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Desalination on a scale sufficient for a city requires an extraordinary amount of power. The plant in Queensland uses: "...around 3.58 kilowatt-hours (kWh) of e

Desalination on a scale sufficient for a city requires an extraordinary amount of power. The plant in Queensland uses: "...around 3.58 kilowatt-hours (kWh) of electricity for every cubic metre (kilolitre) of water it produces"[1] That's not going to be affordable for many poorer countries. It's expensive enough that Queensland only turns that plant on for emergencies. The CO2 emissions would also only intensify the problem. [1] https://en.wikipedia.org/wiki/Gold_Coast_Desalination_Plant https://en.wikipedia.org/wiki/Gold_Coast_Desalination_Plant

Retric 7y ago
That sounds much worse than it is. Outside of farming a cubic meter is a lot of water. Desalination costs ~3$ per 1,000 gallons of which around 40% is electricity costs, that’s generally affordable for most areas based on consumption and local economic conditions. Though again, not for farming.
- thaumaturgy 7y ago
  Which source are you using for that number?
  - dmurray 7y ago
    The numbers quoted for the Queensland plant referenced above would translate to about A$1.50, or US$1, for a thousand gallons. (10c/kWh for electricity according to [0]) There are running costs other than electricity, but it's always talked about as being power-intensive, so it seems fair to assume the cost of electricity dominates. $1 for a thousand gallons seems like a non issue for domestic use in developed countries. It's on par with the cheapest rates consumers currently pay in Europe, while some countries pay 8x more [1]. Even in most poor countries it should be attainable. [0]https://www.aemc.gov.au/energy-system/electricity/electricity-market/spot-and-contract-markets https://www.aemc.gov.au/energy-system/electricity/electricit... [1]https://www.thejournal.ie/water-charges-in-ireland-versus-europe-1789576-Nov2014/ https://www.thejournal.ie/water-charges-in-ireland-versus-eu...
  - Retric 7y ago
    Several sources list 3$ as the lowest all inclusive price. Though notability these systems are much more costly when run intermittently. https://www.advisian.com/en-us/global-perspectives/the-cost-of-desalination https://www.advisian.com/en-us/global-perspectives/the-cost-... The issue is just keeping them on standby is expensive. So, if you only need one for 6 months every 3 years you end up paying a lot more per m3 of water.
    - thaumaturgy 7y ago
      Hmm. That link seems to use a paper for its source, titled "Technical review and evaluation of the economics of water desalination: Current and future challenges for better water supply sustainability". I tracked down a copy of that paper. It opens with: "The cost of desalinated seawater has fallen below US$0.50/m3 for a large scale seawater reverse osmosis plant at a specific location and conditions while in other locations the cost is 50% higher (US$1.00/m3) for a similar facility. In addition to capital and operating costs, other parameters such as local incentives or subsidies may also contribute to the large difference in desalted water cost between regions and facilities. Plant suppliers and consultants have their own cost calculation methodologies, but they are confidential and provide water costs with different accuracies. The few existing costing methodologies and software packages such as WTCost© and DEEP provide an estimated cost with different accuracies and their applications are limited to specific conditions. Most of the available cost estimation tools are of the black box type, which provide few details concerning the parameters and methodologies applied for local conditions." I read through the rest of it. To the extent that it offers cost comparisons of some large scale SWRO projects, they seem to be self-reported and come from projects in Saudi Arabia, Israel, Oman, and Australia. This leads me to a couple of concerns WRT the construction and operating costs of SWRO projects: (a) that a comprehensive, independent, apples-to-apples accounting of the costs of these projects has not yet been done; (b) that some of the long-term costs are being externalized, especially the expected impacts on local ecological systems that become the necessary dumping grounds for the wastewater; (c) that the costs to date are severely location-specific, and do not address for instance trying to transport seawater a mile uphill as needed in many of the areas expected to or currently experiencing severe freshwater instability. Clearly SWRO is a viable option in specific areas that have nearby access to a suitable water source, good power infrastructure (or solar availability), a lack of freshwater availability, and an appropriate wastewater treatment strategy (or, more likely -- and sadly -- loose regulations that obviate the need to address this). But calls for SWRO as a worldwide, one-size-fits-all, cheap solution are misguided and misinformed, IMO. Mostly I worry that "just build desal" will frustrate efforts for conservation and improving existing infrastructure, especially in places where desal isn't a viable option anyway.
adventured 7y ago
> That's not going to be affordable for many poorer countries. I think that's clearly the crux of the problem with desalination. It works well right now in wealthy countries. Israel couldn't exist without it. The Carlsbad plant in San Diego can provide water for about 500,000 people and the monthly average water bill in San Diego is around 2x the national average ($80 vs $35-$40; it'd be higher if San Diego were purely desalination). $80/month in a combination water source approach is an affordable problem in high income countries, for such a valuable resource. And it's an impossible cost - even at half that price - for all but the top few percent of families in India, Egypt or Pakistan.
timerol 7y ago
Assuming $0.25/kWh (a very high electricity price), that's $0.90 per kiloliter (264 gallons). No one's going to die of dehydration at those prices, though sanitation may become expensive in poorer areas. (With the obvious public health implications...) At that price greywater reuse and low-flow everything become obviously worthwhile. It boggles my mind that the average American uses 100 gallons of water per day, but that's partially because of how cheap water is.
- AWildC182 7y ago
  Furthermore, water storage is stupid easy compared to electricity. Build out some excess capacity and then run off of cheap solar, storing the water needed for the evenings. No emissions issues, no power cost issues.
jupp0r 7y ago
> The CO2 emissions would also only intensify the problem. Good that most of the places facing droughts tend to get lots of sun. Using increasingly cheap solar power for desalination seems like a perfect fit, especially as water is easily stored and desalination plants can offset power production peaks/demand lows.

Retric 7y ago

That sounds much worse than it is. Outside of farming a cubic meter is a lot of water. Desalination costs ~3$ per 1,000 gallons of which around 40% is electricity costs, that’s generally affordable for most areas based on consumption and local economic conditions. Though again, not for farming.

thaumaturgy 7y ago
Which source are you using for that number?
- dmurray 7y ago
  The numbers quoted for the Queensland plant referenced above would translate to about A$1.50, or US$1, for a thousand gallons. (10c/kWh for electricity according to [0]) There are running costs other than electricity, but it's always talked about as being power-intensive, so it seems fair to assume the cost of electricity dominates. $1 for a thousand gallons seems like a non issue for domestic use in developed countries. It's on par with the cheapest rates consumers currently pay in Europe, while some countries pay 8x more [1]. Even in most poor countries it should be attainable. [0]https://www.aemc.gov.au/energy-system/electricity/electricity-market/spot-and-contract-markets https://www.aemc.gov.au/energy-system/electricity/electricit... [1]https://www.thejournal.ie/water-charges-in-ireland-versus-europe-1789576-Nov2014/ https://www.thejournal.ie/water-charges-in-ireland-versus-eu...
- Retric 7y ago
  Several sources list 3$ as the lowest all inclusive price. Though notability these systems are much more costly when run intermittently. https://www.advisian.com/en-us/global-perspectives/the-cost-of-desalination https://www.advisian.com/en-us/global-perspectives/the-cost-... The issue is just keeping them on standby is expensive. So, if you only need one for 6 months every 3 years you end up paying a lot more per m3 of water.
  - thaumaturgy 7y ago
    Hmm. That link seems to use a paper for its source, titled "Technical review and evaluation of the economics of water desalination: Current and future challenges for better water supply sustainability". I tracked down a copy of that paper. It opens with: "The cost of desalinated seawater has fallen below US$0.50/m3 for a large scale seawater reverse osmosis plant at a specific location and conditions while in other locations the cost is 50% higher (US$1.00/m3) for a similar facility. In addition to capital and operating costs, other parameters such as local incentives or subsidies may also contribute to the large difference in desalted water cost between regions and facilities. Plant suppliers and consultants have their own cost calculation methodologies, but they are confidential and provide water costs with different accuracies. The few existing costing methodologies and software packages such as WTCost© and DEEP provide an estimated cost with different accuracies and their applications are limited to specific conditions. Most of the available cost estimation tools are of the black box type, which provide few details concerning the parameters and methodologies applied for local conditions." I read through the rest of it. To the extent that it offers cost comparisons of some large scale SWRO projects, they seem to be self-reported and come from projects in Saudi Arabia, Israel, Oman, and Australia. This leads me to a couple of concerns WRT the construction and operating costs of SWRO projects: (a) that a comprehensive, independent, apples-to-apples accounting of the costs of these projects has not yet been done; (b) that some of the long-term costs are being externalized, especially the expected impacts on local ecological systems that become the necessary dumping grounds for the wastewater; (c) that the costs to date are severely location-specific, and do not address for instance trying to transport seawater a mile uphill as needed in many of the areas expected to or currently experiencing severe freshwater instability. Clearly SWRO is a viable option in specific areas that have nearby access to a suitable water source, good power infrastructure (or solar availability), a lack of freshwater availability, and an appropriate wastewater treatment strategy (or, more likely -- and sadly -- loose regulations that obviate the need to address this). But calls for SWRO as a worldwide, one-size-fits-all, cheap solution are misguided and misinformed, IMO. Mostly I worry that "just build desal" will frustrate efforts for conservation and improving existing infrastructure, especially in places where desal isn't a viable option anyway.

adventured 7y ago

> That's not going to be affordable for many poorer countries. I think that's clearly the crux of the problem with desalination. It works well right now in wealthy countries. Israel couldn't exist without it. The Carlsbad plant in San Diego can provide water for about 500,000 people and the monthly average water bill in San Diego is around 2x the national average ($80 vs $35-$40; it'd be higher if San Diego were purely desalination). $80/month in a combination water source approach is an affordable problem in high income countries, for such a valuable resource. And it's an impossible cost - even at half that price - for all but the top few percent of families in India, Egypt or Pakistan.

timerol 7y ago

Assuming $0.25/kWh (a very high electricity price), that's $0.90 per kiloliter (264 gallons). No one's going to die of dehydration at those prices, though sanitation may become expensive in poorer areas. (With the obvious public health implications...) At that price greywater reuse and low-flow everything become obviously worthwhile. It boggles my mind that the average American uses 100 gallons of water per day, but that's partially because of how cheap water is.

AWildC182 7y ago
Furthermore, water storage is stupid easy compared to electricity. Build out some excess capacity and then run off of cheap solar, storing the water needed for the evenings. No emissions issues, no power cost issues.

jupp0r 7y ago

> The CO2 emissions would also only intensify the problem. Good that most of the places facing droughts tend to get lots of sun. Using increasingly cheap solar power for desalination seems like a perfect fit, especially as water is easily stored and desalination plants can offset power production peaks/demand lows.