The headline, while accurate, doesn't really describe the breakthrough here.
In itself, it's not surprising that sunlight, hydrogen from water and CO2 could be put together to make biomass. That's pretty much what plants (and many natural bacteria) do already.
The novel aspect of these bacteria is that they apparently do the job 10x more efficiently than natural organisms.
It's 10x more efficient for human purposes. It's not a 10x more efficient mechanism in general. Evolution has no need to produce 10x more rather energy-expensive molecules than it needs, so it doesn't produce bacteria that do that.
Which is also the answer to everybody else wondering about what happens if this gets into the biosphere. Well, have you ever been walking in a relatively natural forest area and come across the sad sight of a natural clearing being totally dominated by wild broccoli plants? No, you never have, because broccoli is completely incapable of outcompeting any natural plant. Broccoli's genes put way too much energy into producing that big beautiful edible bit that all of its competition puts into offense and defense. Similarly, the answer to the question of what happens to bacteria that pours its energy into producing alcohol while its competition is pouring its energy into producing offspring is that if you blink, you'll miss the death of the alcohol-producing bacteria. They're not going to take over the ecosystem. In energy terms you probably stand a better chance of seeing broccoli sweep the meadows of the world than having this bacteria survive in the wild.
(And when I say broccoli, I mean something like what you'd buy in the store. Not merely a rapid reversion to its historical ancestor, which could actually happen, but actual proper broccoli.)
> Evolution has no need to produce 10x more rather energy-expensive molecules than it needs, so it doesn't produce bacteria that do that.
You don't seem to understand natural selection. The idea of evolution producing something that an organism "needs" is akin to saying that God decided that the organism "needed" it and changed its genes.
The theory of natural selection is a completely passive process. For every generation of an organism, the genes are naturally randomized, producing various expressions of genes, and once there is selecting event, those that are not selected for will go extinct. That's what natural selection means. The idea that a giraffe "needed" a long neck is preposterous because it implies that the animal willed itself to have a longer neck. Instead, the giraffe's ancestors had a variable length neck, but given its particular circumstances, those with longer necks survived, and passed those genes on.
So there very well might be naturally occurring bacteria that produce 10x efficiently, but they haven't been selected for, yet.
> You don't seem to understand natural selection. The idea of evolution producing something that an organism "needs" is akin to saying that God decided that the organism "needed" it and changed its genes.
I'm pretty sure he understands it fine, and is just using shorthand that makes it easier to describe.
There exists no approximation of a fitness function in nature that selects for this output because it's not efficient for survival, until we come along and create custom environments and select for survival based on energy output.
I can't decide which I find more annoying; The grandparent's misuse of terms, or the people pointing out that 'that's not how evolution works, it doesn't go towards anything, just away from what doesn't work.' I'm sure plenty of people don't get it, but it's really, really, really convenient shorthand for "Selective pressure has thus far favored" to say that "Evolution wants" or "Evolution needs". It's simple, it's unambiguous, and it's often backed up by our own human perceptions - Most of our wants and needs are based on selective pressure, so generalizing that to other selective pressures as 'wants' and 'needs' is a very natural abstraction.
(I've decided which is the most annoying: Meta-pedants like me.)
I've learned the hard way that using the klunky English required to be "correct" in an otherwise two-paragraph reply just isn't worth the time. If I were writing a scientific paper I'd be more careful, but HN comments don't benefit from the bloat.
I suppose I could #include<evolution_isnt_anthropomorphic> up front and then carry on.
Because those species are sinking the extra resources into out-competing the local flora a/o fauna, and successfully displacing them. That's kinda a definitional characteristic of an "invasive species".
Small nitpick, but you can have a 'single fitness function' represent an entire environment. That's the entire concept of a fitness function: to simplify the merit of solution within an complex environment (or set of constraints/inputs/etc.) into a single figure. Obviously nature has a much complex fitness function than the efficiency of this one CO2 process. I think its more correct to say a "simpler fitness function".
Actually, there is only one evolutionary fitness function, and that is reproductive fitness. The environment is the only variable. If your environment contains an intelligent agent that values the production of (say) alcohol, and the power to influence the selection of alcohol-producting organisms then an organism that produces alcohol can thrive. But this is true of anything, not just alcohol. Substitute "kitten photos" (or anything else) for "alcohol" and you will still have a true statement.
Evolution isn't designed, but it also isn't random. It's just directed by survival, which isn't always best served by maximum efficiency in specific functions like this one.
Evolutionary changes occur by random mutation and, in sexual reproduction, by random genetic mixing. Whether or not those changes are successful is governed by survival, but it's not directed by survival. Survival doesn't choose specific evolutionary changes with a goal of increasing survivability.
This has become a completely semantic argument, but HN is a great place to argue semantics, so here we go.
> Evolutionary changes occur by random mutation and, in sexual reproduction, by random genetic mixing
The genetic changes of evolution are due to random mutation, but the ones that don't survive are not "evolution". Evolution is the subset of random mutations that increase reproduction/survival rates. If, at some point, a chimp was born with two heads, we wouldn't say that "chimps evolved to have two heads" because that two-headed chimp didn't pass on its genes. We'd say "a chimp randomly had two heads one time" and wouldn't bring it up in a discussion of evolution at all.
> governed by survival, but it's not directed by survival
To be directed by something does not always imply intentionality. Of course the most common usage of "direct" indicates something intentional, but that wasn't how I meant it. I meant "direct" in the sense that a particular landscape will direct the course of a river.
I think what he meant was that each individual mutation is random. There isn't someone intelligently deciding what the next batch of mutations should look like.
My understanding of evolution was that it wouldn't necessarily give you the best possible set of "features", only ones that aren't disadvantageous enough to put you out of the race.
Not strict enough. Genes are the subject of biological evolution, including human genes. But ideas are memes, and are subject of cultural evolution. These are two very different evolutions.
It probably was found. The damned thing just outcompeted (aka killed off) all the other organisms around it, then died off when there was no longer a working ecosystem to provide for some critical resource or to dispose its waste. Centuries later, invasive species from far away took over the wasteland and started over again.
The headline is seriously misleading, the energy comes from sunlight which is used to split water into hydrogen. And the bacteria use the hydrogen as an energy source to create biomass from CO2. That biomass is mostly in burnable fuel.
The article is very interesting, but the headline makes it sound like a fundamental misunderstanding of thermodynamics.
I think it's more a difference between technical vocabulary and colloquial vocabulary. I think a lot of people use the word "energy" to to refer to something more like "fuel." That's how you get terms like "energy production" which include activities like drilling for oil.
“This isn’t solving your CO2 problem,” he said. ”I’m taking CO2 out of the air, you burn it and you put the CO2 back. So it’s carbon neutral. I’m not going to reverse 400 ppm of CO2. But you’re not going to use any more stuff out of the ground.”
I think he's selling it short. Imagine if all 1 billion+ cars used this fuel instead of diesel/gasoline. Even if all the carbon ultimately ends up as CO2 again eventually, at any given moment there would be a whole lot of it temporarily sequestered in fuel tanks. The "base load" of atmospheric CO2 would be lower.
I don't know enough chemistry or climate science to estimate whether the amount of carbon in ~5 billion gallons of alcohol-based fuel, when removed from the atmosphere, would have a significant effect on climate change. But it sure seems like a lot of carbon.
Given that the current level of CO2 in the atmosphere includes the output of over 100 years of industrial world-wide burning of petroleum and coal, then no I don't think the amonut of carbon that could be sequestered in current fuel inventories would make a significant difference. Unless you stockpile decades worth of fuel.
Yeah, but it's a hundred years of industrial burn which was growing at an (approximately) exponential rate; the most recent burn has a much, much larger impact than the burn in 1916.
"The leaf hasn’t lived up to its promise, Nocera said, because the world isn’t ready for hydrogen fuel."
And probably won't be for transportation because battery tech is improving. But if this proves to be an effective way to produce liquid biofuel that can replace gasoline/diesel with simple engine conversions, then we can repurpose our existing liquid fuel infrastructure and existing cars instead of building a whole new hydrogen based system.
It's the smallest molecule there is. It's really difficult to contain. It will leak out of steel containers while embrittling the metal. However it's not necessary to use pure hydrogen as vehicle fuel. Alcohol or other hydrocarbons can be used directly in a fuel cell to produce electric power, or be burned in an more traditional combustion engine.
Hydrogen leaks out of steel containers because it's "small"? Doesn't the size of even the largest atom (or, for that matter, molecule) pale in comparison to even the smallest leaks you will typically find in a steel container?
The thing that made the Hindenburg transformative is that it was caught on film. After everyone had seen the disaster for themselves, they were never going to trust the technology again.
My brilliant invention: A solar powered self replicating machine that eats CO2 and uses it to create building material. With minimal preparation the material could also be burned for energy.
I wonder how far I'd get before people realized I was planting trees.
Any mechanism to capture CO2 emissions is a huge win for the environment.
What is missing is an assessment of cost. If this is economically feasible at some point in time in the future, then goodbye oil and coal.
Open question is how to ensure these bio-engineered organisms don't seep into the environment and trigger some unintended consequences. There needs to be some kill switch in there as well.
They die. The bacteria are dependent on a constant stream of hydrogen gas at higher concentration than typically found on earth. They simply cannot compete with any other organism outside of the reactor for which they are designed.
Scenario: Mixing in the chamber isn't complete, after a few generations, bacteria that can survive in a low H environment continue to breed. Worker forgets to purchase reactor before maintenance, bacteria escapes. Hilarity ensues.
Are there not hydrogen rich microzones (volcanic fissues? atmospheric layers?) where these might thrive?
I'm not actually worried about bugs taking over the world. But we ought to avoid hand-waving away possible unintended consequences, because that tends to be how we get ourselves into environmental problems in the first place.
While there are certainly conditions in which these bacteria might thrive, their inbuilt inefficiency -- secreting large quantities of energy-rich alcohol -- suggests that, in their current form, they'd be relatively easy to outcompete. They don't seem to have any particular advantage in an environment where their unique characteristics are not beneficial -- and very few environments would seem to fit that bill.
That's like worrying about cattle getting loose and taking over Africa. The same things that make them useful to us also make them horrible at competing in a natural setting.
So yes, it provides a little bit of power, and no, it isn't likely to scale up to planet-wide CO2 reductions - one per person on the planet just to cover the CO2 we breathe?
It sure sounds promising, but it'd be good to see some more efficiency numbers. All there is in the article is this:
"A one-liter reactor full of Nocera’s bacteria can capture 500 liters of atmospheric CO2 per day, he said. For every kilowatt hour of energy they produce, they’ll remove 237 liters of CO2 from the air."
By my reckoning that works out to about 80 watts, continuous. Solar irradiance is roughly a kilowatt per square meter, so to get 80 watts at 10% efficiency you need nearly a square meter, which leaves your 1-liter reactor stretched to a millimeter thick. Hard to imagine a 1mm thick mat of bacteria absorbing 10% of the light.
The limiting factor really is area, not volume. By that metric, solar panels are still twice as efficient. Still, it would be good to have solar panels that grow themselves!
I wonder how much of the efficiency increase comes from simply bypassing photosynthesis (e.g. what is the thermodynamic efficiency of yeast for glucose -> ethanol)?
In any case there are a few important questions re feasibility. Do these bacteria work at atmospheric partial pressures of CO2? Do they perform at the advertised rate at the ~0.0015g/L of hydrogen you'd be lucky to get in solution from his leaf?
Nocera is a blow hard, so pending the full paper I expect the answers aren't encouraging.
Yay. Now we don't need plants to reduce the greenhouse gas CO2. We just need to turn loose this bacterium and build an economy around alcohol fuels. No need for systems thinking that involves the environment when we can create a bacterium which is more efficient in one aspect of the environment it is replacing. So long as we can extend this reductionist framework to provide us with the nitrogen we need. And the global temperature management functions. And the human food. And the....etc
Agreed, though I kind of like the idea of replacing carbon positive fuel with carbon neutral fuel. If we overproduced fuel--thus sequestering carbon--we could go some way toward cleaning up at least some of our carbon mess. That would reduce some of the anthropogenic stresses on ecosystems rather than allowing them to collapse. We need to get our shit together with respect to the environment, but if we can stave off catastrophe for a while, I think we're in better shape.
It's unlikely we wouldn't consume it, but we could "consume" it without releasing the CO2 into the atmosphere, e.g. by making polyethylene from the alcohol.
The application you've described isn't depressing.
Carbon dioxide is a normal element in our atmosphere. Burning biofuels isn't a problem because the world's ecosystem is used to processing the levels of carbon dioxide that exist in current circulation.
The problems that come from carbon dioxide in the atmosphere happen when you alter the levels of carbon dioxide faster than the ecosystem can react. This happens when burning fossil fuels on a large scale because it leads to adding more carbon dioxide into standard circulation. As there isn't a proportional increase in plant life ready to absorb this increase the carbon dioxide can have negative impacts on our environment, such as ocean acidification.
Not depressing at all. If we can continue to generate energy to meet our current level of demand without introducing more CO2 into the atmosphere than was there before then our climate crisis is solved.
Human energy use will have a zero net effect on CO2 levels, meanwhile, the oceans and rocks and the world's flora will gradually bring the concentration back down to a more desirable level.
The biosystem can handle almost any amount of fuel-burning and release of CO2 from fuels that came from the biosystem. In that regard, burning is like recycling.
The problem is that we pump CO2 from outside the biosphere (from deep underground) into the biosphere.
This technology could eliminate the need to move CO2 from underground into the biosphere, without having to completely revamp our existing infrastructure. If this is possible, it would be a gigantic win for the environment.
Very cool, except first you need to get the hydrogen. For that I believe he is planning to use the "artificial leaf" he has invented previously.
Problem is, while the bacteria can reproduce on their own, the leafs won't. They are made from silicon so probably similar tech to regular solar cells. This can be likely a limiting factor here.
I can't open the forbes page; how does this compare to Nate Lewis' work at cal tech (which is a mechanical alternative): http://nsl.caltech.edu/research
Everyday I think of the suffocating levels of pollution here in India while I commute. This is a fantastic news for us since they are planning to bring it up here first !
When Harvard Professor of Energy Daniel G. Nocera announced he was working with bacteria last year, other scientists cautioned it would be difficult to achieve a productive level of efficiency. At the time, Nocera was aiming for 5 percent efficiency—about 5 times better than plants. This month at the University of Chicago, he announced his bug converts sunlight ten times more efficiently than plants.
This increase in efficiency is presumably the novel part of Nocera's latest announcement and upcoming paper.
In itself, it's not surprising that sunlight, hydrogen from water and CO2 could be put together to make biomass. That's pretty much what plants (and many natural bacteria) do already.
The novel aspect of these bacteria is that they apparently do the job 10x more efficiently than natural organisms.