The UK produces around 350,000 tonnes of meat and bone meal (MBM) each year. In Europe, it has proven to be a sustainably developed way of farming, and it’s also being used increasingly by biomass power stations as a source of renewable energy.

MBM arises from process residues provided by the agricultural and meat production industries. Unfortunately around 30% of an animal’s live weight ends up as waste that’s unsuitable for human consumption; it’s made into either meat meal (MM), bone meal (BM) or MBM.

Recycling back to agricultural land

In the past, MBM was widely used as a bovine feed on farms; however, following the Bovine Spongiform Encephalopathy (BSE) crisis, (commonly known as mad cow disease) in 1999, its use has shifted. Now, where there is potential of BSE contaminated residues, MBM must be safely disposed of or transformed. Across Europe, MBM tends to be used in feed for household pets to improve the protein content.

Alternatively agriculturalists have found BM to be a useful organic fertiliser because of the significant levels of nitrogen, calcium, and phosphorus it contains. While it is an important source of nutrients when recycling back to agricultural land, these materials must first be sterilised, and manufacturers must also demonstrate that the intended use was for human consumption, or indeed were fatalities from non-BSE related causes. MBM is progressively being used as a recycled fuel through combustion or anaerobic digestion (AD). Ultimately, however, it is processed with the best value proposition in mind relative to the category of the material in question and, of course, the price.

Using MBM for renewable energy generation

In recent years, biomass power stations have taken the use of MBM further as a source of alternative fuel and renewable energy. MBM has a significant calorific value, and therefore is a useful material for firing or co-firing for energy production and has become a common fuel for renewable energy provision, sitting alongside wood biomass, solid recovered fuel (SRF) and refuse-derived fuel (RDF). Even after combustion and with testing and environmental permissions, residues of ash may still be utilised as a fertiliser, maintaining useful levels of calcium and phosphorus.

There is a word of caution here however, that combustion is not without potential problems, as the material inherently contains high levels of nitrogen and chlorine. The nitrogen converts to nitrogen oxides on combustion and, therefore, requires treatment before emission to air. The chlorine is notoriously a corrosion and slagging promoter, through volatile salts and lowering of ash melting temperatures. In addition, nitrogen is invariably lost from the ash and chlorine may also be concentrated and yield it unsuitable, or have limited use in some agricultural applications. In the UK, MBM is primarily used for energy generation as a fuel in the cement production industry, whose process plants are equipped with systems to control the potential adverse effects from combusting this material.

The testing process

As MBM and other biomass materials continue to help save a significant amount of carbon dioxide emissions each year, their use has consequently attracted a number of renewable energy incentives from the UK Government.

Ken Hepburn, biomass development manager at Knight Energy Services, commented on the importance of MBM testing for those who are reaping its many benefits:

“It’s important for biomass power stations to demonstrate that they are burning a sustainable biomass material. Obtaining this knowledge is necessary for applying for government subsidies around renewable energy.

“At Knight Energy Services, we also test clients’ MBM materials for elements such as chlorine and sulphur because of their corrosion properties and potential emissions to the environment. This is necessary to ensure that the fuel they’re burning is environmentally suitable or properly treated before release to the atmosphere.

“Clients also approach us to determine the quality of their MBM materials by testing for ash content, moisture content, ash composition, ash fusion temperature, and elemental analysis and trace metals.

“Once we’ve received the samples, they will be mixed, ground and homogenised at our dedicated solid fuels laboratories. The samples are then analysed and we provide the results to clients in the form of a detailed report. By establishing the fuel quality, our clients can then assure themselves of compliance (or not) with internal and external criteria.

“We have been testing solid fuels as part of the AHK Group for over 135 years. With the benefit of this experience we are both dedicated and proficient in our field, and are trusted by our customers to deliver a consistent and reliable service. Our ISO 17025 accredited laboratories are suitably equipped to enable us to operate at an efficient and productive level while maintaining a high degree of quality control.”

Looking to the future

The practical benefits of MBM residues are in the number of alternative uses that it provides. Recycling and reuse of the material in some way ensures that every part of the animal biomass is put to use, consistent with a circular economy. This type of biomass production and consumption offers a credible route for the UK to continue to meet its renewable energy targets in the future.

Knight Energy Services offer full-scale testing and analysis of agricultural materials and animal biomass at our ISO 17025 accredited laboratories. Visit our website to find out how we can help you.

Published: 21st October 2020