Main processes at the Gendorf site include the production of surfactants from fatty acids and fatty alcohols, membrane electrolysis of rock salt, the production of vinyl chloride monomers and polyvinyl chloride (PVC) from ethylene and chlorine, the production of ethylene oxide and ethylene glycol from ethylene, air separation to supply chemical reactions with oxygen and produce liquid nitrogen, and the liquefaction of some of the CO2 that originates from the ethylene oxide production. Minor processes include the production of polymer films from various types of polymers and the production of fluorine chemicals such as polytetrafluoroethylene (PTFE) from chlorodifluoromethane. The ecoinvent proxy approach. In the ecoinvent modeling approach, the data from the Gendorf site was processed via three main steps to then be used as proxy. First, the total production volume of the site was determined by adding up the intermediate and final outputs at the site . The Gendorf site produces chemicals largely from external inputs that are produced elsewhere, and the processes at Gendorf generally involve only a small number of synthesis steps. Thus, the total product output, including the intermediates used for the creation of the ecoinvent proxy approach, is only about 64 % higher than the amount of final outputs of the site . In a second step, the reported utility demands of the Gendorf site (electricity, heat, natural gas, cooling water, nitrogen and wastewater treatment) are divided by the total chemical production volume of the site to yield the average amounts of utility inputs and outputs per production output mass as proxies, and the water balance is closed. In the case of infrastructure requirements, satellite imagery has been used by ecoinvent to identify the occupied land area for the Gendorf and Ludwigshafen sites, which was then divided by the estimated number of production plants at the two sites . Together with the estimated plant lifetimes, the building infrastructure based on satellite imagery and the inventory of an existing chemical plant, the land occupation, land use change and building infrastructure requirements were estimated for one chemical plant. The production volumes and the plant lifetime estimates then linked the land occupation, land use change and building infrastructure requirements with a specific amount of chemical production as proxies.