Mr Windy, (Continued),

One potential I see is for aquaculture based on a phytoplankton base - marine and/or fresh water. (Where all the necessary fertiliser is going to come from is the stumbling block.) My concept is however, to use solar from a massive inland solar concentrator, with greenhouses under the mirrors, and solar desalinator (using saltwater pumped from the coast when necessary to top-up - and possibly as a means of providing fresh water to an inland or coastal city, or both), and fully climate controlled - a sort of desert country recovery plan, and maybe inland city.

Solar may not be as limited as you think. Solarinvest in Qld will install a semi-professional 60,000kwh/yr solar for $180,000, which is supposed to return around $24,000/yr from grid inputs, net, after average household use. It's not a very big setup either. Though, with state govs manipulating input credits, the maths might be risky, but output is approx 8x average household.

Bottom line: For say 70% current average Western lifestyle to be maintained great energy use efficiencies will have to be achieved in homes, business and industry, biodiesel and electric machinery as standard, large solar, geothermal etc established, and coal still burned with its emissions balanced by increased photosynthesis. Oil I think in due course will be reserved for plastics, chemicals, etc manufacture which can't be achieved using other materials.

Nonetheless, we will probably have to go nuclear eventually in the first world - with thorium being preferable to uranium, but the greatest potential must lie in Africa and South America - for food and biodiesel at least, and using heaps of manual and livestock labour, with biomass local electricity supply, and TV, Internet, fridges, air-con, all the goodies, and biodiesel cars/trucks/trains.

Of course, world population will inevitably have to reduce, but I don't see us all going back on the farm.

Saltpetre it all sounds great on a small scale.

But I really don't think you comprehend the problem of massive scale with all these alterantives you have suggested.

They won't yield enough energy to sustain our current global population at current energy consumption levels. Or we will simply lack the resources and energy to implement and maintain them on the required scale. Particularly when oil becomes scarce and uneconomic.

Perhaps you should look at this website: www.solarbythewatt.com/2009/03/05/can-solar-replace-fossil-fuels/

It might give you some comprehension of the problem of massive scale.

"For our calculations we will assume installation / construction cost for one 1MW of $5m. This is a number ($5/Wp) we think smaller than the recent historic numbers for cost to install solar capacity. But we want to factor for future falling prices of solar modules and other components and overall improving efficiency in the industry. Anyone is free to factor the $ numbers we have if they believe $7/Wp or $10Wp is a better number.

For surface area needs we will assume 200 kW per acre. With different design and technology 800kW per acre is possible but we will go with the low number on this to be on the safe side. Since 1 sq mile is 640 acres, with our assumption we will have 128 MW per sq mile."

Total Energy Consumption in the World not just Electricity: 16,000GW

To replace entirely with solar photovoltaics: $80,000 billion

Will require 125,000 sq miles of solar voltaics

An area the size of Norway, Malaysia, Finland, Germany, a bit less than Japan, a bit more than New Mexico or simply area 350×350 miles

Mr Windy,

A rethink on solar potential, and 125,000 square miles is not such a big ask, for Oz anyway. At 350x350 miles we could fit a heap of them in central Oz, so, we'd be laughing. Ok, the cost is enormous, and Oz certainly couldn't afford anything like $80 trillion dollars, but is this to supply whole world need, or just Oz? I can't see us exporting electricity to the world, but could excess production perhaps be converted to another energy form which could be easily transported? Like, say, reconstituted carbon dioxide into pelletised coal? If so, a rail line would be a boon to an inland city, and the capital could be justified by such an export.

As for logistics, a super solar concentrator facility could sustain a fair inland city, providing manpower for a huge greenhouse industry, and it's not beyond imagination for transmission of water to/from and electricity from such a facility to support a substantial coastal city as well.

Now that we see Germany closing down a number of nuclear plants, and planning to close all? by 2022? I wonder what's going to replace them?

350 miles = 563 km, x = 317,275 square km = 31.73 million Ha.

Area of Oz = 7,617,930 square kilometres, (2,941,300 sq miles) = 761.793 million Hectares = 24 solar cities worth.

Japan apparently has 27,820 km² under irrigation, of a total land mass of 374,744 km². So, they couldn't have a super solar, and will have to do something else - like burn coal and gas, + nuclear. Many others will be in the same boat.

If it were possible to convert solar energy to a concentrated easily transportable energy form, Oz could potentially be the saviour of the world (as more nuclear is shut down and gas supply runs down), and if global warming is proven to be real and a threat, the world could conceivably pay for Oz to become Solar Central.

Aquaculture capturing CO2 = food; then convert excess to biomass = export? (As previously, primary nutrient is the key.)

Just a thought.

Saltpetre I think you are dismissing and area of solar voltaics the size of Norway as doable in Australia from the small scale universe of your house and life.

I just don't think you have ANY real comprehension of the technical and logistical difficulties involved in such a massive scheme.Or how impossible such a task would be without cheap oil derived energy and industrial power that it provides.

Remember that in the end we would have to maintain this Norway sized area without petrol and diesel, without heavy haul trucks and cranes etc.

It is not a simple matter of constructing this thing and then just sitting back reaping the benefits as you could a solar panel on your roof for 20 years or so.

For starters dust would continually settle on the solar arrays and have to be cleaned off so as to avoid effeciency loss. It is an easy matter of cleaning the solar panels on your roof (by stepping out your door and climbing a ladder), but imagine the enormous logististical task of doing this over an area the size of Norway in the out back hundreds or thousands of kilometres from city resources and man power.

Dust and rain would eventually scratch and pit the glass surface of the solar arrays which would have to be replaced periodically. Easy to do with a the array on your roof. But again consider even finding those solar arrays that need their glass case replaced in an area the size of Norway.

There is sensible optimism Saltpetre and then there is delusional optimism. And optimism over such a scheme is definitely the latter.

I am also optimistic that renewable energy can solve our energy problems in the future. But I re-iterate it will have to be combined with substantial global population reduction to be remotely practical.