In terms of entropy, the two most important physical limits are local over-heating due to limited entropy export capacity and the minimum entropy reduction requirement for concentration of very dispersed materials. The first may be a problem for the local environment around power plants and in cities. For the Earth as a whole, the limit on the rate of entropy export is inessential.
From:
Entropy and economic processes — physics perspectives by Tomas Kåberger and Bengt Månsson, Ecological Economics Volume 36, Issue 1, January 2001, Pages 165-179
Isolated systems may face absolute limits and 'collapse' under the weight of increased entropy. Open systems, like the Earth, with external sunlight and dissipating heat to space, does not.
