Life cycle assessment and carbon footprint increase transparency Part 3.

In the spring of 2020, we conducted a study to map the environmental impacts of alternative animal by-product and raw material treatment methods. Our goal in the Honkajoki Group is to strive to keep nutrients in circulation and thus, for our part, to protect the Earth’s biodiversity. By one’s own actions, man can influence whether the soil acts as a carbon sink or merely as a source of emissions. Nutrient cycling is one of the ecosystem services produced by nature that preserves and promotes the well-being of human communities. Humanity uses about 72% of the earth’s land that is not under permanent ice cover. At the same time, agriculture, the forest industry and other land uses are responsible for about a quarter of all emissions. Key practices against soil depletion include ending waste of resources, reducing food waste and adopting environmentally friendly technologies.

When we started the work to map the emissions, the first step was to calculate the Honkajoki Group’s emissions. Secondly, we commissioned carbon footprint calculations for our two best-selling products. Third, we were interested in alternative treatment methods for what is found on the market for an animal by-product. This article explains the results of this study.

We come across on regular basis with the question which is the best way to process animal by-products. There are plenty opinions on the matter, and we wanted to study in more depth biogas option as well as landfilling which is unfortunately very common in emerging markets where we want to make a difference with Honkajoki® concept.

We did a scenario calculation for a factory that receives 80.000t of raw materials per year in China. The first option was to render the raw materials and produce added value products for the market as in fat and feed. Second option was to process the raw material in a biogas plant and the third option was to direct the raw materials to a landfill.

We will also take a look at the benefits which arise from the use of circulated nutrients. Protein meal produced by Honkajoki can be used to replace for example soya etc plant-based protein in animal feeds.




We included soft residues of slaughterhouse by-products, bones and feather were included in the assessment. Mix of porcine and poultry slaughterhouse by-products was used in the estimation of biogas production and landfill disposal effects. Calculations of protein meal were made by Honkajoki Group and they were based on existed data of protein production in Finland and technical data of potential production machines. Data related to biogas production and landfill was mainly based on research publications. Some data for biogas calculation is based on biogas plant that uses residual biomass from Honkajoki plants in Finland. In landfill processes modelling no particular location were taken into account.


Alternative methods

Anaerobic digestion is one possibility for slaughterhouse by-product treatment. The process produces biogas that can be utilised in energy and biofuel production. The amount of generated biogas depends on biomass quality and type of anaerobic process. Benefits of this treatment method are generated when biogas substitutes the use of fossil fuels and when the nutrients in the resulting left-over side streams are used for substituting the use of mineral fertilizers. For this reason, the environmental contribution of mineral phosphorus and nitrogen production as well as energy production from fossil fuels is studied.

Landfill disposal is one of ways of biomass treatment. It includes biomass transportation and its placing at polygon. It takes less than 50 years for biomass total biodegradation at the polygon. Methane and carbon dioxide gases generated in the process release to the atmosphere if landfill gas collection is not organized. It was assumed in the calculation, that landfill gases are not collected.



Life cycle stages A1-D on product stage

Life cycle assessment scope was cradle-to-gate and represents only the product stage.

Studied system covers the following life cycle stages:

• A1- Raw material production

• A2- Raw material transportation to manufacturing site

• A3- Manufacturing

• D-Benefits

A1: The environmental impacts of raw material supply (A1) include emissions generated when raw materials are taken from nature, transported to industrial units for processing and processed, along with waste handling from the various production processes.

A2: The considered transportation impacts (A2) include exhaust emissions resulting from the transport of all raw and ancillary materials from suppliers to production plant as well as the environmental impacts of production of the used diesel. The manufacturing, maintenance and disposal of the vehicles as well as tyre and road wear during transportation have also been included.

A3: The environmental impacts considered for the production stage (A3) cover the manufacturing of the ancillary materials (packaging materials, disinfection chemicals) and fuels used by machines, as well as handling of waste formed in the production processes at the production plant. The environmental impacts of this stage were calculated on the basis of production plant data.

D: Benefits (D) represent emissions that generated from materials recycling and new products manufacturing from secondary materials (slaughterhouse by-products). In other circumstances secondary materials would be disposed and primary raw materials would be used. Benefits come from primary materials by replacing secondary materials. 



Production specific data was collected directly from manufacturer’s production plant. The data represents the production of the studied product at the plant from the materials transported to the facility and represents 1-year average. The data was examined prudently, and clarifications were requested from factory representatives. The data was cross-checked between the plants and the mass balance was also verified.

All gathered data was used without excluding categories in advance following the system boundaries set in earlier chapters. Biogas production and landfill related data are based mainly on research publications, with some additional data received from Honkajoki Oy. The data represents typical actual technologies and methods used in this field at present. The data was examined carefully and in uncertain situations checked from several literature sources. All known inputs and outputs were taken into account in the assessment. In the quantification process the information was collected as comprehensively as possible for the included modules.



Protein meal and fat production have the lowest product stage (A1-A3) emissions. Anaerobic biogas production emissions are almost twice higher than what is observed for protein and fat production. Landfilling is not surprisingly the most environment strenuous method of biomass treatment.

Benefits generated beyond the system boundary may vary depending on modelled scenario and the products chosen for comparison. For protein and fat production the benefits are at the highest when it is assumed that Honkajoki products are used to substitute of soy in final products. When fishmeal is used to subtitude soy, the benefits decrease almost three times.

In anaerobic digestion calculation, it is important to consider which products biogas will replace. The role of nutrient circulation seems to be small. If biogas replaces fossil fuels in heat and electricity production the benefits are higher. If only electricity is utilized, the benefits decrease respectively.



We sometimes come across with the argument that biogas would, in principle, be the best solution for handling raw material of animal origin. However, the study well reveals the relationship between rendering and biogas. The carbon footprint of biogas production is almost double that of rendering when the same amount of raw material of animal origin is processed. The biggest benefits of biogas come from replacing fossil fuels, such as coal, as a source of heat and electricity and it is a valid choice for biomasses which cannot be upcycled to added value products. When assessing the overall impacts of different treatment methods, it is also important to consider where the end products from the process are used and what they may replace in order to have a holistic view of the impacts. Animal protein and fat are commonly used either as a feed material or as a biofuel, i.e. they are for example substituting soy and fossil oil. Soy production has a massive impact on the environment, which should be replaced by alternative solutions.

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