Geo-thermal power is something we have in abundance to replace coal, why is it that people put the economy before common sense? If we don't manage to stop this freight train that is Global Warming in the next 14 years we will not have an economy. For example the $6.8 billion dollar Great Barrier Reef tourism trade will be lost people no longer have the luxury of being complacent we need action, and we need it now.

I'm amazed that there is all this discussion around peak oil and none around peak phosphorous, which is used so heavily in food production (source: http://www.energybulletin.net/33164.html).

Couple peak phosphorous with peak oil (used in the production of food and its transportation) and you have a serious problem that is going to be realised in a generation or two.

As coal is easily converted to fuel as per the Sasol plant in South Africa, I would say that peak oil is still a way off.

The greater issue is climate change. With Rudd's delegation to Bali steadfastly blocking any set reduction targets and the moritorium on nuclear, all I see for the next few decades is more of the same.

Amory Lovins from the Rocky Mountains Institute www.rmi.org has an excellent talk at http://www.ted.com/talks/view/id/51 and a book at http://www.oilendgame.com/

He outlines how the USA can wean itself off oil and benefit their economy. Australia can do the same but we are in the fortunate position of having lots of sunlight, geothermal resources, natural gas resources and are able to produce cellulose for conversion to liquids. Lovins gives a blue print for solving the issue.

Biggav: "The amount of energy available from renewable sources dwarfs that we currently obtain from fossil fuels." This is like saying that there's more gold in the sea than on the land - it's true, but there's very good reason that we don't just go and help ourselves to this vast resource of gold.

Wind, Photovoltaic Solar, Thermal Solar (without heat storage), Waves and Tides only generate electricity intermittantly, rather than when needed and have a very low capacity factor - most below 20%. Since there is no feasible way to store electricity on a large scale, these sources can't make up more than a small proportion of the total system. Furthermore, their entire full load capacity has to be provided from conventional sources because they can never be relied upon to generate when required. And Yes - there are times very little power is generated even from diverified systems.

The second problem is Energy Returned on Energy Invested. There are 2 promising technologies that produce power as it is needed: solar thermal with heat storage and hot rock geothermal. It is true that we have vast resources of these energy sources. However both of these deliver a small amount of electricity generated from a lot of heat, because very high temperature working fluids are not available, which fundementally limits the efficency of converting heat to mechanical work done. Hence absolutely huge quantities of these systems need to be deployed for a relatively small amount of power generated.

Building such a large infrastructure is not just an issue of money, it is a matter of expending vast amounts of energy to mine the minerals, smelt the steel, make the cement and so on.

Hence the electricity generated must be several times more expensive - at least 5 times by my estimation. This leads to a situation that it is impossible to continue using energy as we currently do - we have to use it much more sparingly and only for essentials like growing and delivering food if we only used renewable energy.

Yabby says: "I can crop 5% to a crop like canola, use legume based N and produce enough biodiesel to grow cereals and meat from the other 95%." This may be true for meeting your farm inputs within your fence - but I doubt even that. It certainly could only be true in a well watered fertile spot, which are in pretty short supply - this is not the majority of Australia's farm land.

Then you have to realise that people don't sit and eat at your farm. They live in cities and a large amount of additional energy is required to get the food processed and to market. This can't be changed in years or decades - it will take lifetimes.

The massive population boom over the last several lifetimes has happened because of the food made available through industrial agriculture fueled by petroleum. We currently consume around 10kJ of fossil fuel for every 1kJ of food on our plates. The impracticality of replacing this with biofuels should be clearly apparent.

So we won't. We will move to a much lower energy way of doing things and this will involve doing without a lot that we currently take for granted. Biofuels, where they are beneficial, will be used but they will never "replace oil" in anything like our current system.