Project lead: Rosemount Farms
Project partners: SLR Consulting
Area: Angus
Main technology: Creation of a new fuel source
Local Energy Challenge Fund grant awarded: £212,000
Background
The Montrose Local Energy Project sought to create a new fuel source from a waste product – animal bedding. Working in collaboration with a number of consultancy organisations and a farm in Angus, the project aimed to use waste animal bedding to produce pellets as a viable heat source.
The project faced several challenges because it was extremely innovative in creating pellets of this kind. The waste bedding must be dried and processed before being turned into pellets, with a view to selling these pellets on a commercial basis.
Project aims and outcomes
The team carried out trials to test the concepts of drying, pelleting and then combustion of the used animal bedding.
The team took the bedding and used a STRONGA FD30 continuous dryer at Kinknockie Farm. Here they were able to dry 22 tonnes of the bedding from 69% to 20% moisture content. There were issues with the material clumping into balls in the dryer and further drying was also required to reduce to c.15% required for pelleting. They used equipment at Harpers, a wood recycling centre, to turn the 10 tonnes of dried bedding into pellets.
First, stones and metal were removed by an Air Density Separator, then it was milled to produce a consistent feed. Both a large scale and small scale pellet mill was trialled to create the pellets and both worked well. The pellets were hard, shiny and did not crumble easily. The team chose to mix the bedding with sawdust to improve the moisture and energy content of the pellets. They trialled various mixtures contained 0%, 25%, 50% and 75% sawdust. Combustion of the pellets raise some challenges.
All of the pellets caused periodic blockages in the feed screw conveyers that supplied the fuel to the boiler burner. The 50% and 75% sawdust pellets were the only mixes that would combust at a steady state, though even these pellets had high levels of CO and NOx in their flue gasses. The ream sought to organise further boiler trials to see if these issues could be resolved, however this was not possible due to time constraints.
Looking ahead
The project is aiming to achieve capital funding for Plant Design and Installation and then use this funding to install and trial a farm scale plant at Pettycur Farm. If successful, it will try and scale up to larger scale “hub” plant to process bedding from multiple farms.
Contact
This project was managed by Euan Munro on behalf of SLR Consulting Ltd.
T: 0131 335 6830
E: eamunro@slrconsulting.com
Read more in the case study and executive summary report.