Some environmentalists and economists argue in favor of a sustainable economy.  This system has a variety of implications, but basically means that the population and quantity of goods would remain constant over time.

First, it means that the society would desire a constant GNP, with some sectors growing and others declining at an equal and opposite rate.  Overall, the economy would continue to achieve the same level of output each year.

Those sectors of the economy that increased the sustainability of the environment, such as renewable energy or the production of long-lasting goods, would be encouraged to grow.  If new technology made growth possible without decreasing sustainability, growth would be allowed.

Second, the country would try to maximize the use of renewable resources.  This would mean relying on wind, water, the sun, or another renewable resource for power production, rather than burning fossil fuels, of which there are limited supplies.

Third, the sustainable economy would seek to achieve economic and ecological sustainability.  It would view biological capital as being of equal importance to financial capital.

Fourth, an incentive system would be used to reward those who minimize the toll they exert on the environment, and produce long-lasting items for human use.  Materialism would be discouraged, and people would be encouraged to use only essential goods and services.

Rather than consuming our natural resources, the sustainable economy would seek to use what we have already taken, and leave natural resources as a backup supply.

Finally, a sustainable economy would attempt to build a more egalitarian society.  While trying to minimize the number of goods people used, the economy would also try to equalize what goods people had.

A web site on sustainable development