Try two facts.
First, if all the Chinese in China used as much energy as the average American, the world's fossil fuels would in run out in seven years. Not to worry, nothing like all of them will. It won't happen.
Secondly, though, China's urban population increases by the size of Birmingham once a fortnight.
These people don't use as much oil, electricity, gas, coal, or whatever as their American, or Brummie, counterparts. But they would like to have a shot at it.
They have come to town in pursuit of 21st century urban prosperity. That means using energy on a scale nobody dreamed of before, even ten years ago.
It is not just China, nor just China and India. They are the countries that catch the headlines, but it is happening to varying degrees everywhere. City life has an irresistible attraction the world over.
These facts come from Robin Batchelor and Poppy Allonby, who run the Merrill Lynch New Energy Technology Trust, a £92 million investment trust, seeking to make money investing in companies working to close what looks like opening into a yawning energy gap.
Saving the planet comes into it - but at one remove. Mr Batchelor takes care to point out that he is not running a "green" fund.
Strictly "green" products, in his view, rarely make good investments. Like other fund managers, he is looking for companies with economic products.
It is surging demand for energy of any kind that has made alternative energy economic - but the political imperative to do what can be done about global warming does provide a helpful and sustained macro-economic backdrop.
Turning coal - the most plentiful source of fossil energy - into diesel becomes economic once oil costs $40 a barrel. It wasn't three years ago. It is now, and looks like staying that way with a fair margin to spare.
With oil in the $50-$70 a barrel bracket, wind power is actually cheaper, level-pegging with natural gas. Whether it is so when delivered by a little propeller whizzing on the roof of "green Dave" Cameron's home may be something else - but that there to generate publicity rather than electricity.
Hydro-electricity (and come to that nuclear, though it is outside the "New Energy" remit) costs about the same as coal. Much-publicised bio-mass ranges from just above the coal bracket just above the oil bracket, depending on the form it takes. Mr Batchelor reckons ethanol has been overdone for the moment and has been taking profits on it.
Solar power is the expensive option, but attracts Government subsidies.
For investors, the catch with alternative energy is that many of the companies in it are small, foreign, or young. Many are not yet profitable. The Merrill trust has had an impressive run with them over the past three years, with a share price rising by more than 200 per cent. But before that it took a terrible drubbing. It was launched in October, 2000, just as the bear market was getting into its stride.
The logic is compelling, but not for the faint-hearted.