an average of around 120 dry tonnes of chipped wood.”

When the logs are sufficiently dry, the chipping takes place at various locations throughout the Estate woodlands before being transported back to the farm, where it will be stored and gradually used throughout the year. As they’re needed, the chips will be fed into the boiler and burned, generating heat and hot water.

Rick adds: “By utilising Estate grown timber our wood fuel production cost is as low as you can get, so commercially it’s a sound thing to do. Alongside the obvious environmental benefits of using biomass as an alternative to gas, it’s also a very sustainable manner in which to manage the Estate woodlands.

“In the future and as part of our woodland management plan, we will be gradually converting areas of mature conifer plantation to native broadleaf species and any replanting undertaken will always incorporate an element of those species suitable for our wood fuel supply chain.

Harry Teacher of the Hadlow Estate said: “When we installed the biomass boiler in 2014, we wanted to see if it would be manageable and most importantly, sustainable in the long term. This approach of using sustainably grown timber to supply energy locally, allows us to invest back into our woodlands for the long term. We’ve certainly burnt a lot less gas as a result and when you consider the rising cost of gas and oil, it’s an obvious choice.”

Harry says that there are also benefits for wildlife and biodiversity: “The careful management of our woodlands and the thinning work that takes place creates a diverse range of habitats for insects, birds, wildlife and plants, by opening up the forest floor and allowing light to flood in. This creates a mosaic of habitats across the woodland, helping a range of different species to thrive.”

Alongside biomass, seven years ago the Estate also brought forward plans for a solar park to generate low-carbon electricity. Harry said: “Over time we’ve been able to learn about the relative benefits of both biomass and solar and while each has a role in helping reduce our carbon footprint, we think solar brings greater benefits, particularly at the scale we’ve been operating at.

“All else being equal, it seems to us that biomass would be even more effective on a larger scale, with a bigger boiler serving more properties.”