Now and again some commentator will claim that we lack to resources to support our population sustainably — either today or in the near future. But the fact is, even with current technology we have plenty of sustainable resources for our ~7 billion population and for the ~10 billion we expect in the future. What prevents this is not scarcity but folly and cruelty.

What are the constraints usually cited? There is soil and sustainable food production. But as I recently documented, we can feed ten billion sustainably if we choose to. There is freshwater, but as I documented, we have sustainable ways to deal with that as well.

What about energy? Right now we use about 14 terrawatts total primary energy world wide. The most conservative estimates of potential efficiency increases say we can double efficiency. And the most conservative estimates overlook stuff we are doing in some places at this very moment, including the potential for changes in material intensity and savings in thermal losses by producing electricity from mostly non-combustion sources.

But of course we are also going to have increased population and a lot of poor people who want to get richer. So it is not unreasonable to assume that a ten-billion-population world that consumes energy thriftily but lives a decent lifestyle with indoor plumbing, hot water, refrigerators, basic electronics, enough to eat, enough work, enough leisure, and plenty to do with that leisure will consume around 25 average terawatts worldwide.

About a quarter of this will be low-temperature needs for climate control, hot water, and perhaps refrigeration, 80% of which can reasonably be supplied by passive and active low temp solar thermal. That’s around 4 terrawatts. Existing hydroelectric plus new generators in existing dams plus geothermal can supply another terrawatt. Somewhere between 1 and 3 terrawatts can probably be provided by biomass in the form of methanol, biogas, or diesel and gasoline produced by the Fischer-Tropp process without competing with food or drawing down the remaining wild part of the biosphere — say, 1.5 terrawatts at a guess. If algae production becomes commercialized, we produce much more, but lets stick to proven technology that is less than double the current cost of fossil fuel.

That leaves 18.5 terrawatts to supply in the form of electricity.

According the Stanford Researchers, global commercial potential for wind is 72 Terrawatts at 80 meters, limited to sites with class 3 wind or better. Using about .29 percent of capacity on average, and allowing for transmission and storage losses, this would require about 3.7 million 5 megawatt wind generators. In contrast, the total number of oil and gas wells drilled worldwide is around 7 million.

Similarly, 18.5 terawatts generated via solar thermal in the desert would require about 3 percent of all desert land. Roads and parking alone require about a fifth of this.

Of course there is a great deal of other potential out there. Photovoltatics may soon become inexpensive enough that integrated cells on rooftops, south walls, windows, and so on can provide a significant percent of power. Geothermal, wave power, and various means of tapping ocean currents may soon improve radically. We may improve wind technology to the point where we can tap the jet stream. But even if none of the breakthroughs occur soon, it is obvious that wind (combined with major increases in efficiency), low-temperature solar thermal for domestic use (especially passive solar), and high temperature solar for electrical and certain industrial uses could easily meet all our needs through 2050.

Now, these are only some constraints. But the fact that we overcome these critical constraints sustainably is a strong indicator that we can overcome others as well.

That doesn’t keep population outstripping resources from being a possible long-term problem. But it is not a short-term problem.