Category Archives: Food System Model

Assessing circular food systems: Fish oil substitute produced from food waste

Imagine that you buy three bags of food at the grocery store and throw away one of them before you get home. Seems crazy right? But the truth is that about one-third of the food produced today is wasted, meaning that a considerable amount of food is produced in vain. Overproduction, cosmetic standards, inefficient logistics and overconsumption are some examples that cause wastage of still edible food along the food supply chain. This waste leads to considerable environmental impact, economic losses and critical social consequences.

Recovering valuable resources and circulating them back to the food supply chain instead of wasting them could lead to important benefits compared to the current system. In fact, using already available resources and reduce waste is considered essential to maintain future food security, enable the transition towards a circular economy and support sustainable development. So, how should we use these resources then? One solution could be to produce a fish oil substitute via microalgae using food waste as feedstock.

Food from waste

Today, aquaculture is one of the fastest growing food-producing sectors globally, and each year we produce about 1-million-ton fish oil rich in the essential fatty acid DHA (found in Omega-3). Since Omega-3 must be obtained through diet, it is often added to food and feed production (often in the form of fish oil) to enhance nutrition levels in dairy, meat and fish consumed by humans. In the beginning, aquaculture was considered a solution to decreased biodiversity and diminished ecosystems, as a result of overfishing. However, the fish oil industry required to support traditional aquaculture is highly dependent on fossil energy and marine raw materials, which leads to depletion of natural resources and ecosystems as the global demand for fish increases. Instead of solving the problem of overfishing, aquaculture has created new ones. At the same time, about 1.3 billion tons of food is wasted globally every year.

In aquatic ecosystems, the essential fatty acid DHA is produced by microalgae and accumulated in fish via the food web. Therefore, one promising solution is to gain DHA directly from microalgae. Research shows that heterotrophic microalgae can be cultivated in bioreactors using volatile fatty acids (VFA) derived from food waste as primary carbon feedstock.

Feeding algae VFA to produce an algae oil rich in DHA could provide multiple benefits in comparison to traditional fish oil, especially since biogas can still be produced alongside. This means that we can produce multiple valuable products from food waste, which would further reduce pressure on natural resources. Producing a fish oil substitute using already available recourses could also support circular food systems and improve global food security. However, assessing and evaluating the environmental implications of new technologies is crucial to ensure that the suggested solutions also support future sustainability.

Environmental impact and loss of biodiversity

This study aimed to evaluate the future potential of DHA produced from algae with a primary carbon feedstock from food waste, by assessing and comparing its environmental impact to that of DHA from Peruvian anchovy oil. The studied systems were modelled as two parallel scenarios to assess large-scale production of DHA: a conceptual Algae scenario and a conventional Fish scenario.

Simplified scenario illustration, created using

A life cycle assessment (LCA) approach was used to obtain a holistic quantification of the impact caused by the Algae scenario and the Fish scenario, from the extraction of raw materials via production to finished product. Using LCA indicators at both midpoint and endpoint along the cause-effect chain can provide a vital dimension of total impact to policymakers, the research community and industry. Moreover, including endpoint impact such as damage to ecosystem quality is especially important in systems dependent on biotic resources, such as fish oil production. By definition, biodiversity refers to the variability among all living organisms and maintaining biodiversity is essential for life on Earth. As natural systems and species are dependent on each other, damaged ecosystem quality or loss of even a small number of species could lead to irreversible consequences. Therefore, the endpoint indicator Ecosystem damage was included in this study as a complement to the midpoint indicators global warming, acidification, eutrophication, and land use.

Algae oil VS Fish oil

The main findings were that DHA produced from the Algae scenario inferred lower impact with respect to global warming, acidification and land use compared to the Fish scenario. Moreover, algae oil also resulted in lower climate impact when compared to rapeseed oil and linseed oil, two common plant-based Omega-3 sources. And even though established LCA methods cannot fully account for the total impact on biodiversity, the result showed that DHA from algae inferred lower Ecosystem damage compared to fish oil even when future energy development, improved efficiency, increased energy demand and impact on biotic resources were simulated.

This study showed that DHA produced by microalgae using VFA from food waste can reduce dependency on marine raw materials while also enabling increased resource efficiency by recovering nutrients in food waste for value addition. By using agricultural and food industry by-products to produce DHA, overfishing could be counteracted which in turn would benefit maintained ecosystem quality. Algae oil holds a promising potential for increased sustainability within aquaculture, provided that continued development and optimization of this emerging technology are enabled through active decision-making and purposeful investments. So, recovering valuable fatty acids from food waste and reusing them to produce a fish oil substitute could indeed be a way to increase circularity and sustainability both within aquaculture and the future food system.

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Want to learn more about this project? Then we invite you to read the full article:

L. Bartek, I. Strid, K. Henryson, S. Junne, S. Rasi, M. Eriksson (2021). Life cycle assessment of fish oil substitute produced by microalgae using food waste. Sustainable Production and Consumption, vol 27, pp 2002-2021. doi:

Assessing the Circularity of Nutrient Flows in the Okanagan Bioregion, BC Canada

Recent years have seen a steep rise in the interest in ‘nutrient circularity’, ‘closing the nutrient loop’, ‘circular nutrient solutions’, and ‘circular nutrient economy’. As part of a broader food system design project in the Okanagan Bioregion, BC Canada, we took the opportunity to help stakeholders in the bioregion better understand current levels of nutrient circularity and how it could be improved.

The notion of nutrient circularity seems to generally encompass the reduction of nutrient losses – during agricultural production, processing, distribution, and consumption – along with comprehensive recovery of nutrients from organic residuals, for reuse in agricultural production. Nutrient circularity has been defined, for example, with a focus on waste management – as the fraction of nutrients in waste streams that are recycled to agricultural production. This circularity indicator could be referred to as ‘output circularity’. Nutrient circularity has also been defined with a focus on agricultural biomass production – as the fraction of total nutrient inputs that are supplied from waste streams. This circularity indicator could be referred to as ‘input circularity’.

Due to the trade of feed and food, nutrient inputs to crop production in one place may make their way into organic residuals in another place. When assessing the level of nutrient circularity for a bioregion like the Okanagan, simply comparing nutrient need and availability may thus give a distorted picture.

To account for the effect of feed and food trade on nutrient circularity in the Okanagan, our analysis went beyond nutrient need and nutrient availability in the bioregion exclusively. Insofar as nutrient flows relate to food consumption (much of which is imported) and production (much of which is exported) in the Okanagan bioregion, the analysis also included nutrient need and nutrient availability outside the bioregion. This approach enabled a separate discussion of four kinds of nutrient circularity – internal and external input and output circularity – as well as how they relate to one another and to system openness.

Distinction of four types of nutrient circularity – internal and external input and output circularity.

We assessed nutrient circularity separately for nitrogen (N), phosphorus (P) and potassium (K) – for the baseline year 2016 and four scenarios that explore various possible food system futures in terms of the extent of cultivated land, the structure of the food system, and dietary preferences.

List of scenarios considered in addition to the 2016 baseline.

Our analysis revealed that nutrients flow from the periphery of the bioregion towards the center – where population and livestock densities are highest – and from outside the bioregion into the bioregion. For N and P, feed and food trade were found to increase the nutrient availability compared to nutrient need in in the bioregion as a whole by about 50 percent. This comes at the cost of reducing nutrient availability elsewhere. This pattern of nutrient accumulation in the Okanagan can be expected to be more pronounced in 2050 and also apply to K. This is due to the projected population increase and the possibility for increased local livestock production and thus more feed imports.

System openness for the 2016 baseline. Spatial variation across the Okanagan, and for the Okanagan as a whole (INT = internal, EXT = external).

With current organic residual management practices and infrastructure, nutrients recovered from organic residuals are insufficient to meet crop nutrient needs in the bioregion. If nutrient recovery efficiency was increased from current levels to 70 percent – which reflects a conservative estimate of the recovery rates that full-scale recovery technologies can be realistically expected to achieve in the long run – there would be a surplus for N and P in the bioregion but still a deficit for K. If livestock production and feed imports were to be increased in the future, there would also be a surplus for K.

At first sight, the high nutrient availability compared to nutrient need in the bioregion may suggest that comprehensive nutrient recovery may not be needed in the Okanagan. But the nutrient increased nutrient availability in organic residuals is due to system openness associated with feed and food trade. In other words, the increased nutrient self-reliance internal to the bioregion comes at the expense of a reduced nutrient self-reliance external to the bioregion. Our analysis quantified the extent to which different food system scenarios aggravate or mitigate this pattern.

Provided that the goal of nutrient management is to maximize nutrient circularity, across all scenarios, it will be necessary to re-distribute nutrients both within and across the spatial boundaries of the Okanagan. This would help to at least partially compensate for nutrient depletion external to the bioregion in the places from where feed and food are imported. Our analysis estimated the tons of NPK that would need to be moved outside the bioregion to compensate for system openness. Alternatively, if nutrients are not moved from areas where they are accumulating, they are likely to have adverse environmental impacts and aggravate anticipated future nutrient scarcity.

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Find out more about the Bioregion Food System Project here and read more about nutrient management in the Okanagan in our technical research report. A suite of scientific papers are currently under review and will be released later this year.

The European Union’s hunger for soybean

In a recent paper published in Nature Food we show that halted soybean feed imports into the EU would favour ruminant animals such as cows and sheep over pigs and poultry. We also show that total production of animal-source foods in the EU would have to reduce if animal feed production is not to encroach on land currently used to produce food. Increased uptake of plant foods in EU diets is required maintain supply of nutrients.

The fires that raged in the Amazon during the 2019 fire season was unprecedented in number since records began in 2013. Although the drivers are numerous a paper in Global Change Biology has attributed the increase in fire count mainly to increased deforestation rates. When forests are cleared the vegetation is left to dry before it is burned off to make way for agriculture.

Agricultural expansion where natural vegetation is cleared and replaced with fields and pastures is one of the major threats to biodiversity and releases large quantities of greenhouse gases into the atmosphere. One of the recognised drivers of agricultural expansions into rainforests and other biomes in South America is demand for soybeans. The majority of soybeans produced in the region are destined for export markets. While domestic legal frameworks are important for forest protection, international trade has been shown to be an important driver of tropical deforestation and macroeconomic factors can often outweigh domestic regulations. Demand-side measures that reduce demand for soybean are therefore important to avoid further loss of forests.

Most of the soybean produced globally is “crushed” to separate the vegetable oil from the protein-rich meal. Each kg of soybean generates around 0.2 kg vegetable oil and 0.8 kg protein meal. Most of the revenue from the soybean crush is generated by selling the protein meal which is almost exclusively used to feed animals. This means that it is increased use of soybean meal, and ultimately demand for animal products, that primarily drives up soybean demand which leads to clearing of new areas in order to increase production.

Out of the total amount of soybean (beans, meal and oil) exported from South America around one-fifth is imported into the EU, where the vast majority is used to feed animals producing meat, milk and eggs. For example around 0.8 kg soybean is used to produce the average kg of EU pork, much more than needed for a kg of soy meat or tofu. If rough feeds (e.g. grass and silages) are excluded almost one-third of all protein fed to EU livestock comes from imported soybean. Demand for animal-source food within the EU thereby drives global soybean demand and tropical deforestation in South America.

Soybean is in itself an excellent crop with among the highest yields of protein per hectare, and being a legume, it fixates nitrogen from the air which reduces the need to apply nitrogen in the form of mineral fertilizers. Soybean is also one of few crops that is on par with animal-source foods when it comes to amino acid profile. The huge demand from the world’s livestock industry for cheap soybean does however make it hard to implement sustainable production.

When fed to animals, the majority of nutrients and energy present in the soybean are lost as heat or manure and only a small fraction is in the end retained in meat, milk and eggs that we eat. Redirecting the use of soybean from feed to eating it directly could therefore reduce the demand considerably. This would reduce pressure to deforest new areas and may also make it easier to implement more sustainable soybean production practices.

In a recent paper published in Nature Food we assess how dependant the EU livestock sector is on soybean imports by estimating how much meat, milk and eggs that would be possible to produce without soybean imports, given that use of EU cropland for animal feed production does not increase, which is important to avoid pushing production of food crops outside EU borders with potential negative environmental effects. We found that, depending on scenario for how to use EU cropland, 18-25% reduced animal-source food production in terms of edible fat and protein would be needed to completely eliminate soybean feed imports. Mainly it was the production of pork and chicken that was reduced, while beef, milk and eggs was less affected in the scenarios. To compensate this loss of nutrition to EU diets only between 17 and 22% of soybean that is currently imported to feed livestock would be needed to produce soy meat, tofu or other products for direct human consumption, thus considerably reducing the EU’s demand for land in deforestation-prone regions. Alternatively some land currently used to produce feed in the EU could be used to produce plant-source foods (resulting in the strongest reduction of animal-source foods presented above). In that case it would be possible to maintain supply of fat and protein to EU diets even without soybean imports.

The potentials for reduced cropland demand in South America were found to be large, but results also showed a risk of increasing cropland demand in South-East Asia, which is also a region where large scale deforestation occurs. Reduced use of soybean meal for animal feed results in less soybean oil being produced and if global demand for vegetable oils remain unchanged, this oil would need to be replaced by other vegetable oils. The most likely alternative today is palm oil. In absolute terms, the increased demand for cropland in South-East Asia was small compared to reduced demand in South America, but it is nevertheless an important potential trade-off that need to be considered. In one of the scenarios we explored the potential to increase rapeseed oil production within the EU to avoid this trade-off. Such a scenario would avoid increased palm oil demand, but instead rely on continued soybean imports to compensate for reduced consumption of meat. Which scenario is preferable will depend on how future global demand for different agricultural products develop. If for example transition from fossil fuels is achieved through the use of vegetable oil fuels a scenario with increased vegetable oil production in the EU is likely a good candidate.

In summary, the results from the new study show that there is a lot to gain by redirecting feeds of high food value, such as soybean, towards direct human consumption. To achieve these benefits without risking burden shifting it is however crucial that policies are developed with a holistic food systems approach and target soybean imports, dietary patterns, and livestock and crop production in conjunction.

Karlsson, J.O., Parodi, A., van Zanten, H.H.E., Hansson, P-A., Röös, E. (2020). Halting European Union soybean feed imports favours ruminants over pigs and poultry. Nature Food.

Soybean use for plant-based products shown in the figure was calculated based on data from the following sources:

Karlsson Potter, H., Lundmark, L. & Röös, E. (2020). Environmental impact of plant-based foods – data collection for the development of a consumer guide for plant based foods. Swedish University of Agricultural Sciences, NL Faculty/ Department of Energy and Technology.

Ercin, A. E., Aldaya, M. M., & Hoekstra, A. Y. (2012). The water footprint of soy milk and soy burger and equivalent animal products. Ecological Indicators, 18, 392-402.

Mejia, A., Harwatt, H., Jaceldo-Siegl, K., Sranacharoenpong, K., Soret, S., & Sabaté, J. (2018). Greenhouse Gas Emissions Generated by Tofu Production: A Case Study. Journal of Hunger & Environmental Nutrition, 13(1), 131-142.

Cai, T. D., Chang, K. C., Shih, M. C., Hou, H. J., & Ji, M. (1997). Comparison of bench and production scale methods for making soymilk and tofu from 13 soybean varieties. Food Research International, 30(9), 659-668.

Ecoinvent v3.6 – Products: Tofu production (GLO) and Soybean beverage production (GLO)