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Topic Title: The Carbon Capture and Storage Pipe Dream
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Created On: 27 September 2013 05:30 PM
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 27 September 2013 05:30 PM
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jarathoon

Posts: 1043
Joined: 05 September 2004

The BBC is running a story [press release?] today that Carbon Capture and Storage would work more efficiently if we burnt our fuel in pure oxygen using a different theromodynamic cycle.

"Could [fossil fuel] power plants of the future produce zero emissions?" By Pia Gadkari BBC News, Washington

http://www.bbc.co.uk/news/business-24225901

"Rodney Allam, chief technologist at 8 Rivers Capital, which owns Net Power, says: "The perception has been that to avoid emissions of [carbon dioxide] CO2, we have to get rid of fossil fuels.

"But unfortunately, fossil fuels represent over 70% of the fuel that's consumed in the world and the idea that you can get rid of that in any meaningful sense is a pipe dream." "

At the moment CCS is an even bigger pipe dream I'm afraid than dramatically slashing our fossil fuel use via the use of renewables (together with a system of cross border power grid interconnects).

In fact all our options for a future without CO2 emissions at the moment are pipe dreams of one sort or another.

The duty of the engineer is to find the pipe dreams that can be cost-effectively converted to reality, within a reasonable timescale.

I don't think CCS, in the forms so far proposed, will be one of them at the moment as they are fighting against the first and second laws of thermodynamics.

The fact we don't have enough secure places to hide away the CO2 underground is also a major problem.

The only long term hope for the CCS process (if CO2 can be captured efficiently) is to utilize solar energy in the north African deserts to convert concentrated CO2 back into energy somehow (or to allow for long term storage in the form of Calcium Carbonate say). More pipe dreams.

Anyway Allams CCS solution is to separate Oxygen from air somehow and then burn fossil fuel gas to generate electricity. The outputs water and CO2 can then be separated off.

http://netpower.com/

No thermodynamic efficiencies for the "Allam Cycle" are presented.

He has moved the gas separation process to the input stage of his power station, which means he will have to take considerable amounts of energy from the grid in order to start this power station up. It also means that this system will need to be very reliable or will require large amounts of oxygen to be stored if they want to keep the plant producing energy in the event of a oxygen separation plant breakdowns.

Presumably he thinks cryogenic separation (or other method) of oxygen form ambient air is less difficult and less costly than cryogenic separation (or other method) of CO2 from the warm moist air output from a power station.

If he is producing his oxygen cryogenically he needs to warm it up prior to use in the combustor.

As far as I am aware non-cryogenic methods of oxygen separation are targeted at small scale production of oxygen only. If his company has found a non-cryogenic method of separating oxygen from air that is energy efficient and can be cheaply scaled up then this would be a remarkable achievement indeed.

It maybe more cost effective to split oxygen (and hydrogen) from water.

Another pipe dream.

James Arathoon

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James Arathoon
 28 September 2013 03:20 AM
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jarathoon

Posts: 1043
Joined: 05 September 2004

"An expert view on Carbon Capture and Storage"

From Myles Allen
Professor of Geosystem Science, Oxford University

https://www.youtube.com/watch?v=YGc6knmpL2E

This is public education video brought to you on Shell's YouTube Channel

Myles Allen's advice at the end of the video

"Until Carbon Capture is made compulsory, made a condition of extracting fossil carbon out of the ground we won't be building the technologies we need to avoid dangerous climate change"


According to David Hone (Climate Change Advisor for Shell) this video gives "A clear explanation of why we need carbon capture and storage"

http://blogs.shell.com/climate...e/2013/09/ccsclarity/

Well the clarity is remarkable, especially in regard to the extremely broad sweep of this radical idea. Unfortunately though he gives no timescale for action, so the clarity isn't complete.

Ok lets do what the expert says and add this requirement to the Energy Bill currently going through parliament, and debate the missing timescale. There is so much crazy stuff in this bill it won't hurt if we add some more.

Lets say that after 20XX (to be agreed by debate e.g. 2035):
- All our fossil fuel electricity stations would need carbon capture devices fitted.
- All our cars and lorries would need carbon capture devices fitted.
- All gas boilers in every house in the uk would have to carbon capture devices fitted.
- In fact nobody at all would be able to use fossil fuels after 20XX without capturing all the carbon emitted in its combustion.

Remember according to the expert view, carbon taxes or carbon pricing will not work; only making carbon capture a condition of extracting fossil fuels will work.

Professor Myles Allen's web page
http://www.eci.ox.ac.uk/people/allenmyles.php

Shell and its advisors must be pretty confident that CCS will be cost competitive with renewable energy solutions over the next decade or two. This confidence is really quite remarkable given how poorly the technology has performed in tests so far.

James Arathoon

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James Arathoon
 28 September 2013 11:39 AM
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ReSusTech

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The only long term hope for the CCS process (if CO2 can be captured efficiently) is to utilize solar energy in the north African deserts to convert concentrated CO2 back into energy somehow ...
.

This is technically feasible and is in fact what I refer to as CCR, (Carbon Capture & Recycling). It could also be a solution to providing the massive amounts of energy storage (multi TWh) that are likely to be required if intermittent RE sources (e.g. wind wave & solar) are to provide a substantial proportion of our generating capacity.

Since I first became aware of CCS, I've thought that there was something fundamentally wrong with taking the waste from fossil power stations and dumping it in the ground; when we (the UK) do this with ordinary waste we are charged £70+ per tonne for doing it, even if it is totally neutral waste such as soil or clean rubble. If the same principle was applied to Fossil waste CO2, i.e. recycle it or pay £70 per tonne for dumping it, there might be a bigger incentive to find a more sustainable solution to the problem as it would add about £200 to a tonne of coal!

Returning to the concept of CCR, CO2 can be reacted synthetically with hydrogen to produce carbon, either directly via the Bosch process or indirectly via 2 or more other processes. Recycling CO2 synthetically in this way would be at least an order of magnitude more efficient than normal photosynthesis (excluding algal bioreactors with concentrated CO2 feed) and billions of times quicker than producing coal nature's way. Further more the regenerated fuel products (green coal (elemental carbon) or synthetic hydrocarbons) would be pure fuels free from the range of impurities that occur in fossil fuels and, in the case of biofuel production from biomass, would not require the large amounts of nutrients and huge areas arable land needed to produce biomass.

I refer to this overall concept as a 'Synthetic Closed Carbon Cycle' (S3C) incorporating CCR.

Now consider the fact that there is a proven technology, albeit in early development stages and not at commercial level yet, that can convert carbon directly into electricity at about 80% efficiency actual (100% theoretical) and has pure CO2 as a waste stream. Further consider how easy and cheap it would be to store and transport elemental carbon 'green coal'. Further more, it would also be much easier and cheaper to transport waste CO2 for recycling than transporting hydrogen, and the green coal route would not require a continuous new supply of water for regeneration.

The only thing I don't understand about this concept is way I don't seem to be able to generate any serious interest in developing it, although from information I received a year or so ago the Chinese may very well be doing so. If, or more likely when, they do, I don't think there will be much call for our (UK's/Europe's) conventional CCS approaches, pre or post combustion!

The S3C concept also has many other potential advantages, one of which could be to provide a mechanism for C neutral shipping.

Nick Cook
TMIET
 28 September 2013 07:47 PM
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jarathoon

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Joined: 05 September 2004

In Germany they have built a small scale power to gas plant, able to produce hydrogen and synthetic methane

If you create hydrogen and oxygen from water it requires energy
4H2O + Energy [286 kJ/mol) + losses] -> 4H2 + 2O2

Burning methane in pure oxygen can create pure CO2 and Energy
CH4 + 2O2 -> CO2 + 2H2O + Energy [ - 882.0 kJ/mol]

Converting CO2 back to methane using hydrogen requires energy e.g. Sabatier reaction
CO2 + 4H2 + Energy -> CH4 + 2H2O

http://en.wikipedia.org/wiki/Sabatier_reaction

This can only be a closed cycle if fossil fuel burning in air without carbon capture is outlawed (as suggested by Myles Allen in the Shell video).

In practice this would only be applicable to electricity generation, unless we all have cost effective carbon capture pods in our cars and lorries, which could be emptied and recharged somehow at petrol stations.

Using renewable electricity directly will always be cheaper than using it as part of a closed carbon capture and recycling process. Therefore we don't need this closed cycle for electricity generation, except as a way of storing electrical energy, and there seem to be much more efficient ways of storing electricity currently being investigated.

What we really want to do is to try to keep carbon fuels for long distance transportation whilst slashing the net release of CO2 to the atmosphere, from burning them.

We can get offsetting CO2 in concentrated form from
a) anaerobic digestion (biogas) [separating the CO2 from the methane]
b) combustion of biomass
c) quicklime production
d) some active volcanoes

But I doubt this will be enough, unless we use the North African deserts to grow things or grow seaweed for fuel on netted beds suspended using buoys a few feet under the turbulent ocean wave surface (and thus collect the CO2 from the ocean surface layers not the atmosphere).

Collecting low concentration CO2 from the atmosphere or the ocean without relying on nature would I expect end up as being more expensive.

James Arathoon

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James Arathoon
 29 September 2013 04:57 PM
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jarathoon

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Joined: 05 September 2004

To remind you Professor Myles Allen's advice in the Shell video above is

"Until Carbon Capture is made compulsory, made a condition of extracting fossil carbon out of the ground we won't be building the technologies we need to avoid dangerous climate change"

Lets consider the domestic gas market, for home heating and cooking

The UK's domestic demand for Gas can be seen in this document

As a very rough estimate domestic use is 50 TWh per quarter in Q2 and Q3, and 140 TWh per quarter in Q4 and Q1.

Which is around
- 64GWt needed during the whole of Q4 and Q1
- 11GWt needed during the whole of Q2 and Q3

If we assume a 50% combined cycle gas combusion efficiency to generate electricity plus grid losses we would need
- 128GWt (64GWe) in Q4 and Q1
- 22GWt (22GWe) in Q2 and Q3

That means we need an extra 64 GWe of electricity generation only 11GWe of which is needed all year round.

For the 11GWe with up to 100% utilization
At £2500 per KW this costs £27.5 billion to build
At £4375 per KW [Third gen Nuclear] this costs £48 billion to build

For the 53GWe with only around a 50% utilization
At £2500 per KW this costs £133 billion to build
At £4375 per KW [Third gen Nuclear] this costs £231 billion to build

But the cost of electricity would be much higher than currently estimated for new nuclear because most of the assets are only utilized 50% of the time. Therefore cost of heating would skyrocket, to somewhere between 5 and 7 times current levels.

So the Professor Myles Allen Plan alternative would be to collect the CO2 from households in a new waste gas grid (remember we could only use gas if we did this), operated say on the local authority level. As long as we can store CO2 and methane we can process the waste gases all year round at the same rate.

The question is, will it be more costly to build a new waste gas collection infrastructure, plus the Gen IV nuclear stations or renewable energy sources necessary to convert CO2 to methane all year round, plus money for extra methane and CO2 storage,

than,

building an extra 64 GWe of carbon free electricity generation capacity, 53 GWe of which is only needed for half the year, plus the cost of upgrading the electricity network to cope with these new power flows in winter.

Probably spending money on insulating housing to a much higher standard, will pay off better than either of these two options.

James Arathoon

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James Arathoon
 29 September 2013 05:12 PM
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jarathoon

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Sorry the link to Government Gas trends document is here

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James Arathoon
 01 October 2013 06:14 PM
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jarathoon

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Joined: 05 September 2004

I think it may be better to build triple floor green houses in the desert to capture carbon, than buidling other sorts of artificially engineered devices for capturing carbon.

For each 1 acre of desert land you get say 2.5 acres of cultivation. With light pipes taking light to the lower floors.

High temperature tolerant crops on the top floor, plants which can grow in medium levels of light on mid floor and low levels of light on the ground floor.

A 500 km square area of desert (61.7 million acres) could perhaps grow enough biofuels for over 100,000,000 cars (assuming around 400 litres of ethanol per acre + food crops and nitrogen fixing plants), depending on fuel efficiency and miles travelled per year.

The problem of stopping the level of CO2 climbing in the atmosphere and oceans is transformed into one of cheaply engineering vast acreages of multilevel greenhouses in the desert regions in this particular pipe dream. There is a materials production cost problem to solve and a lot of the materials costs will be from the energy costs of manufacture. These may be a lot simpler problems to solve than finding places to store CO2 under ground, esp[ecially if we can develop generation IV molten salt nuclear reactors, to help make the glass, reinforced concretes and ceramics needed.

Obviously new technologies for sowing and harvesting have to developed. Energy for desalination and fertilizer production is required.

If you grow plants material that can be aerobically digested you have a way of making methane and concentrating CO2 for feeding into the greenhouses.

James Arathoon






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James Arathoon
 01 October 2013 08:27 PM
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jarathoon

Posts: 1043
Joined: 05 September 2004

This north african greenhouse pipe dream is quite interesting.There might even be enough fuel for 300,000,000 fuel efficient hybrid cars out of 500 km2 of north african desert, using triple story greenhouse cultivation.

In America this would mean being able to fuel all of North America's vehciles from a land area equivalent to the size of Wyoming. And you would get food crops out of this same land area as well. The desert areas of Australia could be a good place to build large area triple floor greenhouses as well.

For all the Mathusian stories of doom and gloom about over population[David Attenborough please note] and catastrophic this and catastrophic that, humans still have a very bright future on this planet; we just have to be smarter about how we engineer our farming systems and introduce uprated systems of diplomacy and conflict resolution so we don't engage in so many wars.

We can even keep much the same transport systems we have today if we use the north african deserts and other hot deserts to mankinds collective benefit. We can use the equatorial seas to grow more stuff as well.

We may need to move the people currently employed by the fossil fuel industry and gradually reassign them to high tech agriculture, materials and reducing the costs of renewable and nuclear energy instead.

James Arathoon

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James Arathoon
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