Sustainable development is a simple business idea. An enterprise should grow its own capital. A new machine replaces an old machine. Only if the new machine is cheaper or more productive, should the owners take more out of the business and consume more than they did when they used the old machine.
In the energy business, producers of fossil fuels are expected to ﬁnd new reserves, or increase the efﬁciency of extraction from old reserves, to replace those they deplete. If they do not, the stock markets will mark them down as companies with a shrinking future. Some companies have disappeared, for example those that depleted the oil and gas reserves of the United States and failed to replace them with reserves elsewhere.