Final Report Summary - GWAT-LCA (Revising the role of groundwater in life cycle assessment)
Compared to standard impact categories within LCA, water is special. In contrast to other abiotic resources such as coal or crude oil, it can be replenished. In contrast to CO2 emissions, there exists an immense spatial dependency of impacts on natural water bodies. Total global freshwater resources are sufficient, but not evenly distributed and often scarce in regions of high demand. Natural resources are difficult to assess if their value is not just local (e.g. on a community or industry scale), but on a societal level (like health effects). Setting up functional relationships in order to derive a generally valid and practicable evaluation is tedious due to the complex, insufficiently understood, and uncertain natural processes involved. This is also true for those effects and processes connected to natural water, or more particular, groundwater systems.
Consequently, one overarching goal here is to identify requirements of LCA procedures in relation to hydrogeology if groundwater is to be properly integrated. The result is a conceptual framework, which extends beyond a streamlined screening LCA. It is intended as an initiative leading to more sophisticated and robust LCA applications, which realise the existence and nature of the different hydrological compartments. Emphasis is placed on the 'safeguard environment groundwater', both with respect to its central role for human and ecological users and its role as receptor.
As a focal point, we concentrate on the most water consumptive sector, agriculture, and show how to compile the water-efficiency of cropping and regional water availability. As an illustrative example, global wheat farming is chosen, as wheat is one of the crops with the greatest acreage worldwide. Additionally, global water and groundwater use for more than 120 crops is assessed on a high spatial resolution. The regionalisation procedure is implemented as versatile Matlab/GIS model.
Furthermore, as second focus, we selected shallow geothermal energy use, related legal issues as well as technical, hydrogeological and environmental effects. Detailed modelling studies on natural heat transport at the land surface are presented, as well as new simulation techniques for closed-system ground source heat pumps (GSHPs). A comprehensive LCA of environmental impacts from GSHPs is published that reveals the dominant role of (primary) resource use, greenhouse gas emissions and particle matter formation related to power supply for the heat pump.