Circular bioeconomy in life cycle assessment - addressing multifunctionality of agriculture

Due to many serious environmental issues, the production, consumption and disposal of biological resources must shift from a linear system towards a circular bioeconomy. Although the circular bioeconomy has the potential to respond to the changes needed in society, the environmental impacts of various practices must be assessed to identify potential challenges, such as land use competition with food production or negative environmental impacts. Agriculture is a particularly important multifunctional system for the circular economy, which, in addition to its primary function of food production, produces a variety of biomasses that can be utilized as raw material. Furthermore, agricultural systems can recycle by-products and wastes from other industries as fertilizers and soil improvers. The established method for calculating environmental impacts is the life cycle assessment (LCA) of a product, which aims to capture all impacts caused throughout the entire life cycle of a product system. An allocation procedure is used to partition the environmental impacts of multifunctional systems producing more than one product among all products, resulting in the environmental impact of a single product. This information on the environmental impacts of individual products is typically compared with the impacts of other similar products and used to support decision making. As the allocation method unavoidably affects the results for an individual product, the principles of the allocation methodology must be justified. This dissertation handles the methodological consideration of the circular bioeconomy in the context of LCA of products from agricultural systems. The objectives of the dissertation are to examine the multifunctionality of agriculture, the different by-products and their recycling, and how the choice of allocation method between products affects the results. Dairy production is used as an example case, since it produces two different foodstuffs as well as various inedible materials, making it an excellent research subject for dealing with multifunctionality. This dissertation consists of three research papers and a synthesis of them. The first paper (I) examines how the multifunctionality of livestock systems has been addressed in previous LCA studies through an extensive systematic review of 232 studies. The methodological treatment of recycling and the effect of the choice of method on the results are investigated in paper II through an LCA of recycled fertilizers. The third paper (III) compares the environmental impacts of beef from dairy and beef cattle, pork, cellular meat and tofu production at the system level instead of the level of individual products, considering all the inedible by-products. The findings of this dissertation demonstrate that, despite attempts to harmonize the LCA method, practices vary between studies and the differences in results due to the choice of method are significant. The relative system-level results also differ significantly from the allocated results for individual products. Hence, allocation should be avoided more often, and comparisons should be made between systems rather than individual products. This would also better reflect the reality, where decision making based on one product inevitably also affects all the other products produced by the system. For example, the environmental impact of milk and beef is usually dealt with separately, even though in reality milk cannot be produced without meat, and decision making on milk alone is not therefore possible. Hence, more system level research is needed.Useiden vakavien ympäristöongelmien vuoksi uusiutuvien luonnonvarojen tuotannon, kulutuksen ja jätteenkäsittelyn on siirryttävä lineaarisesta järjestelmästä kohti kiertobiotaloutta. Vaikka kiertobiotaloudella voidaan vastata ympäristöongelmien vähentämiseksi tarvittaviin yhteiskunnallisiin muutoksiin, eri toimintatapojen ympäristövaikutuksia on kuitenkin arvioitava optimaalisten tulosten saavuttamiseksi. Maatalous on erityisen tärkeä kiertotalouden monitoimijärjestelmä, joka ruuan lisäksi tuottaa monenlaisia biomassoja, joita voidaan hyödyntää raaka-aineena. Lisäksi maatalousjärjestelmissä voidaan kierrättää muiden teollisuudenalojen sivutuotteita ja jätteitä lannoitteina ja maanparannusaineina. Elinkaariarviointi (LCA) on vakiintunut tuotteiden ympäristövaikutusten laskentamenetelmä, jonka tavoitteena on ottaa huomioon kaikki tuotejärjestelmän koko elinkaaren aikana aiheutuvat ympäristövaikutukset. Yksittäisen tuotteen ympäristövaikutusten laskemiseksi tuotejärjestelmän ympäristövaikutukset tulee jakaa kaikkien järjestelmän tuottamien tuotteiden kesken allokointimenettelyllä. Usein yksittäisten tuotteiden ympäristövaikutuksia verrataan muiden vastaavien tuotteiden vaikutuksiin ja vertailujen tuloksia käytetään päätöksenteon tukena. Koska laskennassa käytetty allokointimenetelmä vaikuttaa väistämättä yksittäiselle tuotteelle laskettaviin ympäristövaikutuksiin, tulee käytetyn allokointimenetelmän olla perusteltu. Tässä väitöskirjassa tutkitaan kiertobiotalouden metodologista käsittelyä maataloustuotteiden elinkaariarvioinnissa. Väitöskirjan tavoitteena on tarkastella maatalouden monitoiminnallisuutta, erilaisia sivutuotteita ja niiden kierrätystä sekä sitä, miten tuotteiden välinen allokointimenetelmä vaikuttaa tuloksiin. Esimerkkitapauksena käytetään maidon tuotantoketjua, sillä se tuottaa kahta erilaista elintarviketta sekä erilaisia syötäväksi kelpaamattomia materiaaleja, mikä tekee siitä erinomaisen tutkimuskohteen monitoiminnallisuuden käsittelemiseksi. Väitöskirja koostuu kolmesta tutkimusartikkelista ja niiden yhteenvedosta. Ensimmäisessä tutkimuksessa tarkastellaan laajan 232 tutkimuksen systemaattisen kirjallisuustarkastelun kautta, kuinka maidon ja naudanlihan tuotannon monitoiminnallisuutta on käsitelty aikaisemmissa LCA-tutkimuksissa. Toisessa artikkelissa tutkitaan kierrätyksen metodologista käsittelyä ja menetelmän valinnan vaikutusta tuloksiin kierrätyslannoitteiden elinkaariarvioinnin avulla. Kolmannessa tutkimuksessa verrataan naudanlihan (lypsy- ja lihakarjasta), sianlihan, viljellyn lihan ja tofun tuotannon ympäristövaikutuksia järjestelmätasolla yksittäisten tuotteiden vertailun sijaan, huomioiden myös kaikki syötäväksi kelpaamattomat sivutuotteet. Tämän väitöskirjan tulokset osoittavat, että huolimatta LCA-menetelmän harmonisointiyrityksistä, käytännöt vaihtelevat tutkimusten välillä ja menetelmän valinnasta johtuvat erot tuloksissa ovat merkittäviä. Suhteelliset järjestelmätason tulokset eroavat myös merkittävästi yksittäisille tuotteille allokoiduista tuloksista. Järjestelmätason vertailu kuvastaa myös paremmin todellisuutta, jossa yhteen tuotteeseen perustuva päätöksenteko vaikuttaa väistämättä myös kaikkiin muihin saman järjestelmän tuottamiin tuotteisiin. Esimerkiksi maidon ja lypsykarjasta peräisin olevan naudanlihan ympäristövaikutuksia käsitellään yleensä erillisinä, vaikka todellisuudessa päätöksentekoa ei voida kohdentaa vain yhteen tuotteeseen. Näin ollen lisätutkimusta tarvitaan järjestelmätason vaikutusten arvioimiseksi

Environmental impacts of recycled fertilizers in production of oat (Avena)

Kasvava tarve tuottaa ruokaa vähemmällä materiaalilla ja energialla sekä pienemmillä kasvihuonekaasupäästöillä asettaa kyseenalaiseksi nykyisen neitseellisistä raaka-aineista valmistettavien ja runsaasti energiaa kuluttavien mineraalilannoitteiden käytön. Toisaalta myös erilaisista sivuvirroista ja biomassoista valmistettavia kierrätyslannoitteita tulee kuitenkin useimmiten prosessoida lannoitekäyttöön sopivaksi tai niiden käyttömäärät ovat merkittävän suuria, jolloin osa niiden ympäristöhyödyistä menetetään. Tutkimuksen tavoitteena oli selvittää sekä kierrätyslannoitteiden (ammoniumsulfaatti, biokaasulaitoksen mädätysjäännös ja lihaluujauho) että mineraalilannoitteen elinkaarinen energiankäyttö ja kasvihuonekaasupäästöt kauratonnin tuotannossa elinkaarianalyysin avulla ja vertaillla eri lannoitteilla mahdollisesti saavutettavia ympäristöhyötyjä. Kaikkien kierrätyslannoitteiden havaittiin aiheuttavan mineraalilannoitetta vähemmän kasvihuonekaasupäästöjä ja kuluttavan vähemmän energiaa. Kaikista vähiten kasvihuonekaasupäästöjä aiheutti ammoniumsulfaattilannoitus ja energiatehokkain lannoite oli mädätysjäännös. Maailman ravinnon- ja energiankäytön kasvun sekä ilmastonmuutoksen hillitsemisen ja raaka-aineiden kierrätyksen kannalta tarkasteltuna kierrätyslannoitteet osoittautuivat mineraalilannoitetta tehokkaammiksi lannoitteiksi. Myös maankäytön ja sadontuottokyvyn perusteella kierrätyslannoitteiden havaittiin olevan potentiaalisia mineraalilannoitteiden korvaajia. Lisätutkimukset ovat kuitenkin tarpeen kierrätyslannoitteiden lukuisista raaka-aineista ja jatkuvasti lisääntyvistä prosessointimenetelmistä johtuen.Global growing demand to produce more food with less inputs and energy without causing greenhouse gas emissions challenges the current practice of using mineral fertilizers which are produced from new and partly non-renewable raw materials with considerable amount of energy. On the other hand recycled fertilizers made of different side streams and biomasses also need to be processed before usage or the amount needed per area is so great that the environmental advantages might be lost. The aim of this study was to discover and compare the energy consumption and greenhouse gas emissions of recycled fertilizers (ammonium sulfate, biogas digestate and meat bone meal) and mineral fertilizer in production of oat by using Life Cycle Assessment (LCA). All recycled fertilizers were found to cause less greenhouse gas emissions and consume less energy than mineral fertilizer. The least emissions caused the usage of ammonium sulfate and the best energy efficiency was achieved with biogas digestate fertilization. Considered relative to global increase in food and energy consumption and control of climate change and recycling of raw materials recycled fertilizers proved to be effective compared to mineral fertilizer. Also on the grounds of land use and yield recycled fertilizers turned out to be potential substitute for mineral fertilizers. Further studies are still needed due to large number of raw materials and constantly increasing amount of processing techniques of recycled fertilizers

Carbon footprint and energy use of recycled fertilizers in arable farming

The globally growing demand to produce more food with fewer inputs, less energy, and lower greenhouse gas (GHG) emissions challenges current agricultural practices. Recycled fertilizers made of various side streams and types of biomass have been developed mainly to improve nutrient recycling in food systems. However, the knowledge of the impacts of different recycled fertilizers on GHG emissions and energy use is lacking. There is also a need for developing environmental assessment methods for quantifying the impacts of recycling processes, particularly in terms of choosing reasonable methods for co-product allocation. The aims of this study were to address the above mentioned research gaps by i) assessing energy use and GHG emissions of various recycled fertilizers, ii) comparing the recycled fertilizers with mineral fertilizers, and iii) comparing the impacts of using different co-product allocation methods for the recycled fertilizers. Attributional Life Cycle Assessment (LCA) was used for estimating energy use and GHG emissions of recycled fertilizers, including ammonium sulfate, biogas digestate, and meat and bone meal, using kg of nitrogen in the fertilizers as a functional unit. In addition, the energy use and GHG emissions of oat production when using the recycled and mineral fertilizers were quantified. The data were obtained from field experiments, LCA databases, published literature, and fertilizer companies. The life-cycle energy consumption and GHG emissions of recycled fertilizers were found to be lower than that of mineral fertilizer, but also differences between recycled fertilizer products were notable. The biggest differences between fertilizers occurred in manufacturing and transportation. However, this conclusion is highly sensitive to several decisions, such as data sources and LCA methods used. Handling the raw materials of recycled fertilizers as by-products instead of residues adds burdens from primary production to fertilizers. Also handling the materials as waste increases the impacts due to burdens from the recycling process. Since the raw materials of fertilizers have only little economic value, applying economic allocation results to significantly lower impacts than mass allocation. Consequential LCA studies would be needed to improve the understanding of the wider impacts of recycled fertilizers, e.g. considering the benefits of avoided waste management processes. (C) 2020 Elsevier Ltd. All rights reserved.Peer reviewe

Review and expert survey of allocation methods used in life cycle assessment of milk and beef

Purpose Beef and dairy production systems produce several by-products, such as fertilizers, bioenergy, hides, and pet foods, among which the environmental impacts arising from production should be allocated. The choice of allocation method therefore inevitably affects the results of life cycle assessment (LCA) for milk and beef. The aims of this study were to map out the different allocation methods used in dairy and beef LCA studies and to clarify the rationale for selecting a certain method. Methods A literature review was conducted to identify the different allocation methods used in LCA studies of milk and beef production and the products using beef by-products as a raw material. The justifications for the use of different methods in the studies were also collected. To map out the perspectives of LCA practitioners and further clarify the reasoning behind the use of certain allocation methods, a mixed method survey with quantitative questions and qualitative explanatory fields was sent to the authors included in the literature review. Results and discussion The literature review showed that the most commonly used allocation method between milk and meat was biophysical allocation, which is also the recommended method in LCA guidelines of milk production. Economic allocation was the second most common method, although the rationale for using economic allocation was weak. By-products, such as inedible body parts, were not considered in milk studies and were taken into account in only a small number of beef studies. This might be because most of the studies have cradle-to-farm gate system boundaries. According to the survey, a significantly higher share of LCA practitioners would allocate impacts also to these by-products. Conclusions The allocation is usually done between milk and meat, and other by-products are not taken into account. Since these materials are an unavoidable part of production and there are numerous uses for them, these outputs should be recognized as products and also taken into consideration in LCA studies.Peer reviewe

Holistic environmental assessment of High Nature Value farming systems in Europe

Many life cycle assessment (LCA) studies comparing environmental impacts of different beef production systems are incomplete as they exclude biodiversity impacts and soil carbon stock changes. This study aims to assess the environmental impact of ruminant production on semi-natural grasslands or so-called high nature value (HNV) farms at the European level. We collected data for 24 HNV farms in Europe (in Finland, Estonia and France). The studied farms are extensive beef, sheep and goat production systems. We used LCA to assess the potential environmental impact of HNV farms according to global warming potential (GWP100), eutrophication, fossil fuels and water use, by using the Solagro carbon calculator and OpenLCA software. Results showed that HNV farming systems have the potential to maintain unique biodiversity, act as carbon sinks, reduce greenhouse gas emissions and reduce nutrient losses and water use while producing animal-derived food. There were significant differences between HNV farms among countries in their greenhouse gas emissions at the farm level (tCO2eq ha-1) and N inputs (kg N ha-1). Better regional understanding of the environmental impact performance of HNV farming systems in relation to sustainable ruminant production will be achieved as the undergoing study progresses.Peer reviewe

Soil carbon plays a role in the climate impact of diet and its mitigation: the Finnish case

IntroductionDiet has a significant impact on the consumer’s climate impact, and a radical global change in the food system is necessary. However, the change needs to be interpreted and adapted to local conditions.MethodsTo support national climate policy, we evaluated current Finnish diet and its four alternatives: “current diet”; “meat to half diet”; “meat to a third diet”; “a diet rich in fish and milk”; and “a vegan diet”. We created the FoodMin model to simultaneously address both climate impacts and nutrient uptake and to combine carbon dioxide (CO2) emissions from soil organic matter (SOM) degradation with dietary climate impact assessments. As a well-established assessment method remains lacking, product group-specific estimates for the CO2 emissions of SOM origin were produced in two different ways, based on long-term observational data or by modelling with the Yasso07. We also examined, using three scenarios, how much the achievement of soil carbon (C) balance in Finnish production could affect the climate impact of the diet.Results and DiscussionThe climate impact of the current diet was 6.0 kg CO2 per person per day, and for alternative diets, the change compared with the current diet was −14%, −20%, −31%, and −39% respectively, for “meat to half” (5.2 kg CO2 eq. per person per day), “meat to third” (4.8), “a diet rich in fish and milk” (4.2), and “the vegan diet” (3.7). SOM-derived CO2 emissions from domestic fields accounted for 18% of the climate impact of the current diet and up to 23% of alternative diets. In terms of the soil C-balance scenarios, all actions together could mean a 3–13% reduction in the climate impact of the diet: the more products of animal origin, the more reduction opportunities in the diet. With the change in diet, these measures could reduce the climate impact of diets by 13–41%. The nutritional value of a “diet rich in fish and milk” was the best. The study revealed that SOM-induced CO2 emissions and SOM-related activities play a very important role in the climate impact of the diet and its mitigation; they cannot be ignored in dietary assessments in addition to direct product choices

Extending the product-group-specific approach in nutritional life cycle assessment

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