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life cycle assessmen
Prepare for finals
| Question | Answer |
|---|---|
| What is a life cycle assessment? also known as? | technique to assess environmental impacts associated with all stages of a product's life "cradle/ conception to grave" perspective |
| 3 ways life cycle assessments are important | 1. avoid unintended consequences 2. help examine how change will effect entire system 3. provide estimates of energy and climate change emissions for certification processes |
| 3 Types of life cycle assessments | 1. Process based LCA 2. Economic input output LCA 3. Hybrid LCA |
| Process based LCA | consistent and comprehensive accounting of - material - energy - waste flows related to a given product |
| What are three key elements to LCAs | 1. Goal, definition and scope 2. life cycle inventory 3. impact assessment |
| What is the goal and scope definition? | goal: purpose, method of LCA, includes audience, application, goals/ objectives and how results are interpreted Scope: function and functional unit- the system boundaries, the data requirements, assumptions and limitations and report format |
| functional unit is extremely important, why? | defines what products are comparable to one another - light bulbs, must compare bulbs with same luminescence - gallon of ethanol can be compared with gallon of petroleum |
| system boundaries | which unit process and parts of the life cycle should be included in the study- same playing field ex: 2 carpet fibers recycled and new, should we compare their use in the building or just manufacturing |
| system boundaries in biofuels | system boundaries in biofuels have hanged over time to reflect changing goals 1. first omitted greenhouse gas emissions- only energy 2. GHG emissions then included but field derived emissions weren't included 3. field emission and land use change are a |
| describe how field emissions and land use changes are now important components of a biofuel's LCA | - food source and plant source= pretty direct - if I use nonariable land, should I get more credit? |
| unintended concequences of land use changes around the world, required to produce new crops because existing production is used for ethanol or biodiesel production is known as: | ILUC indirect land use changes ex: amazon and sugar cane |
| setting the system boundary | - increase amount of stuff we incorporate increases complexity and ACCURACY - equal size system boundaries and key assumptions = fair playing ground and answer important questions--now and in the future - number skewing: buying the corn not producing it |
| life cycle inventory assessment | amount/ quantification of 1. input: primary materials, recycled, energy 2. output: co products, air pollution, water effluents, solid waste for given product system throughout its life cycle |
| 2 key challenges for LCI | LCI= life cycle inventory 1. variability and uncertainty in life cycle inventory data sets 2. treatment of co- products |
| 1. What is bitumen? 2. why is there variability in life cycle inventory databases? | 1. tar sands 2. they don't take things into the same account - different refining and transportation processes 1. real world differences 2. uncertainty |
| during the production process of a product, we often find that more than one product results from the process. This is the? | - treatment of co- products |
| How do we deal with co- products? | 1. allocate burdens appropriately based on 1. value (old school) 2. system expansion 3. displacement |
| What does system expansion have to do with co- products? | - using coproducts= subtract environmental burdens of alternative way of producing the co product - coproduct have some value, gives credit to primary product |
| What is the main co- product of ethanol? Business as usual: coproduct: | Dry distiller's grains and solubles (DDGS) - corn and soybean meal - corn and DDGS |
| co product treatment | - makes ethanol more credible - energy based allocation - system expansion: different displaced products |
| why is co- product treatment challenging? | - there's an infinite number of "right answers" - dynamic market affet displacement and economic allocation methods - indirect and complex effect when we introduce large quantities of a co- product in a market |
| co- product and system dynamics related? | - coproduct displaces something else in the market - cow feed and DDGS can compete for price of feed |
| impact assessment | translates life cycle inventory into meaningful metrics that tell us about system's impact on the environment and human health - can be applied to both inputs and outputs |
| impact assessment: list inputs and outputs | 1. abiotic resource extraction 2. biotic resource extraction 3. land use 4. fossil and total primary energy 1. global warming 2. stratospheric ozone depletion 3. human toxicity 4. ecotoxicity 5. photo- oxidant formation 6. acidification 7. nut |
| how does recycling help? | paper vs. plastic, paper has less LDPE per bag but if you recycle plastic bags then it will have less environmental impact |
| In general LCA tells you what? | 1. how good your process is 2. what's the bottle neck in your process |
Created by:
sunying12
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