Biofuels were given an important role in the Danish government’s energy and climate-change mitigation strategy (Energiaftale 2012). However, following a report questioning the carbon neutrality of different biofuels (Concito 2011), Concito is interested in assessing further the climate impacts of different biofuels. The current report includes Life Cycle Assessment (LCA) screenings for calculating the carbon footprint (CF) of six different biofuels: wood pellets, wood chips, straw, biogas, ethanol and biodiesel. Critical sources of emissions in the product systems of the biofuels, which are often excluded from LCA studies, are addressed in the current study. These include indirect land use changes (iLUC), time dependency of greenhouse gas (GHG) emissions, manipulation of the carbon in biomass and soil carbon.
The modelling of electricity in life cycle inventory has given rise to debates during the last decades. Significant issues in the debate are discussions on geographical delimitation of electricity markets, the question of whether constrained suppliers should be included, the modelling of co-products if electricity is co-produced with electricity, and in cases where the marginal supply is identified; the question whether the modelling should represent the short-term/production marginal or the long-term/build marginal. Many of the issues listed above are related to the different modelling assumptions applied in consequential and attributional modelling.
This methodology report provides qualified answers and recommendations regarding the above-mentioned issues. A generalized inventory methodology is outlined which enables for the application of consequential as well as attributional modelling assumptions. The inventory methodology described in the current report is applied to national and regional life cycle inventories. These inventories are presented in separate reports.
This paper discusses the identification of the environmental consequences of marginal electricity supplies in consequential life cycle assessments (LCA). According to the methodology, environmental characteristics can be examined by identifying affected activities, i.e. often the marginal technology. The present ‘state-of the-art’ method is to identify the long-term change in power plant capacity, known as the long-term marginal technology, and assume that the marginal supply will be fully produced at such capacity. However, the marginal change in capacity will have to operate as an integrated part of the total energy system. Consequently, it does not necessarily represent the marginal change in electricity supply, which is likely to involve a mixture of different production technologies. Especially when planning future sustainable energy systems involving combined heat and power (CHP) and fluctuating renewable energy sources, such issue becomes very important.
This paper identifies a business-as-usual (BAU) 2030 projection of the Danish energy system. With a high share of both CHP and wind power, such system can be regarded a front-runner in the development of future sustainable energy systems in general. A strict distinction is made between, on the one hand, marginal capacities, i.e. the long-term change in power plant capacities, and on the other, marginal supply, i.e. the changes in production given the combination of power plants and their individual marginal production costs. Detailed energy system analysis (ESA) simulation is used to identify the affected technologies, considering the fact that the marginal technology will change from one hour to another, depending on the size of electricity demand compared to, among others, wind power and CHP productions. On the basis of such input, a long-term yearly average marginal (YAM) technology is identified and the environmental impacts are calculated using data from ecoinvent.
The results show how the marginal electricity production is not based solely on the marginal change in capacity but can be characterised as a complex set of affected electricity and heat supply technologies. A long-term YAM technology is identified for the Danish BAU2030 system in the case of three different long-term marginal changes in capacity, namely coal, natural gas or wind power.
Four analyses and examples of YAMs have been used in order to present examples of the cause–effect chain between a change in demand for electricity and the installation of new capacity. In order to keep open the possibilities for further analysis of what can be considered the marginal technology, the results of four different situations are provided. We suggest that the technology mix with the installation of natural gas or coal power plant is applied as the marginal capacity.
The environmental consequences of marginal changes in electricity supply cannot always be represented solely by long-term change in power plant capacity, known as the long-term marginal technology. The marginal change in capacity will have to operate as an integrated part of the total energy system and, consequently, in most energy systems, one will have to identify the long-term YAM technology in order to make an accurate evaluation of the environmental consequences.
This paper recommends a combination of LCA and ESA as a methodology for identifying a complex set of marginal technologies. The paper also establishes values for Danish marginal electricity production as a yearly average (YAM) that can be used in future LCA studies involving Danish electricity.
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The land use required in order to meet the increasing demand for biodiesel has significant impacts. New methodological developments within environmental life cycle assessment (LCA) establish a cause–effect relationship between the demand for biodiesel and its impacts on biodiversity. The objective of this article is to assess and compare the impacts of rapeseed oil (RSO) production in the EU and palm oil (PO) production in Southeast Asia. The functional unit of the LCA is 20.8 Mtoe (million tons oil equivalents) biodiesel equalling the EU25 goals for biodiesel in 2020. Land occupation and transformation are quantified for the two alternative vegetable oils, and losses throughout the product chain from cultivation over crushing to refining are inventoried. Market mechanisms and land which is indirectly affected by product substitutions from co-products are included in the modelling. Land occupation and transformation are evaluated by the use of life cycle impact assessment (LCIA) models on land use and biodiversity. Three basic scenarios are evaluated: (1) RSO-based biodiesel is produced from rapeseed grown on fields which were previously grown by other crops (barley, BL) – the displaced BL is imported from abroad; (2) RSO-based biodiesel is produced from rapeseed grown on former set-aside land in the EU; and (3) PO-based biodiesel produced in Southeast Asia is imported to the EU. It is concluded that the new EU policies on using set-aside land for energy crops cannot cover the European demand for biodiesel and crops must thus be imported from outside the EU. This means that land use outside the EU is affected. The modelling shows that the use of PO affects the land use in Malaysia or Indonesia and that Canadian land use for BL cultivation is affected when rapeseed is produced in the EU. The impacts on land use and biodiversity are presented for all three scenarios. Finally, it is discussed how an LCA perspective like the one applied here can contribute to the assessment of environmental impacts within land use science.
