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There is no waste. The only inputs are water, CO2, and electricity. The only outputs are fuel and oxygen.
by rmcginnis 7y ago
There is no waste. The only inputs are water, CO2, and electricity. The only outputs are fuel and oxygen.
- bencollier49 7y agoWhat about the device itself, its lifetime, and the resources used to build it?
- rmcginnis 7y agoWe expect a long lifetime (approx. 20 years or more), assuming modest maintenance costs. The capital is actually pretty inexpensive for a room temperature, unpressurized, electricity only system, so this helps mitigate longevity risks.
- ineedasername 7y agoWith respect, that answer skirts the question of what happens to the water. You said you're using the nanotube membrane to separate petro products from the water. What do you do with the water left over? What state is the water in when the process is complete? Potable? In need of treatment by traditional water treatment facilities?
- icebraining 7y agoIf water is an input and not an output, that implies it's consumed, not left over.
- ineedasername 7y agoI would think so, but the founder says: we have a carbon nanotube membrane that replaces it [distillation], extracting the alcohols from water This implies there is still water there. Maybe it was poor phrasing, and all of the water is consumed, but that isn't what is stated.
- penagwin 7y agoI think the water that is still there after distillation will just be used for more distillation, it just hasn't been consumed yet, it isn't a waste product.
- eanzenberg 7y agoYes, one of the things that gets glossed over many times in this field (I used to do research in artificial photosynthesis) is that water gets consumed to create the fuel, and is released as vapor from every engine's exhaust. So to generate 10 million barrels requires about 10 millions barrels of pure water, per day, to satiate the US.
- rmcginnis 7y agoYes, water is turned into fuel and oxygen. In most places the water can be obtained from moisture in the air (there is much more water than CO2 in air, and we are already mining the air, so we can get both). In the process the fuel is separated from the water, which remains in the reactor, and is topped off as it is used to make the fuel. No waste water.
- skykooler 7y agoThe water becomes the fuel. The hydrogen combines with the carbon in CO2 to form hydrocarbons, while the oxygen combines with itself to form molecular oxygen.
- ineedasername 7y agoI would think so, but the founder says: we have a carbon nanotube membrane that replaces it, extracting the alcohols from water This implies there is still water there. Maybe it was poor phrasing, and all of the water is consumed, but that isn't what is stated.
- zdragnar 7y agoIf the inputs are truly CO2 and electricity, and 100% gets converted to usable hydrocarbons, then there's no waste water; the catalyst and water remain behind. Assuming some water is lost due to electrolysis, you can top it off over time. If the catalyst breaks down, or some undesired reaction limits efficiency (i.e. generation of perioxide or other undesired chemicals that degrade or react with the membrane, electrodes, catalyst, etc) then I think there might be some treatment or maintenance necessary. However, none of this sounds remotely as bad as the treatment needed in the production of petrochemicals or lithium batteries or recycling.
- mikorym 7y agoThere is no water left either—you forgot that oxygen is also produced.
- zdragnar 7y agoI wasn't really sure how much of the o2 generated came from the co2 and how much came from the water. Either way, I don't see "waste water" to be as big an issue as the earlier posts i was replying to did.
- geofft 7y agoI think you're asking a different question from the one being responded to (and the one being responded to is more obvious to me): I will try to help this conversation by restating the questions, both of you should correct me if I've misread this. Your question is, in the distillation step, the nanotube membrane separates fuel from water, leaving some amount of water; what happens to that water in the process? The question that was answered was, what happens to waste water? For which the answer is that there is no water "left over", and so the question of what happens to it is ill-defined because it doesn't exist. So I guess what is happening is that any water left in the aqueous electrolyte can continue to be used in the process indefinitely, and there is no point at which the water becomes waste water? That all the water collected from the air gets broken up into hydrogen (in the fuel) and oxygen (waste product, sent into the atmosphere) and the amount of water in the aqueous electrolyte doesn't grow?
- rmcginnis 7y agoCorrect!
- ineedasername 7y agoThanks for confirming, though what if the ingested air/vapor/carbon mixture has a consistently higher than required water-vapor/co2 ratio? Or is that a non-issue?
- deleted 7y ago[deleted]
- __d 7y agoWhat about dust, pollens, etc, from the air? Is there a maintenance requirement to clean filters or something? Does the efficiency of ingesting the water vapour and CO2 decrease over time until maintenance is performed?
- rmcginnis 7y agoWe'll want to filter our air, yes. This means replacing filters, etc, which factors into the maintenance costs.