The Press and Journal (Inverness, Highlands, and Islands)
A lean, green ice
Aproject to build one of Europe’s greenest and most ambitious refrigeration systems is under way at an Aberdeenshire family farm. Mackie’s of Scotland has taken delivery of the first parts of a £4.5 million investment in equipment that will increase and improve its ice cream production, while also reducing the firm’s carbon footprint as it strives to become “the greenest company in Britain”.
The project was made possible by a £2.05m grant from the Low Carbon Infrastructure Transition Programme. The Scottish Government support, part-funded by the 20142020 European Regional Development Fund programme, is matched by an investment of more than £2.5m by Mackie’s.
The company, based at Westertown Farm, near Rothienorman, is targeting carbon dioxide (CO2) emission cuts of up to 80% and energy cost savings of 70-80%.
Managing director Mac Mackie said: “This freezer can be the final piece in the jigsaw to our farm becoming entirely self-sufficient in renewable energy.
“With our solar farm, wind turbines and existing biomass system powering 70% of our annual energy needs, the next stage was to look at ways of slashing our energy requirements.
“We first set out on the journey towards this refrigeration back in 2018, and are grateful that the support from the Scottish Government and European Regional Development Fund will enable us to make this happen. It should create an exemplar low-carbon refrigeration plant for Scotland.”
Unlike some systems that use environmentally damaging HCFC gases, Mackie’s new equipment will run on ammonia, powered by hot water from a large biomass boiler which, through an absorption chiller, will cool to -15°C, with minimal electrical input.
Where necessary, conventional refrigeration compressors will reduce the temperature further to -30°C.
The system will provide the temperatures needed at all stages of the production of Mackie’s famous ice cream, as well as delivering carbon and electricity savings.
It is expected the new quicker and colder way to freeze ice cream will bring further benefits to the business – improving the quality of the product, while also helping the firm to ramp up output to meet growing demand.
Mr Mackie added: “This is a truly exciting development for us. Being able to produce more, higher quality ice cream is just another bonus resulting from our investment in further green technology.”
Mackie’s already produces more than 2.2m gallons of ice cream a year. Its renewable energy is derived from four wind turbines that produce 8,500 megawatts per hour (MWh) of electricity every year and also its 7,000-panel solar farm, once the largest in Scotland.
The new equipment will include replacement refrigeration plant, an absorption chiller, two biomass boilers, two new ice cream freezers, an ice machine and bulk content “spiral” freezer.
Ammonia will be used to run all the equipment apart from the spiral freezer. CO2 will be used as the refrigerant gas in only the spiral freezer, with biomass boilers the principal energy source.
According to Mackie’s, there are three main reasons why the new system will have a lower carbon footprint than its existing equipment.
Firstly, in addition to providing energy for the refrigeration plant, the biomass boilers will provide heat for mix tanks, pasteurisation and cleaning processes within the factory, replacing an existing oil boiler.
As biomass fuel has a much lower carbon footprint than fuel oil, this will be a large carbon saving for the company.
Secondly, the existing system uses electricity as the energy source for the refrigeration process. The new system uses heat from the biomass boilers as the energy source for the refrigeration processes down to -15°C.
Conventional compressors are needed only for the extra step down to -30°C. Electricity costs for the new system will, therefore, be around one-quarter of those for the existing equipment – another significant carbon saving.
Finally, the current system uses refrigerant gases with a global warming potential nearly 4,000 times that of CO2.
The new system will use mainly ammonia and some CO2 as the refrigerant gases. Ammonia and CO2 have a global warming potential of zero and one respectively, relative to CO , a 2 significant reduction.
Ammonia was first used as a refrigerant in the 1850s in France. It remained a popular refrigerant for decades until synthetic HCFC gases became dominant.
But in recent years there has been a resurgence in interest in ammonia, either alone or in cascade systems with other gases such as CO2, as the ozone-depleting and global warming potential of HCFCs has been recognised and reflected in industry regulation.
Overall, during normal operation, the carbon footprint of Mackie’s new refrigeration system is expected to be around 20% of that of the existing equipment.
The Mackie family’s farming history in Aberdeenshire goes back at least four generations but today they are best known for their ice cream, made with milk and cream from their farm.
They diversified into making crisps in 2009 and added a dedicated £600,000 chocolate factory to their business in 2014.
Mackie’s, which also makes popcorn, has since achieved substantial new contracts for its chocolate, including deals with Tesco, Sainsbury’s, the Co-op, Morrisons and Asda.