Men did not make the earth. ... It is the value of the improvements only, and not the earth itself, that is individual property. ... Every proprietor owes to the community a ground rent for the land which he holds.
Economics is not simply a topic on which to express opinions or vent emotions. It is a systematic study of what happens when you do specific things in specific ways. In economic analysis, the methods used by a Marxist economist like Oskar Lange did not differ in any fundamental way from the methods used by a conservative economist like Milton Friedman.
Thomas Sowell, Ch. 1 What is Economics? in Basic Economics
Depletion and the negative environmental impact of fossil fuels are the main drivers behind the quest for renewable energy technologies. EU-funded scientists studied the potential of newly developed prototype devices to exploit geophysical flows.