By Richard Gueterbock, Clearfleau Ltd

Food processing businesses should be looking for alternative, cleaner sources of energy for their production processes.  Generation of biogas from processing residues offers a cost-effective way of reducing emissions and environmental impact.

Clearfleau has installed industrial bio-digestion plants on British dairy, food and drink production sites.  On-site anaerobic digestion (AD) will transform the handling of bio-degradable residues and washwaters, generating biogas to supply low carbon power or renewable heat to production processes, or for upgrading to biomethane for grid injection.

Anaerobic Digestion is a bio-chemical process, where bacteria break down organic material in the absence of oxygen to produce biogas (mainly methane (CH₄) and carbon dioxide (CO₂)). On-site digestion enables food manufacturers to use the latent energy content in their residues, providing an attractive payback, by cutting disposal and energy costs for factory sites.

However, businesses need some persuasion to adopt low carbon technologies. Investment in bioenergy demonstration sites will help show how to cut emissions. Food companies also need incentives for the commercial adoption of low carbon solutions. In Ireland, the long-anticipated Renewable Heat Incentive (RHI) scheme should encourage food manufacturers to generate energy from their bio-degradable processing residues. 

Clearfleau’s industrial bio-digestion plants convert food processing residues into bioenergy and have been installed on a range of production sites including cheese factories and whisky distilleries.  They offer energy-efficiency and wider environmental benefits:  

§  Bio-Energy - cutting fossil fuel use, helping meet energy reduction targets 

§  Emissions - replacing fossil fuel with bio-energy, cutting carbon emissions

§  Water use - cleansed water fit for river discharge, suited for re-use on site

§  Land fertility - residual bio-solids can provide nutrients for growing crops  

§  Efficiency - extracting energy from residues improves overall resource use.

AD offers a flexible energy supply - heat or power generated at source. There are three outputs: biogas (clean energy), cleansed water (for river discharge after aerobic polishing), and residual biosolids for soil fertility (e.g. to grow grass to feed cows producing milk to supply the creamery). 

Dairy Case Study:

One of Europe’s largest cheese creameries, First Milk’s Aspatria site in Cumbria, converts its energy-rich processing residues from cheese production into renewable energy. The biogas is upgraded to biomethane to supply the local gas grid.

This plant, built and operated by Clearfleau, converts over 1,000m3 per day of cheese whey into biogas with a thermal value of 5 MWh. The largest on-site AD plant in Europe’s dairy processing sector, it is the first creamery to produce biomethane generated entirely from cheese residues. The biomethane supplies the creamery’s boilers, as well as local households and businesses, and cleansed water is discharged to the nearby river.

Thanks to this sustainable solution for its cheese-making residues, the creamery has reduced its fossil fuel use by over 25%. This approach can be replicated across Europe’s dairy sector, including in Ireland, supported by the new incentives for bio-energy recently announced by the Irish Government, which will be available from 2018 onwards.

A Scalable Solution

Managing resources through on-site AD can also be viable on smaller specialist dairy sites. We have developed a modular design that will make digestion more affordable on smaller sites, targeting a comparable return on investment (ROI) to larger projects.  

Converting liquid residues into biogas in a compact, closed loop system (all feedstocks are pumped into the digester) designed to fit on a confined site is more cost-effective than aerobic treatment, which consumes energy and has a lower return on investment.

Industrial sites that have installed AD plants are saving money and cutting carbon emissions. Bioenergy will contribute to decarbonised manufacturing in a more resource efficient economy.