Cycle it back into plants
Could you take this "pure" co2 and put it into sealed greenhouses to grow plants? They would have to be large, agreed, but the best method of carbon sequestration is surely photosynthesis ?
Boffins in the States say they've come up with a way of making fuel cells run on coal gas - the fuel of Victorian streetlights - and steam. Their plans would, they say, offer much lower carbon emissions than normal coal power: and much easier sequestration of exhaust gases as their technology would emit nearly pure CO2. "This …
just release it to the atmosphere.
It's not that CO2 doesn't get converted to carbohydrates in plants it's the RATE of CO2 production that's the problem with the current use of fossil fuels. Not enough growing area to absorb it all. Putting it into a greenhouse only helps a little if at all and you need to make the glass.
Plants take CO2, water and sunlight to make sugar. Some of the fastest growing plants store 1.5% of energy they get from sunlight in sugar. The only good thing about plants is that they are much cheaper than the cheapest solar panels (which are about 15% efficient).
In real life, intensive farming requires chemical fertilisers. These fertilisers require a large amount of energy to produce. The energy used for creating and transporting fertiliser is greater than the energy stored by converting plants into biofuel. On top of that, energy is required to transport water to the crop and to transport the crop to the processing plant.
Trying to get energy from plants is a huge waste of valueable farmland. All the CO2 captured is released again when the biofuel is burned (or the food is eaten). On top of that, you need the energy from the coal power station to make the fertiliser and run the distribution chain.
This admirable technological advance will only give an end-to-end improvement if we have a safe (physically, environmentally, radiologically, even) way of mining the coal in the first place, and of converting it into coal-gas in the second place. Those of us old enough remember that gas-works were dirty, smelly establishments, though I don't doubt that modern technology could do better.
The fact remains that coal straight out of the Welsh steam coal seam is not pure carbon, much less so brown coal. Any attempt to turn it into pure fuel gas is going to have to separate and sequester those impurities, including but not limited to the sulphur and nitrogen compounds.
hurr mining produces carbon
by your own standards the mining, transportation and refining of the silicon, aluminium, copper, tin, silver, lead, titanium, cadmium, tellurium, indium, gallium, selenium, arsenic - all solar panels require a subset of these, generally at least 4 of them.
then construction and transportation of the panels
then installation, the fact that people are looking at small scale, per house installations...
or we could do a tear down of wind power, i'll leave that as an exercise for the reader.
building a nuke plant or a solar panel manufacturing facility all require materials, and then they need fuel to produce energy or products.
everyone wants to include the nuclear plant in the cost footprint of nuclear energy, which is fair. few seem to want to include all the factories required to make solar cells, possibly because there are so many and usage/production would define the footprint heavily. its still something you need to account for though.
if someone produced a complete teardown of resources required and waste produced for all the competing power technologies to allow a resource/waste per watt produced breakdown, well it'd be an impressive spectacle indeed. without it you can just throw up useless arguments all over the place, can't you.
There is CO2 released during mining, transportation and refining of Uranium. Only because of the use of fossil fuels to power the processes involved. If the mining, transport and refining equipment was powered by nuclear power, the whole process would become self-sustaining releasing no more CO2 for those acts.
But I bet you would immediately jump onto the CO2 released during the manufacture of the equipment used to mine, transport and reprocess still waving your CO2 banner.
Taken as a pure energy generation solution, Nuclear is the greenest source out there.
There is but you could use electric tools (many mining rigs are electric so they dont have to get exhaust fumes out). Most importantly Coal, Oil or Gas plants needs many many tones of fuel all the time that they are running; Nuclear plants can have one patch of fuel last a very long time.
The biggest energy cost of a nuke is the concrete to make all the walls; but if you powered the concrete factory on Nuclear power that goes down quite a bit (I think making concrete outputs CO2 direclty on top of the huge amount of heat & power it needs).
Nuke - Better than fossil fules even if it is not perfect; even kills less minors...but only coz there are less of them needed. Not a perfect world but maybe a better one.
"There are various cunning schemes to manufacture synthetic "natural" gas or even petrol from CO2, using surplus renewable or nuclear power."
WTF? So you can turn coal into electricity at about 50% efficiency releasing CO2, and then using electricity that you have too much of, you can convert that CO2 into fuel in another non-optimal processes, ending up with a fuel you can burn. (Which is what you started with, but you've just lost most of the energy in the process)
Surely, if you have an excess of electricity, it would be better to use that directly for what you want electricity for, and reduce the coal to a burnable gas if a burnable gas is what you want.
Where is the half-baked idea icon?
But then, if you look a litle deeper. There are several high-demand/long running mobile applications where our current battery technology cannot suport the draw for what has become expected in terms of time/distance. Cars, Lawnmowers, leafblowers... for these applications gasoline(petrol)/Natural (unnatural?) gas, are our current best option. Hydrocarbons carry a *lot* of energy in a very small package.
To have a weedeater with the power and longeviy of a regular 2-stroke jobby would requre a battery bigger than most adults* .
One could make a similar arguement to creating heat to make electricity to generate heat (space heaters), or trapping light to create electricity to create light. It's all about converting energy to the form you need. Sometimes it seems backwards, and sometimes it is; but I do not believe that that is the case in this case.
*may be an exaduration, especially on the US side of the pond
Excess electricity is a relative term. It's only "excess" if there is no demand for it. You could use electrical plant off peak capacity to produce Hydrogen from water if you wanted to but it's not very efficient. Petroleum is still the best way at present to store and distribute portable energy in relative safety.
"So you can turn coal into electricity at about 50% efficiency releasing CO2,"
Yes, but remember that 50% is comparable to 33% efficiency for current processes. So you're already getting 1.5x the energy out of the coal to start with.
Now let's assume that all of the _extra_ electricity is used to convert the waste CO2 into fuel.
That would mean that , at the end of this proposed process, you will have obtained:
A. the same amount of energy you would have obtained with the current processes, and
B. fuel to burn for more energy.
This, as opposed to the current processes, which gives you A and waste.
Which would you prefer?
This is not to mention the following quote from the article:
--If hybridised with coal-gas burning turbines this could climb to 80 per cent.--
which would mean that you'd get about 2.4x the energy out of the same amount of coal than the current processes gives.
"Yes, but remember that 50% is comparable to 33% efficiency for current processes. So you're already getting 1.5x the energy out of the coal to start with."
Unfortunately, it appears that the article has confused the efficiencies of coal-fired and nuclear power stations.
Modern, "current", coal-fired plant can achieve 45+% conversion, chemical to electrical, with the limiting factor being the Carnot efficiency of the steam cycle.
Nuclear (current designs) is unable to create steam of the same quality so the Carnot efficiency is around 33% (look familiar).
Though to make a real "apples to apples" comparison, you should look at the potential of the fuel that is actually converted. For an LWR, the utilisation of fuel potential is 5% (6% if the MOX cycle is included) so you end up with an efficiency, fuel potential to electricity, of 1.667% efficient.
Of course, these figures only apply to the energy conversion process and exclude energy use in associated activities, eg mining/extraction, transport, processing/re-processing, sequestration, etc, that all affect the full life-cycle efficiency...
But, of course, that kind of analysis doesn't lead to tight, snappy headlines.
The thing is; the process for turning CO2 and H2O into jet fuel is designed for when you are in the middle of the sea, with lots of electricity from nuclear powered turbines, lots of water and can extract CO2 from the air (or somewhere).
If you are on land with COAL, there are other processes to turn COAL into a usable gaseous or liquid fuel without distilling coal, oxidising in a fuel cell to produce electricity and then using that electricity to convert some of the CO2 into a gaseous or liquid fuel. There are processes to convert coal to diesel and ethane or petrol. Some of these processes have been around since the 20's
Either use the coal to make electricity at a higher efficiency than you do now (although the Chinese are getting very efficient due to the limits on coal and amount of power they want), sequester the CO2, or emit it (but less than old turbine tech). Or use the coal to make another fuel that is more flexible, but do it directly.
coal powered Nissan leaf? I mean it feels like it is in the way it doesnt accelerate and you have to stop ever 100m or so to refuel it. Get a kid off the street to keep shoveling in fresh coal and you'd be away. Not sure what the cost per mile would be but at least you could get the range up.
Better still I'm planning on buying an electic bike and outfitting it with dynamos to recharge the battery while I'm riding it.
Free energy forever!!
It seems a few commenters don't get the difference between using carbon in the carbon cycle and releasing it from carbon sinks such as coal....
Comments are going downhill.
You can have one, too - no need to bother with an intermediate electricity step, either. Just get a classic ammonia based RV fridge, the type intended to run on propane OR electricity. Swap out the jets to get the air/fuel mix right, and you can use good old coal gas just as well as propane. They aren't as efficient as electric compressor jobs, but they skip the inefficiencies of the electric conversion, transformer and transport steps, which gives you a pretty good end result - better than if you're trying to produce your power via a small, inefficient ICE or diesel generator.
A coal slurry was the original fuel Kelly Johnson had earmarked for what became the SR71.
Were it *possible * to carve big rings of coal out of a coal seam they could be inserted into the casing of a hybrid rocket, with LO2 providing the oxidiser. *Potentially* very cheap and fairly good performance but from a safety point of view a design you can shut *down* in an emergency.
Sadly they don't mine coal that way.
According to the Register's (paid for) editorial policy:
- CO2 DOES NOT CAUSE GLOBAL WARMING!!!
- GLOBAL WARMING IS A PINKO COMMIE CONSPIRACY PERPETUATED BY CORRUPT SCIENTISTS, NASA, NOAA, BIG OIL, THE PENTAGON AND AL GORE TO ENRICH THEMSELVES WITH **MY** TAX DOLLARS.
- GLOBAL WARMING MELTS ARCTIC ICE (WHICH IS *NOT* MELTING)
WHICH IS GOING TO COOL THE OCEANS (WHICH ARE *NOT* WARMING) THEREBY SAVING US FROM GLOBAL WARMING (WHICH **DOES NOT** EXIST)
- YOU CAN'T PROVE ANYTHING ANYWAY.
So why the F**K are we supposed to suddenly care about CO2 emissions?
Hopefully this silly idea is a dying gasp of the American coal industry. We can only hope.
The main problem with coal versus other non-renewable hydrocarbon sources is that it is so dirty. Natural gas is far cleaner. All of the gunk that is mixed in with the hyrdocarbons has to be handled. Originally, it was ignored, so is spewed into the atmosphere. Nowadays there are expensive cleaning rigs on the smoke stacks to capture some of it. It's always there, however - you have to do something with it, and hopefully that something isn't "deposit it into the lungs of air breathing creatures and onto plants". Oh yes, the "doing something with it" is hard, expensive, and uses up a lot of the energy you were trying to produce in the first place.
...and throwing away most of the energy in transmission losses? The same gas could be distributed through pipes and used for heating with an efficiency of something like 90%. Politicians like gas power stations: they are clean, have low capital costs and release less CO2 than coal plants. Good PR, but extraordinarily wasteful. A classic example of how short-termism triumphs over strategic thinking.
If you have various power sources providing power not when you want (nuclear - always on, solar, wind, wave at any time) then you use the fuel cells to meet peak power demands and any offpeak surplus gets plowed (inefficently I agree) into a useful fuel.
Love the idea - fingers crossed about practicality, long term reliability, manufacturing cost etc.
The process of cooking coal to produce gas is an old one. And here the developers seem to have bypassed well established facts: coal is not easy to handle and is full of nasties. The coal gas process includes a massive clean up to remove sulphur, hydrocarbons and tars each element with disposal problems. We used to be able to deal with these problems but that was before we became H&S concious.
Anyone who has experience can well remember that you knew where the Gas Works was because you could smell it from about half a mile away (and that is no exaggeration). The loss of this was one of the advantages to North Sea gas.
Given that you need nearly 100% base load on fossil/nuke to cope with demand for when the wind doesn't blow or the sun doesn't shine (OK I know daylight will do, but there's still nighttime) then anything produced by these means could be regarded as surplus (and expensive surplus at that).
Now if we'd invested in geothermal or tidal, that could be different
"In an operational plant, about half the CO2 would be recirculated back for use in gasifying the coal. The rest, once the water was removed, would be emitted as a pure stream of CO2: much easier to capture and use or sequester than the stack gases coming out of a normal coal power station."
Bah. Keep the water and CO2 mixed, bottle it, and sell it as tonic. Profit!
Producing the coal gas will require lots of heat input ( from somewhere ) and is a filthy process, I Do Recall, however useful the by-products. The gas then needs to be combined with steam made with high grade heat ( from somewhere ) and introduced to nickel and yttria-stabilized zirconia ( wow! ) electrodes - provided by a fluffy bunny - to produce The Nice Safe Rectifiable Direct Current power. And water and CO2. Lots of CO2. Did I hear somewhere that CO2 can be cracked at ~400 degrees ( C, from somewhere ) in the presence of another fluffy bunny-provided catalyst ? Liberating O2 and leaving pure carbon powder. Which I suppose you could then burn again for high grade heat to make coal gas, flash up steam, crack its own leftover CO2 and warm the fluffy bunny's evening bath filled from the fuel cell. CO2 surplus to requirements can be used to grow tomatoes**.
Can't quite decide where to start with all that...
I say - transit to a mixture including Thorium nuclear for 'leccy, IMBY by all means & Somethin Really Daft like, say, electrically compressed air stored in nice dumb re-usable tanks. For at least some transport and as portable energy. Naive ? Motors and wheels will still turn. Transport industry jobs can adapt. Re-fuelling frequency might slow us all down a bit, an acknowledged Good Thing. Yeah, Double-plus naive.
*Is the Title of this mentardation & No relation
** All commentards recommending CO2 enhanced greenhouse horticulture are or have been hemp-growing hippies and I claim my ₤5.
NOTE: If any of the above does happen to work, I claim a cut ( to be advised ), promising to devote 31428571%pts of any future massive wealth to protecting endangered species by nicely ensuring people leave them-the-fuck be.
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