Acidification, life cycle assessment

Life-cycle assessment when carried ont according to the ISO rules has shown its ability to deliver data for certain more global environmental compartments like the impact potential on saving of resonrces, global warming potential, acidification, ozone depletion, and the like. It nsnally does not cover local effects such as noise or smell and hazardons snbstances. Here risk assessment or other methodologies are needed. The evalnation of effects regarding human toxicity is hampered by a lack of sufficient data and by a still undecided question of data evaluation. Thns, life-cycle analysis is a nseful tool but not the only answer to all enviromnental aspects. 

Life cycle assessment (LCA) is a methodological framework for estimating and assessing the environmental impacts attributable to the life cycle of a product, such as climate change, stratospheric ozone depletion, tropospheric ozone (smog) creation, eutrophication, acidification, toxicological stress on human health and ecosystems, the depletion of resources, water use, land use, noise, and others [3,4]. 

To gain a comprehensive view of the true environmental impacts of products and processes requires life cycle assessment (LCA) studies to be performed. Parameters that are measured as part of a LCA include total cradle mass (amount of materials taken from the earth), energy requirements, greenhouse gas emissions (GHG), photochemical ozone creation (POCP), eutrophication, acidification, and total organic carbon (TOC). ° Full LCA is extremely time-consuming and life cycle inventory (LCI) data is often difficult to acquire, in particular for bioprocesses in terms of substrates and enzymes. ... 

The inventory results should be presented in clear form, how much and what substances from the environment enter the system and how much get out. These results serve for subsequent life cycle impact assessment [48], The aim of the life cycle impact assessment is to measurably compare the environmental impacts of product systems and to compare their severity with new quantifiable variables identified as impact category. The impact categories are areas of specific environmental problems such as global warming, climate changes, acidification, eutrophication, ecotoxicity and others. Already in the phase of definition of the LCA study scope, it is necessary to describe what impact category will be applied and which of their environmental mechanisms will serve as a basis for impact assessment [46],... 

As mentioned above, there are characterization factors for a number of different impact categories, e.g. acidification, eutrophication, climate change, human toxicity and ecotoxicity. However, characterization factors are missing for many additives, especially for human toxicity and ecotoxicity, which makes it difficult to assess the potential impact that a product will cause during its entire life cycle. A major reason that characterization factors are often missing is the lack of data regarding substance properties, such as physical chemical properties and toxicity. 

These indicators have been developed mainly to be applied at the industry level, for monitoring and benchmarking, using economic value to measure products or services. Another difference is that, while EATOS and the EQ summarize environmental impact as a general attribute, expressed by potential environmental impact/ environmental unfriendliness factors, IChemE indicators measure particular environmental problems, such as toxicity or acidification. This problem-oriented approach used by IChemE is based on the Life Cycle Impact Assessment framework that will be discussed later. 

Potting, J., Schlopp, W., Blok, K., emd Hauschild, M. (1998), Site-Dependent Life-Cycle Impact Assessment of Acidification, Journal of Industrial Ecology, Vol. 2, No. 2, pp. 63-87. 

Van Zelm, R., Huijbregts, M.A.J., Van Jaarsveld, H.A., Reinds, G.J., De Zwart, D., Stniijs, J., Van de Meent, D., 2007b. Time horizon dependent characterisation factors for acidification in life-cycle impact assessment based on the disappeared fraction of plant species in European forests. Environmental Science and Technology 41, 922-927. 

Most LCAs are performed only xmtil Step 2, since impact assessment and interpretation involve many more qualitative assumptions. In this case, LCA are called life cycle inventories (LCIs). This latter is a tool required to estimate the direct and indirect inputs of each step of a biofuel pathway. The results are the use of resources (eg, energy consumption) and the environmental emissions (eg, CO2, sulfur oxides, nitrogen oxides). LCIs permit the assessment of impact categories, such as climate change, photooxidant formation, acidification, eutrophication, ecotoxicity and human toxicity, and the depletion of biotic and abiotic resources. These factors of the LCI will be converted into environmental damages. Various indicators can be derived from these mechanisms at intermediate levels (midpoints) or damage levels (endpoints) after normalization, often weighting approaches. 

The LCA study of ethanol focused on the evaluation of (GHG) emissions. Meanwhile, Life Cycle Impact Assessment (LCIA) studied the impacts (eg, global warming potential, ozone depletion, acidification potential) resulting from the LCI study. Finally, depending on the results obtained in the LCI and/or LCIA, many suggestions and recommendations can be offered. GHG emissions of biofuels are expressed per MJ of unit output. 

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