Our waterways are becoming more and more polluted due to PFAS, plastics, medicines, drugs, and new chemicals made by companies that just hand over the responsibility of cleaning to plants paid for by public moneys. Detecting the different chemicals and filtering them out if getting harder and harder. Could the simple solution of heating up past a point where even PFAS/forever chemicals decomposes (400C for PFAS, 500C to be more sure about other stuff) be alright?
Raising water temperature from 10 to 500 degrees requires about 500 calories/mm3. That’s 2 MJ/litre, meaning if you want to heat 1 liter/second you need 2 MW with perfect insulation, so a power plant of say 10 MW.
A post industrial world citizen could probably get by on 200 l/day (US averages about 300/day). That needs 2 kW/person/day.
Total global energy production is about 630 EJ which averages out at about 12 TW.
Meaning if the whole global energy production went to treat water in that way, we have enough clean water for about 6 million people.
How the hell do people use that much water? Are they including water consumption needed for the products we use or? Let’s say a flush is 8L and the average person flushes 5 times a day, that’s 40L. The average person needs about 2L of water a day. Let’s say an average shower is 100L. Cleaning dishes at worst is probably like 20L per person without a dishwasher. That’s like 160L of water per day and I feel like most of those were over-estimates. How did they get to that number?
They eat meat.
Yeah but it says “at home” and gives recommendations how you personally can reduce water consumption (like more efficient taps or showerheads), which makes me believe that it’s not your entire direct and indirect water consumption (which realistically isn’t even relevant for the argument since the water used for crops isn’t gonna be getting treated anyway)
The estimations for water required to make meat even include rainwater. As if cows are out standing in the field collecting water through their hooves or something.
They use AI.
How much water do you believe AI consumes? The 31 billion land animals we keep in captivity and the crops we grow to feed them dwarf most human water consumption.
https://oecd.ai/en/wonk/how-much-water-does-ai-consume
https://www.forbes.com/sites/cindygordon/2024/02/25/ai-is-accelerating-the-loss-of-our-scarcest-natural-resource-water/
That’s a lot, but by some back of the envelope math I calculated that American consumption of cheese alone uses four times that amount in a year.
Based on this, 4 oz of cheese uses 450 liters of water. https://foodprint.org/blog/dairy-water-footprint/
Based on this, the average American consumes 41 lbs of cheese per year. Each lb of cheese uses 1800 liters of water per the above. https://www.statista.com/statistics/183785/per-capita-consumption-of-cheese-in-the-us-since-2000/
That means that each US citizen uses 73,800 liters of water per year on cheese alone.
Multiply that by 340E6, the US population, you get 25 trillion liters of water per year. That’s 25 billion cubic meters of water a year.
Not that AI is environmentally friendly by any stretch, but dairy is the equivalent of like, a dozen AI industries all stacked on top of each other. Feel free to check my math and correct me as needed.
Yes, with our current energy output it would not be possible, but I’m asking about whether even theoretically it could be an easier way to clean water. Maybe in 10, 20, 50 or 100 years it’s a method worth pursuing.
This is simple math. We would need to increase our energy production by 1000 times to just treat water, maybe only 250 times if we used more efficient systems than simply heating it and letting the heat dissipate. If we doubled our energy production every year, it would still take a decade to do it (8 years if we were aiming at 250 times). That isn’t a realistic amount for a civilization at our tech level.
You say 1000, another poster says 11, and yet another gives another number I can’t remember.
If I’m reading the graph right on page 20 of Homo Sapiens’ Energy Dependence and Use Throughout Human History and Evolution, in 1820 we needed about 20 EJ. That’s a 31 fold increase to ~530 EJ in 2010 (190 years). Looking at the chart, you can see that the rate of increase has sped up, not slowed down. In 1960 it was ~120 EJ making it a 4x increase in years.
It might take time, but it’s not impossible. And unless a great calamity happens upon us, we will not stay at our current tech level for another 200 years.
I understand the pessimism, but my question wasn’t about “is this possible within our lifetimes” or “how much energy would this need” but “Could wastewater plants simply heat up water past 500C to decompose all chemicals and output clean water?”. I just want to know if with our understanding the water will be clean after going through a procedure where it’s heated past 500C. That could be once or multiple times, it could involve adding a filter, removing deposited waste material, etc.
The part you’re studiously ignoring is plenty of people saying yes, you could do this, but that it’s wildly inefficient. You could also power a bike by getting the biggest rock you could throw, tying a rope to it, applying the brakes on your bike, throwing the rock, releasing the brakes, and then pulling on the rope until you’ve collected your rock, and repeating until you’ve reached your destination. This will always work. But as long as your bike is in earthlike conditions, there will always be easier ways to do it. This is also the case for your idea.
You’re ignoring that I’m responding to the messages that say it’s wildly inefficient by saying things can change. Nowhere am I debating it’s not inefficient. You’re arguing with a strawman you built.
If by strawman, you mean fundamental laws of physics, then yes, you’re correct. If we find ways to break basic laws of thermodynamics, then I won’t be worrying about ways to sterilize water, I’ll be worrying about how to make faster-than-light starship.