NaOH (sodium hydroxide or caustic soda) is a by-product of the chlorine-alkali process. As this process is determined by the long-term demand for chlorine, changes in demand for NaOH does not affect the output of NaOH from this process.
An analysis of the NaOH market reveals that long-term changes in demand for NaOH will affect the least essential uses of NaOH, i.e. those uses where NaOH can readily displace sodium carbonate (soda ash). A long-term increase in demand for NaOH will thus be met by an increased use of sodium carbonate for those uses where NaOH is not essential, e.g. in pulp and paper, water treatment, and certain chemical sectors where it is used as a neutralising agent. Likewise, a long-term decrease in demand for NaOH will lead to increased displacement of sodium carbonate.
In the current market situation, where there is a global increase in demand for chlorine, the continuously increasing output of NaOH is adequate to cover the applications where NaOH is essential, and a marginal increase in NaOH demand will therefore not lead to a need to produce NaOH from the alternative process route (the caustification process, where NaOH is produced from lime and soda). If there is a further increase in demand for NaOH for essential applications, without a simultaneous increase in demand for chlorine, the caustification process will again be able to play a role as a marginal production route for NaOH, as has been the case previously.
To model the current long-term market reaction to a decreased demand for NaOH in a life cycle assessment, we thus recommend using the derived decrease in sodium carbonate supply. Sodium carbonate is currently produced from NaCl and CaCO3 in the Solvay process (in Europe), and in addition directly from naturally occurring ores (trona) or brines (USA). The displaced sodium carbonate supply may therefore depend on the location and transport costs. The Solvay process is still the dominating process globally, implying that the output from the naturally occurring sources are not globally competitive, and that a decrease in NaOH demand will primarily affect the Solvay process. Sources for environmental data for the Solvay and the trona mining processes are identified.
The consequential approach to system delimitation in LCA requires that consideration of the technologies and suppliers included are ‘marginal’, i.e. that they are actually affected by a change in demand. Furthermore, coproduct allocation must be avoided by system expansion. Vegetable oils constitute a significant product group included in many LCAs that are intended for use in decision support. This article argues that the vegetable oil market has faced major changes around the turn of the century. The aim of this study is to study the marginal supply of vegetable oil as it has shifted to palm oil and describe the product system of the new supply.
The methods for identification of marginal technologies and suppliers and for avoiding co-product allocation are based on the work of Weidema (2003). The marginal vegetable oil is identified on the basis of agricultural statistics on production volumes and prices. A co-product from palm oil production is palm kernel meal, which is used for fodder purposes where it has two main properties: protein and energy. When carrying out system expansion, these properties are taken into account.
The major vegetable oils are soy oil, palm oil, rapeseed oil and sun oil. These oils are substitutable within the most common applications. Based on market trends, a shift from rapeseed oil to palm oil as the marginal vegetable oil is identified around the year 2000, when palm oil turns out to be the most competitive oil. It is recommended to regard palm oil and its dependent co-product palm kernel oil as the marginal vegetable oil. The analysis of the product system shows that the demand for 1 kg palm oil requires 4.49 kg FFB (oil palm fruit) and the displacement of 0.035 kg soybeans (marginal source of fodder protein) and 0.066 kg barley (marginal source of fodder energy).
The identification of the marginal vegetable oil and the avoidance of co-product allocation by system expansion showed that several commodities may be affected when using the consequential approach. Hence, the product system for vegetable oils is relatively complex compared to traditional LCAs in which average technologies and suppliers are applied and in which co-product allocation is carried out by applying an allocation factor.
This article presents how the marginal vegetable oil can be identified and that co-product allocation between oils and meal can be avoided by system expansion, by considering the energy and protein content in the meal, which displaces a mix of the marginal sources of energy and protein for animal fodder (barley and soy meal, respectively).
The implication of a shift in the marginal vegetable oil is significant. Many LCAs on rapeseed oil have been conducted and are being used as decision support in the bio energy field. Thus, based on consequential LCA methodology, it is argued that these LCAs need to be revised, since they no longer focus on the oil actually affected.
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● I den ene metode opgøres alle miljøpåvirkninger i et land, en region eller endda hele verden, hvorefter de fordeles ud på de enkelte produkter, der er årsagen til miljøpåvirkningerne. Dette kaldes input-output-analyse (eller I/O-analyse i økonom-slang). Det er nemlig på baggrund af en kobling mellem den økonomiske statistik og miljøstatistikken at denne metode overhovedet er mulig. Et stort problem med metoden er det detaljeringsniveau (og omfang) som statistikken har. Typisk er statistikken opgjort per branche (og ikke for alle miljøpåvirkninger), i sjældne tilfælde per virksomhed, men aldrig per produkt. Derfor må man gøre en række mere eller mindre vilkårlige antagelser om den endelige allokering af miljøpåvirkninger per produkt.
● Den anden metode starter nedefra, med at opgøre miljøpåvirkningerne i de enkelte processer i produktets livsforløb, fra råstofudvinding over produktion og brug til bortskaffelse, eller populært sagt: "fra vugge til grav". Derefter lægges miljøpåvirkningerne fra de enkelte processer sammen, således at man får et udtryk for produktets miljøpåvirkning i hele dets livscyklus. Metoden kaldes derfor livscyklusvurdering. Et problem med denne metode er, at man ofte ikke har kendskab til alle processer i livsforløbet med, og man kan derfor komme til at undervurdere den samlede miljøbelastning, hvilket viser sig ved sammenligning med I/O-analyserne. Heller ikke livscyklusvurderingerne går helt fri af problemer med at fordele miljøpåvirkninger på enkeltprodukter. Der er nemlig mange processer, der ikke kun producerer ét produkt, og så må man alligevel til at lave nogle antagelser om fordelingen af processens miljøpåvirkninger på det enkelte sam-produkt.
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More than 10% of global GHG emissions are related to land use changes (LUC). This is almost the same as global GHG emissions from transport and around half of global GHG emissions from electricity produced from coal. The magnitude of LUC emissions clearly indicates that excluding this from LCA is highly problematic. In addition, several LCIA methods suggest that land use related impacts are much more important than GHG emissions (Weidema 2015). This makes the exclusion of LUC from LCA even more problematic.
Often, the impacts from indirect land use change (iLUC) are lacking in LCA studies – or at the best, it is modelled without reasonable considerations on cause-effect relationships between the use of land and the induced effects. If iLUC impacts are not included properly in the LCA results, there is a great risk of producing misleading results. Therefore, there is an urgent need for a good generic way of modelling iLUC. This should not be limited to biofuels or some certain crops in a certain region. There is a need for a generic model that can be applied to all kinds of land using LCA processes (cultivation of crops, cattle grassland, forestry, and land for buildings and infrastructure).
In order to make such a model available, we established the iLUC Club in 2011, which now has more than 20 universities and companies as members. We are currently working on the fifth version of the model which makes use of global land use change matrices and satellite data. The model framework is documented in a peer reviewed scientic article: A framework for modelling indirect land use changes in life cycle assessment. The model has been compared with other iLUC models in a scientific paper, where it was ranked as the best performing with regard to several criteria. Further, we actively contribute to the ongoing scientific debate on iLUC.
The model strives towards establishing a cause-effect relationship between, on the one side:
and on the other side:
The model has been tested and applied in several studies:
Subscription to the iLUC Club gives access to:
An important open source output from the project is a file with the needed information for obtaining iLUC GHG emission data for any land use (arable, forest, grassland) in any country in the world (download file).
The current members include:
On occasion of the 10th anniversary of our engagement with iLUC (15th Nov. 2017) we held a free webinar - the recording from this webinar can be seen here (youtube video) and the slides here (pdf).
For subscription (or questions), please contact us. To go to the club click here.
The aim of the study is to develop a tool, which can be used for calculation of carbon footprint (using a life cycle assessment (LCA) approach) of milk both at a farm level and at a national level. The functional unit is ‘1 kg energy corrected milk (ECM) at farm gate’ and the applied methodology is LCA. The model includes switches that enables for, within the same scope, transforming the results to comply with 1) consequential LCA, 2) allocation/average modelling (or ‘attributional LCA’), 3) PAS 2050 and 4) The International Dairy Federations (IDF) guide to standard life cycle assessment methodology for the dairy sector. The key elements of consequential LCA and the IDF guide are presented and explained by examples. The national carbon footprints (CF) for milk produced in Denmark and Sweden in 2005 are presented.
Tidligere undersøgelser har konkluderet, at en forudsætning for en produktorienteret miljøindsats i primærlandbruget er, at der kan beregnes nøgletal for miljøpåvirkninger pr. produkt. Denne forudsætning er nu opfyldt med et nyt værktøj til miljøvurdering af produkter fra landbrug. Med udgangspunkt i de data, der findes i grønne regnskaber for landbrug, kan der beregnes nøgletal for de væsentligste emissioner og miljøpåvirkninger, der er forbundet med produktion af landbrugsprodukter. De væsentligste miljøpåvirkninger er vurderet til at være drivhuseffekt, forsuring, næringssaltbelastning, økotoksicitet og arealforbrug. En miljøvurdering viser, hvilke emissioner og hvilke kilder til emissioner, der potentielt kan påvirke miljøet mest. Nøgletal pr. produkt kan anvendes til bench-marking mellem landbrugsbedrifter og kan udgøre grundlaget for en produktorienteret miljøindsats i primærlandbruget. Miljøvurdering af produkter fra landbrug sætter landbrugets miljøpåvirkninger ind i et helhedsperspektiv.
Emnet for denne vejledning er nogle af de første elementer i en livscyklusvurdering, efter at man har defineret undersøgelsens mål (se også Figur 2), nemlig:
Disse elementer kan ofte være afgørende for resultatet af en konkret livscyklusvurdering. Derfor er det vigtigt at disse elementer udføres med omhu.
Formålet med denne vejledning er at tilvejebringe en entydig procedure for disse elementer i en livscyklusvurdering.
De omtalte elementer tjener tre formål:
En livscyklusvurdering undersøger miljøpåvirkningerne ved en mulig pro- duktsubstitution, dvs. et valg af ét produkt frem for et andet, eller et valg af et bestemt produkt i forhold til et fravalg af dette produkt.
Den funktionelle enhed beskriver og kvantificerer de egenskaber ved produktet, der skal være til stede, for at den undersøgte substitution kan finde sted. Disse egenskaber (funktionalitet, udseende, stabilitet, holdbarhed, osv.) bestemmes igen af kravene på det marked, hvor produktet skal sælges.
Referencestrømmene omsætter den abstrakte funktionelle enhed til konkrete produktstrømme for hvert af de systemer der sammenlignes, således at produktalternativerne sammenlignes på et ækvivalent grundlag, der afspejler de faktiske konsekvenser af den mulige produktsubstitution. Referencestrømmene er udgangspunkt for at opbygge de nødvendige modeller af produktsystemerne.
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