Lecture: Advanced Environmental Assessments Attributional and consequential LCA 1 October 1, 2015 www.ifu.baug.ethz.ch 1
A statement From a purely statistical viewpoint, the poet said, being a non-smoker I could smoke for about seven years longer than a smoker. 2
What we will learn today Know the properties of different LCI models Know when and how to apply them in different contexts Apply the models on a case study (exercise) 3
Content Typical LCA questions Attributional approach Consequential approach Decisional approach Exercise 4
Three different life cycle inventory models attributional (Heijungs 1997) consequential (Ekvall & Weidema 2004) decisional (Frischknecht 1998/2010) Rahmen einer Ökobilanz Life Cycle Assessment Framework Goal and Scope Definition Sachbilanz Inventory Analysis Auswertung Interpretation Direkte Anwendungen: - Entwicklung und Verbesserung von Produkten - strategische Planung - politische Entscheidungsprozesse - Marketing - sonstige Festlegung des Ziels und des Untersuchungsrahmens Wirkungsabschätzung Impact Assessment 5
The attributional approach 6
Characteristics The attributional approach attempts to provide information on what portion of global burdens can be associated with a product (and its life cycle). In theory, if one were to conduct attributional LCAs of all final products, one would end up with the total observed environmental burdens worldwide. The systems analysed ideally contain processes that are actually directly linked by (physical, energy, and service) flows to the unit process that supplies the functional unit or reference flow. 7
Typical goal and functional unit Which environmental impacts can be attributed to the production of a litre of Max Havelaar (MH) orange juice consumed in Switzerland in 2012? The product analysed (one litre of MH orange juice) is part of the total consumption volume of MH orange juice in Switzerland in 2012 (9.0 Mio. litres) 8
Procedure Identify all economic actors that contributed to the supply of MH orange juice in Switzerland in 2012: - orange farmers, - juice producers, - juice carriers, - packaging materials suppliers, etc. 9
Procedure (cont.) For all economic actors collect information about their (yearly) average consumption of: - raw materials, - working materials, - energy, - waste treatment services, and - transport services their (yearly) average release of: - airborne pollutants, - waterborne pollutants, and their (yearly) average output of products 10
Conventions The production functions applied are linear homogeneous impacts (A) + impacts (B) = impacts (A+B) doubling product output => doubling impacts inputs and outputs (incl. investment requirements) are equally allocated to all units of a production volume 11
Examples Sustainability report of Geberit International Environmental profile of average Swiss electricity mix 2012 supplied to the plug ecolabelling of green electricity according to naturemade star 12
The consequential approach 13
Characteristics The consequential approach attempts to provide information on the environmental burdens that occur, directly or indirectly, as a consequence of a decision (usually represented by changes in demand for a product). In theory, the systems analysed in these LCAs are made up only of processes that are actually affected by the decision, that is, that change their output due to a signal they receive from a cause-and-effect chain whose origin is a particular decision. 14
Goal and functional unit How will flows from and to the environment (on a global level) change when introducing a MH orange juice target in Europe (e.g. 20 % of consumption to be MH by 2020)? Does such a policy lead to reduced environmental impacts? The product analysed (one litre of MH orange juice) is NOT part of the current consumption volume of MH orange juice, but part of an additional consumption (as a result of the policy implementation). 15
Elements of consequential modelling (Ekvall & Weidema 2004) allocation for multifunctional processes allocation for open loop recycling alternative use of constrained production factors general market effects identification of the competing product identification of marginal technology technology development 16
allocation for multifunctional processes Consequential LCA of product A: Product A and B produced independently Production of product B depends on demand in product A Production of product A depends on demand in product B 17
Product A and B produced independently Example: change in demand for fossil diesel Apply physical causal relationships 18
Production of product B depends on demand in product A Example: increased demand for beef meat Increase in B: Production of C is avoided 19
Production of product A depends on demand in product B Eample: sheep wool insulation material Multifunctional process not affected by increase in A avoided alternative use increased use of substitute D 20
allocation for open loop recycling Increased recycling input: avoided waste management or reduced use in other products Increased post consumer recycling: avoided virgin production or reduced recycling of other products 21
allocation for open loop recycling Increased recycling input: avoided waste management or reduced use in other products Increased post consumer recycling: avoided virgin production or reduced recycling of other products 22
open loop recycling: a market for recovered material 23
Price elasticies: Supply (S) and Demand (D) Example: Supply increases by 1% if price increases by 10%: h s = 0.01/0.1 = 0.1 Demand decreases by 0.5% if price increases by 10% h D = -0.005/0.1 = -0.05 24
Price elasticies: empirical data on recycled materials Ekvall 2000 25
Effects on Supply and Demand: Change in recycled material available Example: amount of recycled material available ( X) changes by 1000 tons Demand increases by 1000 t * (-0.05)/(-0.05-0.1) = 334 tons Supply decreases by 1000 t * 0.1/(-0.05-0.1) = -666 tons Additional supply absorbed by additional demand (1/3) and lower supply from others (2/3) 26
1 000 tons Effects on Supply and Demand: 1 000 tons more recycled material available 27
Price elasticies: simplifications 28
alternative use of constrained production factors increased use of constrained factors: reduced alternative uses or increased supply by alternative products 29
Constrained production factors: the wood example 30
Identify marginal technology relevant time aspects (short term / long term) specific processes or overall markets If overall market: identify trend in the market (expand / shrink) identify flexible technologies natural, political, market constraints identify technology actually affected 31
Identify marginal technology in expanding markets: next technology to be installed technologies with lowest production costs in shrinking markets: next technology to be shut down technologies with highest production cost 32
Example: marginal electricity mix Outline and goal A company purchases green electricity Challenge of using electricity inefficiently and not investing in electricity saving measures marginal electricity mix for investment decisions Identify possible marginal electricity mixes for the company Provide arguments for the communication 33
marginal electricity mix Switzerland: Mix today and in 2050 34
Thinking models marginal electricity mix which technologies increase production? which technologies produce less electricity? Using electricity more efficiently has the following consequences: less new power plants need to be built existing power plants can be taken from the grid earlier Three options: Growth: only technologies with increasing production (from today to 2050) Reduction: technologies, which produce less Change: technologies, which change their production 35
Derivation of marginal electricity mixes 36
Derivation of marginal electricity mixes 180 160 140 120 100 80 60 40 Neue Erneuerbare, Zunahme Neue Erneuerbare Wasserkraft, Abnahme Wasserkraft Kernenergie, Abnahme Kernenergie Fossil, Zunahme Fossil 20 0 Heute 2050 37
Further approaches Arguments: Saving electricity allows to reduce electricity production from fossil and nuclear power plants Comparison of different future scenarios economic consideration: Growth: power plant with lowest private costs (per kwh) Reduction: power plant with highest operational costs (per kwh) 38
Proposed marginal electricity mixes Swiss energy strategy 2050, BAU: efficient use of electricity allows for less investments in in Switzerland under unchanged political conditions marginal mix is represented by natural gas power plants, hydro power and pumping storage ewz electricity future 2050, scenario 3: efficient use of electricity allows ewz for less investments in renewable energies marginal mix is represented by increase of renewable power plants residual non renewable electricity mix Europe: efficient use of electricity allows for exporting renewable electricity Europe may reduce production with fossil and nuclear power plants marginal mix is composed of hard coal, lignite, oil, gas and nuclear 39
Examples of marginal electricity mixes 40
Decisional approach 41
typical question Which environmental impacts can be attributed to an extra consumption of Max Havelaar orange juice to be purchased in Switzerland? How does the environmental profile of a canteen change if changing from conventional to MH orange juice? 42
Basic underlying concept Main basis of information for building up the product system in the LCI are (anticipated) financial and contractual relations between economic actors (b2b relations) Paying a supplier I receive intermediate goods and services and the environmental burdens associated with them 43
Procedure Identify the MH farmers, juice producers, carriers, packaging material suppliers that will contribute to the production of MH orange juice I decide to purchase from. 44
Main difference to consequential approach Even if the product output of MH farmers, juice producers, carriers, or packaging material suppliers were constrained (cannot be increased), their inputs and outputs will be considered. => LCA of MH orange juice always reflects production of MH orange juice. 45
Summary 46
Summary Attributional LCA aims at describing the state of flows in the economy and to and from nature. Consequential LCA aims at supporting macroeconomic policy decisions (usually large-scale in view of reducing environmental impacts on a global scale). Decisional LCA aims at supporting decisions in companies to improve the environmental performance of their products or processes 47
Sitting on the lakefront 48
Classification of LCA objects of investigation Using the relative economic size: Size of the object of investigation compared to: annual consolidated turnover in a region (e.g. EU-27 or Page 49 Switzerland) monetary purchase volume from relevant economic sectors physical purchase volume from relevant economic sectors >1% <0.1% <1% <1% <0.01% 49
Which approach in which situation? Frischknecht & Stucki (2010) economic size relative share recommended LCI model Small: individual consumer decisions < 0.1 % attributional Medium: corporate strategic planning 0.1 % to 1 % decisional; attributional in a sensitivity analysis Large: international policy making > 1 % consequential Page 50 50
Exercise: LCA of BR soybean biodiesel European Union: substantial increase in demand of soybean continuous extension of cultivated area extension based on conversion of shrub land and clearcutting of tropical forests Unit Brazil Soybean yield kg/ha 2'544 existing agricultural land m 2 /kg soybean 3.73 agricultural land, transformed from tropical forest m 2 /kg soybean 0.062 agricultural land, transformed from shrub land m 2 /kg soybean 0.10 total agricultural land required m 2 /kg soybean 3.93 51
Increase of agricultural area This area was cleared by soybean farmers in Novo Progreso. Brazilian Government figures show that the rate of clearing has increased. 52
Annual forest loss in Brazilian Amazon nearly 20 000km 2 = 600m 2 per second http://rainforests.mongabay.com/amazon/deforestation_calculations.html http://sitemaker.umich.edu/section2group3/results_and_discussion 53
Basic information: Clear-cutting loss of carbon stocked in soil: 12.3 tons C per hectare converted burning 20 % of the primary forest biomass: 120 000 kg CO 2 per hectare products: - 1 hectare of agricultural land - 53 m 3 round wood 1m 3 primary forest wood may replace 1m 3 scandinavian wood 54
Basic information: soybean oil production 1kg soybeans results in - 0.19 kg soybean oil - 0.76 kg soybean meal market prices of products (basis for economic allocation): - 1 270 R$ (Real) per ton soybean oil - 445 R$ (Real) per ton soybean meal 1 kg soybean meal may replace 0.9 kg corn in cattle rising (fodder) 55
Basic information: diesel fuel supply and use life cycle based greenhouse gas emissions (excluding car manufacture, road construction and maintenance) 1kg soybean-based biodiesel used in car: 1.85 kg CO 2 -eq per kg excluding contributions from land transformation and coproducts 1kg fossil diesel used in car: 3.7 kg CO 2 -eq per kg 56
Questions Which are the different ways to model and quantify land transformation and co-products manufacture? Which approach should be followed? Draw flow chart How does additional BR soybean biodiesel perform compared to fossil diesel? 57