Looking at the available metrics, it turns out that indicators are often limited to one or two dimensions of sustainability, predominantly environment and economics. Economic metrics
are available in the market economy and are typically integrated in company and national reports. With respect to environmental sustainability, the predominant metric that was developed in the 1980s and 1990s is environmental life cycle analysis (Chapter 6). In this era, concern about the environmental effects of technologies was focused on emissions. As an illustration, typically seven out of eight themes of the life cycle assessment method are emission-related: global warming, ozone depletion, acidification, eutrophication, photochemical oxidant formation, human toxicity and ecotoxicity; one single theme was resource depletion. Today, in an era where sustainability principles dominate and where waste reduction technologies are common practice, growing emphasis on resource depletion is expected. In this sense, environmental metrics need to be rethought. Finally, integration of social indicators in renewables-based technology assessment is much more limited and will need further exploration.