What is the yield?
Thanks,
Rob
I’m not sure of the specifics, but you’ll certainly have something with a lot of carbon in some form, whether it be other hydrocarbons, CO2 (using up oxygen,) or carbonate compounds.
I am not sure how this is done, or, indeed, why, but petroleum consists almost exclusively of hydrogen and carbon, so ideally the by-product would be carbon, but in practice I should guess most likely carbon dioxide, with the process consuming a good deal of oxygen.
Frankly, if you have petroleum and want to make hydrogen, I should think you would be better off using your petroleum to run a generator, then using the electricity to electrolyze water: by-products then will be CO2 and water vapor (from burning the petroleum) and oxygen from the electrolysis, which would probably be quite valuable in itself.
The idea is to produce hydrogen without producing CO2.
That’s a rather tall order from oil. I guess you may be able to drive off some hydrogen and make the oil heavier, in theory you should be able to have basically hydrogen and coal produced but if you burn the coal the CO2 gets out.
Natural gas to H2 would be a better conversion, and perhaps more plentiful then oil, with far less carbon to become CO2, and IIRC some at home fuel cells do this (make power from the fuel cells and burn the remaining products for heat)
Whose idea? The only methods I know of produce CO[sub]2[/sub]. If you know of other methods, why ask what their byproducts are? If you don’t know of other methods, why do you think they exist?
My idea. I wanted to know if it can be done, but apparently not. So, what about natural gas? What are the products of natural gas to H2 conversion?
Thanks,
Rob
CO[sub]2[/sub]
Yes Natural Gas does produce CO2 when burned, I think that is part of the end process of the fuel cell. But it produces far less then burning oil.
But going back to the OP’s issue of not wanting CO2 production, would it be OK if the CO2 that was released was taken from the atmosphere in the first place. So it is CO2 neutral? In that case we can use biofuels.
Aha. Light bulb moment for me. It should be obvious (anti-AGW 101). I knew greenies are pro-biofuels (except when they’re not, for various reasons). But I never knew the underlying reason, other than “it’s greener!” We’ll ignore the amount of petrochemical fuels used to farm the biofuels for this discussion. Thanks. 
Uhm… it was taken from the atmosphere by the plants which eventually rotted up to become fossil fuels.
But no, you can’t take CO2 from the atmosphere now so that it’s the CO2 you’re releasing from a reaction of fossil fuels and oxygen. The C will come from the fuels; the reason natural gas produces less CO2 than heavier fuels is that the % of C it has is lesser than for heavier fuels - but still, the C has to go somewhere and it’s going to be carbon oxydes.
Then you’ll want to electrolyze water using electricity generated via some means other than burning carbonaceous fuels. That leaves:
-nuclear (fission or fusion)
-hydroelectric
-solar
-tidal
-wind
Depending on how you define “efficiency,” industrial electrolysis of water appears to be 50-80% efficient.
More info here on hydrogen production.
[QUOTE=kanicbird]
But going back to the OP’s issue of not wanting CO2 production, would it be OK if the CO2 that was released was taken from the atmosphere in the first place. So it is CO2 neutral? In that case we can use biofuels.
[/QUOTE]
That is just the opposite of light bulb moment - more like a dim light moment. It will be a great idea IF:
a> Plants (biomass and hence biofuels) could be grown without fertilizers. fertilizers are themselves made from oil or natural gas (Nitrogen fertilizers mostly)
b> Energy rich part of the plants could be harvested, collected, cleaned, dried and Transported without the use of fossil fuels or electricity (that does not happen)
c> The energy rich plant parts at the processing facility could be converted to fuels without using fossil fuels for distillation (driving out the water from the fermentation products)
d>Fresh water was plentiful on earth and taking water out of aquifers for irrigating energy crops was of no environmental consequence
e> Large areas of fertile land were freely available and people did not need to cut down trees to plant energy crops.
If you evaluate the whole cycle of energy and Water usage , you’ll quickly realize that this is not a smart idea and it works only because of political lobbying.
BTW - I have spent more than a decade designing, building, commissioning and operating hydrogen plants and will be posting more later.
See Linde Engineering page on Steam Reforming.
Any conversion of a hydrocarbon to hydrogen will by default produce free carbon (hence, why it is listed in the name ‘hydrocarbon’) and that will naturally bind to atmospheric oxygen to produce carbon dioxide (CO[SUB]2[/SUB]). It is possible to sequester (capture) O[SUB]2[/SUB] produced by such environments by cooling or other methods and from there store it so that it does not enter the atmosphere, but of course that requires more energy. Given what a generally shitty fuel hydrogen is for most applications due to the poor mass energy density, propensity to escape from any sealed system, et cetera, it is unclear why generating pure diatomic hydrogen is so desirable other than the knee-jerk reaction that it is “clean”. With a much smaller natural carbon footprint it is possible to produce dimethyl ether or methanol, both of which are much better fuels for mobile and transportation use, can be used in existing internal combustion engines with as good or (possibly) better efficiency than kerosene and gasoline, and have other nice properties for storage and transportation while offering a vastly reduced carbon dioxide output, and can potentially even be produced using sequestered carbon dioxide.
Stranger
This appears to be true at this time, but is it reasonably possible to expect more with breakthrough’s in things like genetic engineering? Why are we limiting ourselves to the present technology without considering the possibility of future advances.
Because we can better estimate the effects of continuing to do something we already do versus the effects of technologies not yet developed or dreamed of. Magical pie-in-the-sky thinking doesn’t really make for good social or environmental policy. Research should of course continue, but we have to make do with the best data we have at any current moment.
With genetic engineering specifically, what are you proposing?
We already know what happens when we develop GMO plants that perform better. They dominate the landscape and crush native plants and animals. Their toxins hurt unintended targets. Their producers sue nearby crop growers because the GMO pollen happened to fertilize their plants. They are grown in monocrops and deplete soil fertility. They increase pest resistance over time, creating an evolutionary arm race like superbugs and antibiotics.
Don’t see how GMOs can help with this unless you develop plants that locomote themselves to factories. Even so, biological locomotion tends to be less fuel-efficient than wheels and ships, and is subject to metabolic losses that are often greater than electrical efficiency losses in machine transportation. Nature is good at a lot of things, but for getting things from predetermined points A to B, technology is usually more energy-efficient in terms of miles per energy. It all comes from the sun, really, but animals weren’t designed to be optimum, single-purpose transporters.
It’s imaginable that some organism can take care of this process, but again, we have to grow, care for, and transport those organisms. It becomes a cascade of biological requirements, each with their energy needs and environmental dangers. At some point you begin to run into trophic level issues at which each support layer contributes its own inefficiencies to the overall system.
There are only two unharvested sources of fresh water that we know of: Glaciers and processed ocean water. Melting glaciers for their water would have other catastrophic effects. The separation of salt water into fresh water unavoidably requires energy input because the chemical reactions require energy. Using GMOs for this process is possible (some plants and animals do filter salt water into fresh water) but again subject to the same energy, land, pollution considerations as any other designer organism.
This is one of the harder things to get around unless you start using exotic, expensive-to-build-on locations (the oceans, flying things, things on mountains, etc.). Even if your GMO is super efficient and the perfect photosynthetic fuel source, growing it requires space. Terrestrial land is already mostly covered by human agriculture and we can’t spare that much more for first-world energy needs without impacting the rest of the world’s – human and otherwise – ability to survive/thrive.
You can grow stuff in the oceans, but you have to deal with transportation and containment and weather and such. They are not insurmountable challenges, but the math has to be done on a case by case basis and we don’t know how quickly (if at all) we can improve that efficiency curve.
Basically, it’s not that people don’t hope for more efficient technologies, it’s that we can’t COUNT on them until they’re actually reality.
There is the future possibility of utilizing GMO chemosynthesis or radiotrophy (plants/animals that eat hot mineral soup or radioactivity), but that’s quite a ways off, whereas the inefficiencies of photosynthetic biofuels are very apparent today. Presently photosynthesis is about 3x less efficient than PV solar panels, and that gap will widen for quite a while until and unless GMO photosynthesis catches up someday.
Biofuels are often pushed for political and economic reasons and there is a lot of greenwashing that goes on, which is why pie-in-the-sky thinking is dangerous. It compels consumers (and policymakers!) into supporting solutions that may ultimately be less sustainable.
The best I have heard so far is Algae which is much more efficient then ‘crops’ and can be set up anywhere (no transport issue). Last I’ve heard that lab results show that they are able to do the job, but the problem has been making it work on a commercial scale.
Yeah, it’s a very exciting area of work, but it’s not ready for commercialization yet. When talking about biofuels, the two important metrics are ROI (bang for the buck) and EROEI (energy return on energy invested, the same concept but using energy instead of dollars).
The last time we jumped the gun on biofuels (corn ethanol), we came to realize that its EROEI is pretty bad, almost close to 1. Algae’s currently from <1 to about 4. Compare that with oil (10), coal (80), or even other semi-renewables (PV 7, wind 18, hydro 100). This means algae tech has improve by twofold to catch up with photovoltaics, 4x to catch up with wind, and much more to become competitive with fossil fuels and large hydropower. And the financial ROI is worse still, I believe. It’ll be a while yet before algae becomes practical.