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Why create energy from production residues? (18 February 2016)

Posted: 2016-11-21 17:20:53

Why create energy from production residues? (18 February 2016)

Factory and Energy managers are starting to realise that residues from food and drink processing as well as from biofuel or pharmaceutical production are a potential source of energy instead of an unwelcome expense.  Companies like Nestlé, Diageo and First Milk have shown how on-site Anaerobic Digestion can reduce energy costs.  Richard Gueterbock, Director of Clearfleau, a leading British provider of AD technology, explains why the opportunity to convert residues into energy is an investment option that manufacturers should evaluate now, while financial incentives are still available. 

 

There is a growing interest in how national sustainability targets and promotion of the circular economy will impact on the behaviour of businesses across the UK.  One key opportunity is the development of smaller-scale, on-site energy generation on manufacturing sites.  

Decentralised energy generation, by adding value to unwanted by-products, can offer an attractive investment return in under 5 years, based on cost savings and FIT and RHI incentive payments.  Unlike more weather-dependant renewables such as wind or solar, Anaerobic Digestion (AD) of process residues can supply base load energy to food and drink processors at the point of use.  Nestlé, Diageo and First Milk are three companies generating energy from very different production residues.  Here’s how each of them is using anaerobic digestion to reduce costs and their carbon footprint.

First Milk (Lake District Biogas)

Clearfleau’s technology facilitates the effective processing of fatty production residues, as in the case of First Milk’s creamery in Cumbria, a leading cheddar cheese production site.

First Milk set up Lake District Biogas to build and operate the first on-site AD plant in Europe to supply up-graded bio-methane to the gas grid, based entirely on cheese production residues. 

 

The plant is a major boost for the creamery and for the local farms that supply the milk, as it cuts energy costs and addresses inefficiencies in the disposal of unwanted whey permeate and other production residues, reducing the sites energy and disposal costs.  Most of the biogas generated at the site in Cumbria is upgraded in a membrane-based system to remove impurities prior to injection to the gas grid. 

It is possible that other dairy and distillery sites will seek to replicate this approach, if the Government does not remove the incentive structure too quickly. Wyke Farms is Somerset also has an AD plant that puts gas into the grid.  This is a different system based on a wider range of inputs including local food waste and crop feedstocks.  Digestion is also well suited to managing liquid production residues, as in the case of Diageo’s whisky distilleries…

Diageo

Diageo is a global brand and its whisky is produced in the beautiful Scottish Highlands, where the heritage of whisky production is updated, as Diageo converts its distilleries to renewable energy.  The AD plant at Diageo’s distillery at Dailuaine became operational in 2013 and was the first distillery site to use on-site AD technology to handle higher-strength pot ale, alongside other more dilute distillery liquid co-products. 

In August 2015 a second bio-energy plant was installed, at Diageo’s Glendullan distillery at Dufftown where it was designed to handle co-products from several nearby distilleries.  This second plant generates over 2 million m3 of biogas, delivering 8,000 MW hours of thermal energy from an on-site biogas boiler. 

By turning 1,000m3 of co-products per day into 1MW hour of heat, the site saves over 1,000 tonnes of carbon each year.  It also cuts over 15 truck journeys daily, with a new pipeline supplying the AD plant from several nearby distilleries.  Further carbon savings are derived from the change from conventional aerobic to the more energy-efficient anaerobic treatment. 

Designs are being developed for further plants across the Highlands of Scotland, where on-site AD can bring great benefits to smaller, more remote distilleries as well as in the food processing sector across the UK.  

Nestlé

Nestlé, one of the world’s leading food and nutrition companies, is committed to sustainable manufacturing.  In 2014 Nestlé installed an on-site AD plant at its confectionery factory at Fawdon, Newcastle where it produces brands including Toffee Crisp, Fruit Pastilles and Rolos. 

Previously, liquid effluents were discharged to sewer and the site’s solid production residues were transported to local farms as pig feed.  By harnessing the energy potential of these discarded materials, Nestlé is now generating significant revenue from residue disposal, energy savings and incentive payments. 

 

Nestlé’s new AD plant handles around 1,200 tonnes of solid production residues, by-product and residual ingredients each year.  The plant converts this, plus over 200,000 litres per day of process effluent, into renewable energy through the generation of biogas.  This gas produces up to 200kW hours of electricity, equating to about 10% of the factory's power requirements.  The process generates at least 10% more biogas than other high-rate digestion systems.

For Nestlé, what was previously a processing overhead is now a valuable financial and environmental asset.  Nestlé is looking at the potential benefits of on-site renewables on its other manufacturing sites. 

On-site AD processes are designed to be installed on production sites and to digest a range of liquid residues, including those with a higher fat content.  This is how the process works...

How Anaerobic Digestion works

Feedstock is pumped to balance tanks and then to the digester tank. The solids management system breaks the link between hydraulic retention time in the digester and that for the degradable solids, which are retained in the tank, minimising digester size and maximising gas output.  The solids separation unit returns the solids to the reactor tank, prior to passing on

cleansed effluent for further polishing.   Our liquid digestion process can accommodate fatty materials and will reduce the chemical oxygen demand (COD) in the feedstock by over 95% to

produce biogas with a methane concentration of at least 55%.   Residual digestate can be discharged to sewer, or to watercourse with limited post-digestion aerobic treatment. 

Biogas produced in the digestion process is stored in the space above the reactor in a flexible bio-dome.  The gas can be fed to a Combined Heat and Power (CHP) unit, to produce power for use on site, combustion in a dedicated biogas boiler or upgrading to bio-methane for injection to the gas grid.   By applying Anaerobic Digestion, food and drink processors, as well as biofuel and pharmaceutical companies can replace fossil fuel purchases and reduce their carbon footprint to create a truly sustainable manufacturing process.

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For further information and more high/low res images and diagrams please contact: Gaye Spencer, GSPR Environmental

Tel:                  01635 569992

Email:              gaye.spencer@gspr.uk

 

Notes to editors

Clearfleau’s (www.clearfleau.com) award-winning innovative design sets it apart from other high-rate digestion technologies.   This anaerobic digestion process treats fatty materials in a system designed for liquid residues, diverting them away from sewer discharge to produce biogas for conversion into green energy, with digestate nutrients used for crop fertilisation.