Interesting to hear of the fact that the Gold Coast Desalination plant is going with green energy. I have a few ideas myself on some options. To me it's verging on criminal that we have not yet tapped into our vast solar (and geothermal) resources. Although there is promising work being done using triple junction photo voltaic arrays in South Australia, I think that the best option is still large scale solar thermal arrays, similar to those in California.

Hydrogen:

If you produce hydrogen from electricity you never get anything approaching 100% conversion efficiency (especially using straight electrolysis), so why bother converting it? Well if you have off-peak load, it's a way of storing electricity, so Geothermal or Solar are two examples of where you'd want to store the energy in some way. 

Most hydrogen these days is separated from natural gas and steam using a reformer reaction. If you can reconvert the resulting carbon monoxide to methane using a methaniser, at least you're part of the way there. The carbon footprint is much lower than simply burning natural gas, although the calorific value of hydrogen is much lower (in volume terms) 

Alternatively, think of a Solar Power Station. The main problem with Solar is that it doesn't work too well at night. Storage is an issue. At the moment, the most efficient storage mechanism if you want to get electricity out when the sun isn't shining is an ammonia based thermochemical energy storage system. With such a system, you can have at least two possibilities:

1. A totally closed loop system.
2. A closed loop system for carbon that produces hydrogen (and consumes water)

There is actually a third possibility which I won't discuss here, as this post is starting to get complicated enough as it is. All three are carbon neutral. In design 1 , the ammonia is dissociated to nitrogen and hydrogen using solar-thermal energy. The gases are then recombined catalytically at high pressure and temperature to recover the energy. The energy is used to drive a turbo-generator.

Design 2 uses a steam Reformer (inputs methane, steam and air) to produce excess hydrogen. The nitrogen is separated from the air (using Pressure Swing Absorption). Pressure Swing Absorption is also used to purify the hydrogen. The hydrogen and nitrogen are combined, and the excess hydrogen is used for automotive use. The resultant carbon monoxide is reacted with steam in a methaniser (another catalyst) to produce methane. The methane is recycled back into the Reformer. The ammonia is dissociated using solar-thermal energy.

I won't go into design 3, but the products are hydrogen, ammonia and energy.

The bottom line is that this is all proven technology.

By the way, if anyone still has doubts about anthropogenic global warming, I'd love to talk through the issues. I have a reasonable working familiarity with the chemistry, climate modelling and atmospheric physics, so you can make it as technical as you want.

We can duel with Rayleigh Absorption scattering equations at 20 paces if you so desire 

Climate models of today are considerably more accurate than those of the early 80's, but the interesting thing is that using some of the earliest models, we can predict what has happened over the last 20 years or so - with no iteration involved. Long term climate is largely deterministic, whereas short-term weather is stochastic. 

There are some natural influences of course, and the biggest errors are related to polar effects, aerosols and cloud albedo modelling. There are also cyclical effects such the Southern Oscillation Index and the effects of large explosive volcanoes, such as Mt Pinatabo. La Nina episodes such as the one we are currently experiencing generally have a short-term global cooling effect, as do explosive volcanoes.

- but the biggest single factor that we can't model is the response of mankind. How quickly can we curb emissions and develop alternative energy sources? The latest IPCC synthesis reports provides us with a range of possible scenarios.

In another thread, it was mentioned that South Australia could become the Saudi Arabia of Australia. Here's a major contribution that SA is currently making to the field of renewable energy.

http://www.greenandgoldenergy.com.au/

The suncube is a triple junction photovoltaic panel which uses a solar-tracking concentrator to maximise efficiency. They have achieved a peak energy efficiency conversion of just over 40% (typically >35%) with a measured output of 750 Watts per square metre in Adelaide. Suncube was launched at the Green City Festival in Adelaide about four weeks ago.

Triple junction cells are much more efficient than conventional solar panels. Up until now, they have been reserved for space probes, such as the NASA Mars Exploration Rovers Spirit and Opportunity.

As far as cost is concerned, energy production using this technology is currently about the same level of cost as natural gas fueled energy production.

In another thread, it was mentioned that South Australia could become the Saudi Arabia of Australia.

Umm that analogy is so far off the mark that it borders beyond ridiculous

Sprintcyclist wrote on Mar 21^st, 2008 at 11:01pm:


Conventional Solar Panels have the disadvantage that the total energy derived from them over their life cycle is typically less than the energy (mainly fossil fuel derived)  taken to manufacture them. That is not the case with TJ cells.

If we can develop cellulosic ethanol and biodiesel production facilities using otherwise unused (semi-arid) land, then at least we'll be part of the way towards supplying automotive fuel needs. Then we have enormous solar and geothermal reserves. Find a way of storing that electricity in chemical form, and we could easily be exporting energy. 

One of the new renewable technologies will probably dominate eventually due to market factors, but in the short term, we're going to have a mixture of energy sources.

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Seems a shame we aren't using it for power generation.

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Where is the water going to come from?

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Why's that? With around 1% of the World's CO2 emissions it will make no tangible difference to the World's emissions if Australia goes nuclear or not.

freediver wrote on Mar 22^nd, 2008 at 6:00pm:



Its not meaningless at all. Were talking about a country, ie a political and economic entity. Something like a decision to go nuclear will require a government decision - so there you go, there is a line around our population of 20 million.

We might do more developing and exporting clean coal technologies in any case - given that we are a significant coal exporter.