Can engineering solutions really provide a sustainable future?

Sustainability is a word which is very often (mis)used in various public debates. In engineering, however, it is perhaps easier to define the term, then in other academic fields. We advocate the principle that only those activities, which can be sustained for at least a few centuries using known technology and resources, should be called sustainable. Using this definition of sustainability one particularly big challenge field is energy supply, but the importance of the issue - “The energy problem” - is clear.
To illustrate one central aspect of the energy problem we introduce the “1 TW benchmark”. On this backdrop we proceed to discuss the practical availability of chemical elements for energy technologies and the implications this has for industrial scalability. The issue will be exemplified by how some, otherwise promising, emerging technologies are limited in ultimate scale by scarcity of key elements. 1 Finally, we discuss a few specific recent research highlights from DTU-Physics within the field of energy harvesting and conversion.