Distilling the zero carbon benefits of heat pumps

IRELAND: An Irish distiller is now producing carbon neutral whiskeys following the installation of high temperature heat pumps from Finnish manufacturer Oilon.

The Ahascragh Distillery, about a two-hour drive from Dublin, is located in a 200-year-old brick mill where grain was ground into flour from the early 1800s until the 1950s. Now, this historic building, which reopened its doors in the summer of 2023, has been given a new life as a carbon neutral whiskey distillery.

Distilling whiskey is very energy intensive. Each bottle of traditionally distilled whiskey produces 3-4kg of carbon dioxide emissions. Unlike other distilleries in Ireland, heat is provided to the Ahascragh Distillery through heat pumps which means that there will be no flue related emissions, or impacts on the local environment. 

In Ahascragh, the heat needed for the process is produced by high temperature heat pumps instead of natural gas. The heat pumps are powered by wind-generated electricity. 

“In this way, we have been able to get rid of fossil fuels and the process has become zero-emission,” explained Ahascragh Distillery owner Gareth McAllister.

The heat pump design, heat recovery and thermal storage means that the energy inputs to the distillery are a third that of traditional technology. 

Finnish energy technology company Oilon delivered two P450 series heat pumps and one smaller P150 heat pump to the distillery. P450 series units are capable of producing temperatures of up to 120ºC. In Ahascragh the design temperature is 115ºC. 

Oilon’s experience in process industry heat pump solutions was utilised in the project. The Dublin-based carbon-neutral turnkey solutions company Astatine was responsible for the overall design of the system.

Two parallel processes work in the distillery: the actual distillation process where alcohol is alternately steamed and condensed in a closed circuit, and the automatic cleaning process of the equipment, which requires a significant amount of warm water.

“The total COP has been raised to an exceptionally high level by applying the operating methods of the process industry: heat pump technology is combined with process know-how, ie all generated waste heat is recovered with the pumps and utilised at another point in the process,” Astatine’s manager Tom Marren said.

At the high temperatures of the P450 pumps, the distillation process itself is running. In this process the alcohol alternately vaporizes and condenses in a closed circuit. The pumps are equipped with separate heat exchangers which also produce lower temperature water for the washing process. The smaller P150 pump produces domestic hot water which can be used for additional cooling of the distillation process if necessary.

“Comprehensive system planning and combination of processes was crucial in terms of COP and, of course, reducing emissions,” explained Oilon sales and marketing director Sami Pekkola. “The total COP of the process is an astounding 6.5.”