This sounds very promising. Of course it should be explored fully.

But I worry about the scale of operations necessary to replace fossil fuels, or even contribute significantly to their replacement, along with canola and various other biodiesel sources.

Saltwater ponds in the deserts would be plagued by water-supply problems.

Water that is too saline for irrigation or urban use could be utilised in some of our rivers and reservoirs. But I wonder what scale of operations are possible, at what further cost to the ecology of those rivers and their floodplains, and to what extent would it replace food-producing land, some of the best of which occurs on river floodplains and adjacent flatlands.

Massive operations could be possible along the coast, both in shallow offshore areas and on low-lying flat coastal land. But again, what would the scale have to be, and at what cost to the environment, both natural and humanised.

Yup, biodiesel from algae is one of a number of alternatives for future energy needs. But biodiesel from commercial crops gives farming some hope for the future too. Govts around the world are outsubsidising one another, as farmers go broke. The cost of food has little to do with the lousy values paid to farmers. Producing energy crops gives farmers some hope to earn a reasonable living in the future.

The best hope for farmers is that energy crops will in fact compete with food crops in the end. Look at a tonne of potatoes for instance.
They leave the farm for 200$ a tonne, they cost the consumer 18'000$ a tonne at the fast food store. The list is endless! Bring on biodiesel crops for energy use!

Taswegian, to add to you list of good suggestions:

We should strive to see that the number of people is stabilised in the first instance and that policies to convert population growth into population decrease are implemented. This whole aspect is going to be as important as reducing overall resource consumption and improving efficiencies in resource usage. We simply cannot continue to have population growth post peak-oil. It would just make no sense at all in a world where our energy sources are stretched to the limit, to continue to have a rapidly increasing number of consumers.

Let’s not forget this vital aspect of peak-oil strategy and indeed overall sustainability.

As you say; “Whatever works is likely to have a large footprint”. And it would be all the larger with more people.

I thank you all for your cautiously supportive comments. To provide some answers to the questions about economy and scale the US National Renewable Energy Laboratory made some estimates that projected costs for biodiesel which are two times higher than the 1996 petroleum diesel fuel costs.

The close down of this project coincided with the slump in oil price in the mid 1990 when petrol could be had for 60 cents a liter. However the time is now right for re-evaluating these effort since the price now is around $1.20 per liter and is not expected to go any lower for a long time. It would now be a break even proposition to produce biodiesel using algal cells.

Based on results from six years of tests run in parallel in California and Hawaii, 1,000 m2 pond systems
were built and tested in Roswell, New Mexico. The Roswell, New Mexico tests proved that outdoor ponds
could be run with extremely high efficiency of CO2 utilization. Careful control of pH and other physical
conditions for introducing CO2 into the ponds allowed greater than 90% utilization of injected CO2. The
Roswell test site successfully completed a full year of operation with reasonable control of the algal species
grown. Single day productivities reported over the course of one year were as high as 50 grams of algae
per square meter per day, a long-term target for the program.

The type of alga required would be fast growing. Natural strains of alga has been isolated that grow in saline conditions have been identified. These strains can be improved using gene technology to boost their production of oil.

To give you some example of the scale that would be required we can use Lake McLeod, just north of Carnarvon in Western Australia. This salt lake of 480, 000 hectare could theoretically be used to produce 50 million tonnes of biodiesel. The fuel consumption of the whole Australian fleet of cars , buses and trucks is 23 million tones.

Thanks for the timely numbers, Sten. The cost-volume-profit relationships for 1000m2 ponds in Hawaii are a whole order of magnitude away from 100 hectare ponds on the bed of Lake Cowan WA or Lake Torrens SA. So if Hawaii can produce diesel at $1.20/litre then there is very little doubt that broadacre farmers all over Australia can do it much cheaper and still make healthy profits.

One thing this technology will do is to finally deliver a beneficial use for all those stupid Salinity Hazzard Maps prepared by Qld Spin Central. Investors may now have a very good reason for seeking out salt loads and even mining them by, for example, pumping waste water in to extract the salt.

The other interesting issue is the CO2 injection. This would significantly alter the economics of Coal powered generation stations etc, provided they were located in places where sufficient low productivity land was available. Who knows, we may yet see a steel mill in the Pilbara, driven by a significant new competetive advantage.

I much prefer Dr. Kalla's concluding remark:

"It is an avenue that is worth exploring before our oil-based economy runs into trouble."

to his less objective comment in the middle of the article.

"However, there is a solution for Australia’s oil dependence . . . "

This is certainly a technology worth exploring, especially in Australia where we have space and climate that could be compatible with production of the algae.

I respectfully submit, though, that comments like sten's (I assume this is Dr Kalla), about Lake McLeod in WA: "This salt lake of 480, 000 hectare could theoretically be used to produce 50 million tonnes of biodiesel, " are so far over the top that they defeat the purpose of sensible debate on the issue.

Firstly, numerous breakthroughs need to be made to get 50 grams/ m2/ day the whole year round. Second, running a 0.1 hectare pond with several Ph.D’s around is nothing like running a large commercial operation for a 480,000 hectare pond. Third, nitrogen and phosphorus would certainly have to be added to the water somehow to make the algae grow. You could probably recycle N and P, but they would still be a significant input. Fourth, other energy is needed to harvest and process the algae into biodiesel, so you need to calculate the net energy result not just the tonnes of biodiesel per tonne of algae. Fifth, large ponds with algae growing in them often attract insects and other organisms that may make the operation untenable.

I hope it works, even in a small way, to help offset the imminent problems associated with fossil fuel depletion, but lets not forget the lessons of all the other ideas that have come and gone over the past 50 years. Environmentalists can’t put oil shale and carbon geosequestration under the microscope and then give biodiesel a free ride.

Finally, somebody please tell me why every half chance of an untried idea for water, energy, food etc is considered a better idea than stabilising our population?