Environmental impacts of OPVNieves Espinosa Martinez
An environmental impact is an adverse consequence associated with inputs of resources and outputs of pollutants across the product life cycle. For example, the combustion of diesel fuel in the trucks/ships to transport materials to manufacture plastic solar cells releases carbon dioxide which leads to global warming.
The third step of an LCA study is the assessment of these impacts and how inputs and outputs derived from the previous inventories, are assigned to each of the impact categories. Impact categories considered in the so-called LCIA include climate change, ozone depletion, eutrophication, acidification, human toxicity (cancer and non-cancer related), respiratory inorganics, ionizing radiation, ecotoxicity, photochemical ozone formation, land use, and resource depletion.In Figure 1, there is an example of calculating the contribution to climate change from several gases. Each gas has different factors, 1 for CO2, 3 for CO and 25 for methane and so on, multiplying this factor by the amount of emissions results in kg of CO2 equivalent. This is the unit to measure the global warming potential.
There are more steps involved in the LCIA. After the characterization - modeling LCI impacts within impact categories using science-based conversion it is needed to do a normalization that is expressing potential impacts in ways that can be compared (e.g. comparing the global warming impact of carbon dioxide and methane for the two options). Then the grouping or sorting or ranking the indicators (e.g. sorting the indicators by location: local, regional, and global). Sometimes it is necessary weighting them, to emphasize the most important potential impacts.