High water, high waste - How distilleries can displace the cost of waste liquid

Posted by Clare Burns on 01-Sep-2015 09:00:00

Using a biogas project to generate biogas fuel from your distillery’s organic liquid waste will result in major energy savings, reduced greenhouse gas emissions, reduced effluent disposal charges and lower water consumption.

With steadily increasing water supply costs, compounded by rising charges for effluent disposal, the effective management of a distillery’s inherently high water consumption and high effluent production is a major challenge for an energy manager targeting energy efficiency and environmental improvements.

Under the new Mogden formula, effluent disposal charges are now calculated using the concentration of dissolved organic pollutants – the chemical oxygen demand (COD) – and the suspended solids in a liquid waste.

High energy, high costs, high emissions

Distillery processes, including traditional effluent disposal by evaporation, incineration and wastewater treatment, require very high consumption of electricity and heat energy. If using conventional grid energy supplies, this means very high costs and very high greenhouse gas emissions.

Controlling water consumption and effluent generation is one way of reducing energy and disposal costs – but not the only way.

Turning liquid waste into renewable energy

Creating a sustainable source of energy from distillation by-products that have a high organic content, such as post-distillation liquor and evaporator condensate, will save energy and improve a distillery’s carbon footprint.

The biodegradation of organic matter in a process known as anaerobic digestion (AD) produces methane-rich biogas. The main use of biogas is as a combustion fuel for a Combined Heat and Power (CHP) unit, which generates on-site renewable electrical power and heat energy. Alternatively, excess biogas can be treated and upgraded to biomethane, which may be injected into the national gas grid or used as a transport fuel.

This is worth considering because, typically, every kg of COD in effluent may produce 0.245m3 of biogas (with a methane content of 80%), which generates 1 kWe and 2.4 kWth at a conversion efficiency of 40%. See more in Future Energy Opportunities: A Guide for Distillers (p23) published by The Scottish Whisky Association.

Energy savings, reduced emissions

A biogas project using AD and CHP technologies not only provides major energy savings by displacing the use of fossil fuels, but will also reduce a distillery’s greenhouse gas emissions. The methane in biogas is completely consumed by the CHP combustion process, and there is a zero increase in CO2 emissions in the CHP exhaust gases, because the amount of CO2 is the same as that originally absorbed during photosynthesis of the organic waste matter.

In addition, distilleries that produce biogas and use it to generate renewable energy can become more energy self-sufficient, with less reliance on energy from the national grid.

Reduced waste management charges

The latest advancements in AD technology are further improving the final quality of effluents.

AD pre-digestion produces an even greater conversion of organic compounds, which lowers the liquid waste’s COD and consequently reduces effluent disposal charges. Post AD treatment removes substances, such as nitrates and phosphates, to produce cleansed water for reuse on-site typically as a process wash down or for steam generation – with reports of up to 40% of the total volume being recycled.

Cost savings

By installing a biogas project, the most significant saving is a reduction in energy costs. But, in addition, using biogas generated from liquid waste will also:

  • Reduce the amount of effluent and its associated disposal charges
  • Reduce water consumption costs if combined with water recycling
  • Save on transport costs and landfill taxes by reducing the disposal of unusable solid wastes.

Not only that, when considering a biogas project it is important to appreciate the additional financial benefits available through the support of the Feed-In Tariff and Renewable Heat Incentive schemes.

For distilleries, the water that becomes part of the end product is the most important ingredient. But with the capability to produce methane-rich biogas to generate renewable energy, waste liquid is a valuable by-product that shouldn’t be ignored.

You can displace the cost of your liquid waste by:

  1. Controlling your distillery’s water consumption and effluent generation
  2. Creating the sustainable source of energy - biogas- from your distillery’s by-products
  3. Installing a biogas AD/CHP project to generate renewable energy
  4. Using this renewable energy to save on energy costs and reduce effluent disposal costs

Find out how to displace the cost of your waste liquid by downloading our free eGuide: What to Consider When Planning a Biogas Project (F&D)

What to Consider When Planning a Biogas Project (F&D)

Topics: Food and Drink Manufacturing

Clare Burns

Clare Burns is a technical marketer with many years’ experience in the energy arena, as well as in fashion, telecoms and education. Fluent in 3 languages, Clare has worked across Europe. She currently works for ENER-G, a UK manufacturer of carbon reducing, energy efficient products exporting its cogeneration technology across the globe.