Carbon Capture and Storage Flashcards
1
Q
What is CCS?
A
- Power plant
- CO2 can be captured from a process or the atmosphere and permanently stored geologically
2
Q
What is required for CCS?
A
- Transport to transfer it to the site
- A suitable injecting site
3
Q
Why do we need CCS?
A
- Oil and gas will reach a plateau
- Coal consumption projected to drop by 60% in 2050
4
Q
What will remain a major source of energy globally?
A
Fossil fuels
5
Q
What sectors are the major contributors to emissions?
A
- Electricity and heat
- Aviation and shipping
6
Q
How much CO2 does the IEA say has to be sequestered?
A
120 Gt CO2 by 2050
7
Q
How much CCs do we have?
A
About 50 MtCO2/a operational
8
Q
How much CCS do we have in various stages of development?
A
About 310 MtCO2/a
9
Q
What is conventional combustion?
A
- You have a mix of hydrocarbon and air and when combusted will result in flue gas
10
Q
What does the combustion of hydrocarbon and air generate?
A
Hydrogen and CO2
11
Q
What is post combustion capture?
A
Uses a solvent to capture CO2 from the flue gas of power plants
12
Q
Describe steps of post combustion capture?
A
- Separate your flue gas
- Will have a pure CO2 stream and clean flue gas
- Then separate CO2 and nitrogen
13
Q
What is pre combustion capture?
A
- Avoids have CO2 gas in the flue gas in the first place
- aka clean combustion
14
Q
What does pre combustion capture convert the fuel into?
A
Hydrogen with steam and oxygen
15
Q
What is oxy-fuel combustion?
A
Where the separation is done before the combustion
- Separate air into nitrogen and oxygen and combust fuel with pure oxygen
16
Q
What stage is the concept stage?
A
TRL1
17
Q
Which technology readiness levels prose the most challenges?
A
TRL3, TRL6 and TRL7
18
Q
What category is TRL9?
A
Commercial
19
Q
When was post-combustion first patented?
A
1930
20
Q
How do the solvent and CO2 interact in post-combustion?
A
- Solvent absorbs CO2 to regenerate solvent and this is heated up so CO2 boils out
21
Q
Why type of energy is used for the solvent regeneration in post-combustion?
A
Parasitic energy
22
Q
What is beneficial about the post-combustion technology?
A
- Retrofittable
- CCS can be installed after
23
Q
What pressures is post-combustion done at?
A
1- 2 bar_a
24
Q
Where has there been commercial deployment of post-combustion plants?
A
- Boundary Dam, Canada
25
How much did the boundary dam in Canada cost?
£840 M
26
At what temperatures do amines degrade?
120˚C -140˚C
27
When is solvent susceptible to chemical degradation?
Susceptible to chemical degradation in O2, SO2, CO2, high temperatures
28
Why are degradation products bad?
Degradation products could present health risks, need to be monitored → cancer
29
What was the measured amine loss from the first pilot plant?
≈ 0.35 - 2.0 kg solvent/tCO2
30
What are the disadvantages post-combustion?
- High CapEx - large gas volumes → large equipment
- Parasitic energy ➔ reduced plant efficiency
- Solvent losses & solvent disposal
31
What is the process of post-combustion capture?
1. Adhesion of species/molecules to a solid surface
2. Porous solids are used in a cyclic process to
separate gas mixtures
32
What research focus is typically associated with sorbent regeneration for CO2 capture?
Vacuum Swing Adsorption (VSA) due to fast cycle times and greater throughput
33
Why has Temperature Swing Adsorption (TSA) not been traditionally considered for sorbent regeneration?
Due to longer cycle times of more than 6-12 hours
34
How does TSA compare to VSA in terms of CO2 recovery?
TSA offers better CO2 recovery compared to VSA
35
What does the degree of absorption of COP2 depend on?
Pressure concentration and temperature
36
What are the key features of rotary absorbers in commercial applications?
- Laminated gas channels with adsorbent coated on laminations
- negligible pressure drop
- higher gas throughput
37
How does the rotary absorber function to increase efficiency?
By putting material on a rotary wheel and rotating the wheel about one revolution per minute
38
What is the purpose of exposing the other half of the rotary wheel to steam?
To heat the solvent for enhanced performance
39
What are the advantages of post combustion capture?
- Retrofittable
- Range of operating conditions, many potential materials available
- Particularly well suited for low concentrations ➔ direct air capture
- Potentially cheaper and more environmentally friendly than amine absorption
40
What are the disadvantages of post combustion capture?
- Challenging material selection
- Need for cyclic processes
- Energy requirements to generate vacuum
- So far only used for small volumes, expensive to scale up
41
How does the process of pre-combustion CO2 capture work?
- Take a fuel like coal, gas or biomass
- React with steam and oxygen
- CO2 is separated from
The first part of the process is identical to the conventional H2 production process
42
What happens when steam and oxygen react in pre-combustion capture?
- Syngas proudced
43
What happens when syngas is reacted?
CO2 and H2 produced
44
What are the CO2 capture options in pre-combustion?
- Pressure swing adsorption
- Cryogenic separation
- Physical absorption
- Chemical absorption
45
When was pre-combustion first employed?
1966
46
What is the basis of cryogenic separation in pre-combustion capture?
It's fundamentally based on the different boiling and condensation points of species
47
What are the boiling points of CO2, CO, and H2 at 7 bar_a?
CO2: -50 °C, CO: -170 °C, H2: -244 °C
48
Why is cryogenic separation not economically feasible if CO2 content in syngas is less than 40%mol?
Because it requires a significant amount of energy to cool the gas stream down
49
What are the advantages of pre-combustion?
- Uses processes that are already commercially used
- Lower energy penalty than post-combustion capture
- Overall hydrogen production process can be very efficient (60 – 65%) – does not include efficiency of power plant!
50
What are the disadvantages of pre-combustion?
- High CapEx - high cost
- Complex process – low flexibility
- No commercial scale demonstration of pre-combustion capture for power generation
51
What takes place in oxyfuel combustion?
- O2 separated from air
- Fuel is combusted in pure oxygen
- Flue gas (ideally) only contains H2O and CO2
- H2O can be condensed
- No further separation of CO2 is required
52
What is the most sensible method for air separation to produce O2 and why?
Cryogenic distillation, due to its maturity, very high capacity and purity, though it has high energy requirements
53
Why is vacuum swing adsorption not suitable for high capacities in air separation?
While mature and capable of producing high purity O2, its capacity is medium, and it cannot achieve very high capacities
54
What are the characteristics of membrane technology for air separation?
High purity, very low capacity
55
Why is cryogenic air separation considered expensive?
Due to its high energy requirements
56
Where do cement emissions come from?
2/3 form limestone
57
How can gas turbine CCS technology be applied to cement production?
It can be applied to the flue gas from the furnace to capture CO2
58
How is CO2 transported?
Pipelines and ships
59
What are examples of small scale CCS?
trucks, rail
60
Under what conditions is CO2 transported?
100 bar, 30˚C or liquified
61
What is CO2 storage reattach based on?
- Site characterization
– Plume migration
– Managing risks of leaking
– Detecting leaks with certainty
62
How much of properly stored CO2 will remain over 10,000 years?
>98%
63
Why might CCS processes emit more CO2 than they capture?
Due to the emissions associated with the additional energy required to operate the CCS technology
64
What is the difference between Captured CO2 and Avoided CO2?
Captured CO2 refers to the gross amount of CO2 captured, whereas Avoided CO2 refers to the net CO2 after accounting for the emissions from CCS operations
65
What factors impact the cost of CCS?
- Location in the world
- Technology
- Labour
- Commercial
- Capture process
- Transport
- Storage
66
What does the learning curve show?
Costs will reduce over time as more plants are built
67
Whats the most expensive thing to do in the whole CCS process?
Most expensive thing to do is build the first commercial plant
68
How does cost change with concentration of CO2?
It becomes more expensive to separate a more dilute stream
69
How much CO2 present in air?
0.0004%mol
70
What does net negative mean?
Net negative is removing more CO_2 from the atmosphere than you emit
71
What is Biochar in the context of GGR technologies?
Biochar involves harvesting a tree, converting it into charcoal to trap CO2, and then burying the charcoal in soil or the ground
72
How does Direct Air Capture (DAC) work for removing CO2?
DAC technology captures CO2 directly from the atmosphere by using a chemical agent, like amine, to absorb CO2, which is then removed and stored permanently
73
What is Ocean Fertilization as a GGR method?
Ocean fertilization aims to increase algae growth in the ocean, which in turn captures and stores CO2 in biomass
74
What is BECCS?
A feasible technology that combines bioenergy production from biomass with carbon capture and storage to reduce atmospheric CO2
75
What are important considerations for BECCS deployment?
Social aspects and acceptance, ensuring the technology is welcomed and supported by communities
76
What is the purpose of life cycle analysis in BECCS?
To calculate net carbon removals by accounting for all emissions associated with the process, ensuring a genuine reduction in atmospheric CO2
77
Is BECCS 100% efficient in capturing and storing CO2?
No, it is not 100% efficient, indicating that some emissions may still be released or not all CO2 generated is captured
78
How can CO2 capture be utilised?
- EOR
- Chemicals
- Plastics
- Food/beverage
79
What are the disadvantages and advantages of DACCS?
- Lower land requirement
- Higher social acceptance
- Energy consumer
- Very expensive
80
What are the disadvantages and advantages of BECCS?
- Higher land requirement
- Lower social expectance
- Energy producer
- Cheaper
81
What does performance of plants depend on?
Where you are in the world
82
What is DACCS?
DAC reduces the carbon dioxide concentration in the atmosphere as a whole through absorption
83
What are the global CO2 emissions per year?
35000 MT/yr
84
Why are we not seeing any CCS? From a political standpoint.
- Regulations and permitting
- No mandates for CCS
- Carbon prices not high enough
85
Why are we not seeing any CCS from an economical standpoint.
- No inherent value: not doing CCS will always be cheaper
- Product (CO2) has no value
- Transport & storage infrastructure
86
How can we make CCS a commercial reality?
- Reduces capital costs for developer
- Incentives for carbon capture
- Mandates
- Pick the right application
87
What are the criticisms of CCS?
- Unreliable / technically infeasible
- Increases emissions
- Prolongs use of fossil fuels
88
What is greenwashing?
Greenwashing is when a company falsely claims its products or practices are more eco-friendly than they actually are, misleading consumers.
89
What is CO2 a waste product of?
Industrial sewage
90
What should CO2 removal possibly be based on?
historical emissions
91
What can CCS provide?
- CCS can provide value with power system resilience
- CCS can provide emission reductions for industry
