Our renewable energy projects

Tending to the biomass boiler

We’ve been busy installing a biomass system to provide heating and hot water to buildings on site. Not only will this provide a cost-effective way of consolidating the existing heating system, it will reduce our carbon footprint and protect Sizergh from the current rising cost of fossil fuels.

Following on from the biomass system, solar panels will be installed on the roof of the visitor centre this summer, 2022. These two schemes, when added to all the other renewable projects happening nationally, will mean that the National Trust will generate 50% of its energy from renewable sources by the end of the year.   

Here’s a bit more about what we’re doing and why we’re doing it.

Biomass heating system 

What is a biomass heating system?

Biomass heating systems use renewable energy sources – most commonly wood pellets, chips or logs – to power central heating and hot water boilers. These sources still release carbon dioxide when burned, but produce considerably less than fossil fuels. 

How does it work?

Wood pellets are fed into a combustion chamber where they are burned. This produces hot air and gas which passes through a flue, then through a heat exchanger, which transfers this heat to the water. 

How biomass works
Diagram of how biomass works
How biomass works

Why choose biomass and where is it?

Using one biomass system to produce hot water and heating for the entire site is more sustainable than the current nine gas boilers in situ. Initially a feasibility study was carried out to see which technology was a ‘best fit’ for Sizergh. The study showed that biomass was most suited to Sizergh due to the constraints of the archaeology around the castle (there are centuries-old foundations and buried footprints of long gone buildings which need to be preserved) and the need for maintaining a high temperature within the castle for conservation purposes. Having limited room for plant and pipework within the listed grounds and castle buildings, we found the ‘Wash House’ at the entrance to the garden provided the perfect location for the biomass boiler. 

Piping being laid along the lane behind the visitor centre
The image shows a digger next to a newly dug trench, where insulated pipe is being laid
Piping being laid along the lane behind the visitor centre

What fuel will you be using?

To reduce our reliance on fossil fuels, we will be using wood pellets, which are EN Plus A1  standard and 100% sourced from UK sustainably managed woodlands,. This also provides a secure supply of fuel which is a critical issue in the current climate. As the ageing gas boilers needed replacing soon (which would’ve cost around 50% of the entire biomass project budget) it was a perfect time to do this.

Is cutting down trees bad for the environment? 

Tree felling and coppicing, when they are carried out as part of a sustainable forest management plan, is good for the woodland environment, and mimics events which would happen in a natural forest. In addition, more trees will be planted out on the estate to offset the carbon released due to burning the pellets.

You sell firewood, why can’t you use the wood from your estate to power this system too?

Unfortunately, it’s not possible to use our own wood from the estate to fuel the new biomass plant, as the process of converting felled wood into high quality pellets needs space, equipment and time which we don’t have. It’s more cost-effective to buy in these pellets from a manufacturer which specialises in their production. It is possible to use woodchip (rather than pellets) but this also needs careful processing and lots of storage space, however the boilers are adaptable to this so it may be something we’re able to look at in the future. We will continue to supply firewood to surrounding rural communities, helping offset oil and other fossil fuel use in the area. This firewood is sourced from our woodlands following coppicing and other management techniques which support biodiversity. 

What money will be saved as a result of using biomass?

The project will benefit from the government’s Renewable Heat Incentive scheme, a financial incentive put in place to promote the use of renewable heat, paid over the next seven years. As well as this, we will also save money on escalating gas prices. These savings will help fund future conservation projects.

When will the project be finished?

We hope to be up and running by the end of April 2022.

Are you considering any other renewable energy sources for the future?

Yes. 50 kW of solar panels will be installed on the roof of the visitor centre, providing electricity for the café, shop and visitor welcome area. We intend to start the work this spring or early summer and hope to significantly reduce the amount of electricity we need from the National Grid. 

Solar panels or photovoltaics (PV)

How much money will you save?

It’s really difficult to say precisely how much we will save given the unpredictable energy markets at the moment, but we will have a better idea after the first year and make comparisons. However, it’s not all about saving money – the purpose of installing these panels is to move towards greener sources of energy.

A picture of solar panels fixed on the roof of a building

Can you sell the electricity back to the grid? 

Not at the moment. Our aim is to use most of the electricity generated on site and reduce our dependency on the National Grid. This cuts down on our energy costs as well as our carbon footprint.

Can you store it? 

No, we don’t have any plans for battery storage immediately because we predict we’ll be consuming most of the electricity as it is generated (i.e., when Sizergh’s at its busiest in the summer months). However, we are looking at battery storage more generally across the National Trust as an organisation.