I think a system of agriculture and renewable energy which is both sustainable and allows for some material comfort will determine the right population for a region. Some lo tech approaches such as jatropha based biodiesel and methane digesters haven't yet created a new middle class. Conversely hi tech biofuels such as cellulosic ethanol or Fischer-Tropsch diesel may be out of the reach of poor communities and perhaps may never be practical even for the wealthy. Either way biofuel has only a modest return on labour or capital and needs to be integrated with low emissions electricity such as plug-in hybrid cars. My guess is that the world can only support perhaps two billion people with decent amounts of food, shelter and personal transport. Since these basic needs compete for the same soil and water it doesn’t help that there are more and more of us.

'Joachim-von-Braun,-a-citizen-of-Germany' says to get policies right for developing countries...so too in Australia. Agricultural policies force farmers to accept prices which are rendering Australian farmers the lowest-paid-workers (and-longest-working)in the country...alongside self-funded-retirees, averaging $15,000pa. income.

Australian input costs and environmental requirements make agricultural pursuits amongst the most expensive to maintain in the world, yet the Aussie farmer receives a fraction of what farmers in von Braun's native Germany receive under the highly-subsidised EU-CAP. Aussie farmers remain amongst the-most-efficient-in-the-world or in many sectors, head-and-shoulders-above-the-rest. The manufacturing and retail sector is where the cost blowouts are in Australia, with the two major supermarket chains making mockery of the so-called National Competition Policy. Between the two of them they have dictated the terms to governments of both political persuasions, with in excess of 90% of the retail market...so much for increasing competition or 'clout' for our farmers or lowering prices for consumers, the results prove the reverse.

Von Braun can include Aussie farmers amongst those needing policy consideration as there's little chance Aussie sugarcane-farmers will share in returns from a biofuels industry unless the present inequitable policies of government address the very real corporate greed and bullying that is rampant in the retail and corporate sector against Australian farmers.

For ethanol to be produced from sugarcane, grain and 'cellulose' from residues of crops, farmers must be included in the profit mechanism or there will be a shift to a plantation-style farming debacle like the Philipines and elsewhere, with poverty and penury in rural Australia already growing steadily along with the rural suicide rate!

Ethanol has proven itself environmentally and fiscally, it remains to be seen if the governments of the day have an agenda that seeks to rid Australia of all other than the corporate masters who are dictating policies through their political donations.

The recent fiasco with Growcom and the 'voluntary code of conduct' for fruit and vegetable retailers is a classic case, where the two main offenders, Coles and Woolies were left out of the arrangements at the eleventh hour...I guess those political donations were too hard to ignore.

Taswegian suggests bio-fuels are too expensive to produce and there are too many people to maintain on our planet.

Given the worldwide mismanagement of resources and blatant waste and greed of the corporate players who direct government, the solution to poverty with today's population and a reasonable existance for all on the planet is well within the realms of probability, what is lacking is the will of governments and the greed-driven corporate sector to allow or encourage it to happen.

As for the fiscal side of the bio-fuels debate, the production of ethanol from sugar cane is already comparable to fossil fuels and will also produce environmental benefits in cleaning up fuel emissions, even with low levels of ethanol added. Countries like Brazil have proved the economics and the environmental worth of the product as have other countries like Sweden, the US and the lists go on.

You shouldn't believe all the propaganda on population and bio-fuels you read, Taswegian, it's a lot of red herrings designed to distract you from the facts...

Bio-diesel from oil palm has a large number of fans. The horizon-to-horizon clearing of rainforest in Indonesia and Malaysia to make way for oil palm plantations doesn't seem to attract much attention from renewable fuel supporters.