On 13/07/2009, at 11:39 PM, John Williams wrote:
If it takes a lot of energy to condense the water, then you need a large wind-turbine or a lot of solar panels.
Depends how much water you need.
And how much energy does it take to manufacture the wind-turbines or solar panels?
Depends on the answer above.
Would it have been more efficient to run a large-scale desalination plant somewhere else (perhaps with nuclear power?) and pipe the water to the needed location?
Depends on how far you need to pipe it and to how many people.
These are not rhetorical questions. I'd be interested in the answers if anyone knows them.
Yep. Well, here's the situation at a place I've been - the roadhouse near the entrance to the Shark Bay World Heritage area. There are 6 permanent residents, 3 or 4 transient staff, and on any night there may be 30 or so visitors, mostly in caravans/campervans, a handful in the cabins of which there were 4 iirc. Probably 50 - 60 trucks a day go by. Some showers. A radio transmitter (booster station). Cafe in the roadhouse. This place is about 100 miles in each direction from the next similar roadhouse (doing this from memory, can't be arsed to find my journal). Water is bore water, and drinking water is provided by reverse osmosis powered by diesel generators. So, a couple of wind units producing 10l/hr (5001/day, roughly - plenty for drinking and cooking, at least) each of potable water would go a long way towards lowering the cost (energetic and fiscal) of producing drinking water. And piping water, at present, makes little sense.
However, if the main water pipeline is built taking good quality water from the north at Lake Argyll or a similar dam project down to Perth is built, then suddenly branch pipes to towns and maybe along the main highway suddenly makes sense.
Likewise, the energy, construction and piping costs of bringing water from a desal plant planned near-ish to Melbourne don't make sense compared to beefing up the water reclamation plant and using recycled water for the power station that currently uses 100 gigalitres a year of potable water (freeing up 100 gigalitres for drinking, which is what the desal plant is going to produce *facehand*), or even piping water across Bass Strait from where there is lots and lots (Tasmania) to where there isn't (Victoria).
I guess that's a long-winded way of saying - need to look at every case on its own merits, which I guess is probably where you were headed too?
Charlie. _______________________________________________ http://mccmedia.com/mailman/listinfo/brin-l_mccmedia.com
