5. Technology evaluation
This section builds on the high level technology comparison completed in Section 4 and undertakes a more detailed evaluation of the short-listed reuse technologies. The technologies are evaluated against two key objectives; (1) accelerating cost reductions for CCS and (2) accelerating alternative forms of CCS.
5.1 Methodology and selection criteria
The CO2 reuse technologies are assessed using a set of selection criteria designed to align with the overall objectives for the project, e.g. to determine how and to what extent CO2 reuse can advance the deployment of CCS and to potentially support projects which further the development of promising CO2 reuse technologies. At a high level, this involves understanding the realistic forecast demand for CO2 from different technologies and the commercial potential for captured CO2 to meet this demand.
There are three main scenarios envisaged when implementing CO2 reuse technologies:
- CO2 reuse could provide additional revenues which offset some part of the costs of capture;
- CO2 reuse could also provide long term storage of CO2, and so act as a substitute for geological or other forms of storage (considered an alternative form of CCS); and
- CO2 reuse could provide major additional revenues and so act as a deterrent to long term storage.
With these three scenarios in mind, the following criteria have been selected as the basis for classifying the CO2 reuse technology, to assess the potential impact of the technology in accelerating the deployment of CCS:
- technology maturity.
- potential for scale-up.
- value for money.
- CO2 abatement potential, environmental and social benefits.
These criteria are broken down into sub-criteria, described further in the following sections. A coarse quantitative scoring system was used for the assessment, involving an allocation of one, two or three points against each criterion. For two of the criteria a ‘bonus point’ approach was adopted wherein either a score of zero or one point was awarded.
A score of three indicates positive and reliable evidence that the technology displays preferred characteristic(s) for that criterion. Scores of two or one are corresponding less favourable, with one typically suggesting the technology shows little alignment with the preferred characteristics. The scoring system (three, two, and one) can be thought of in qualitative terms as representing strong, moderate and weak performance respectively for each of the preferred characteristics.
5.1.1 Technology maturity
As identified in Section 4.1, the technologies considered are at different stages of development. Some are at a very early stage, some are approaching commercial operation (demonstration stage), and some are mature, established technologies.
In order for the selected technologies to have an impact in accelerating the uptake of CCS they should be promising technologies ready for commercialisation, as opposed to mature technologies or conceptual technologies some way short of commercialisation.
Whilst it is certainly true that the ‘ready for commercialisation’ technologies are most likely to see rapid growth in the next few years, often this growth is from a relatively small base. On the other hand, there is strong evidence to suggest that some mature technologies already applied on a large scale (for example EOR) still have potential for significant growth in the short term, and as such they warrant consideration as a potential market for captured CO2. Therefore, the criterion does not penalise technologies that are already mature, if there is still growth potential.
This criterion by necessity assumes the technology becomes commercial at some point. The upper threshold of interest has been set to ‘greater than 10 years’ because a realistic carbon price scenario combined with cost reduction in carbon capture technology could result in CCS viability not long after 2020; hence reuse technologies only reaching viability after this point in time are of limited interest, as they do not provide acceleration of CCS. As is outlined in Part 2 – Section 4, the most significant cost reductions in CCS technologies will most likely be realised during the first few gigawatts (GW) of deployment, which is expected to occur in the next ten years.
This criterion has not been broken down into sub-criteria.
Criteria 1.01: Timeframe to deployment
| 3 | <5 years, including newly commercialised and mature technology |
| 2 | 5–10 years |
| 1 | >10 years |
5.1.2 Scale-up potential
This criterion is composed of two sub-criteria: (1) total demand and (2) geographical constraints on the production system.
5.1.2.1 Total demand
This criterion estimates the total realistic level of demand which could be expected to arise from this technology if it reached its maximum potential. To significantly advance CCS, reuse technologies will need to demand large quantities of CO2.
Preference is given to technologies for CO2 reuse which have potential to provide larger volumes of CO2 reuse over time.
This assessment is based on analysis of the possible impacts of CO2 use on the scale and rate of growth of the markets for their products, and the financial position of the manufacturing and other processes.
Criteria 2.01: Total demand
| 3 | >300Mtpa CO2 equivalent (>1 per cent of global fossil fuel emissions) |
| 2 | >30Mtpa CO2 equivalent (>0.1 per cent of global fossil fuel emissions) |
| 1 | <30Mtpa CO2 equivalent (<0.1 per cent of global fossil fuel emissions) |
5.1.2.2 Geographical constraints on the production system
This criterion is designed to complement criterion 2.01, by taking into consideration geographical constraints that may prevent the technology from reaching its full scale potential, or limit its application to a few advantageous locations across the globe.
Criteria 2.02: Geographical constraints on the production system
| 3 | Technology applicable at most locations, products transportable at low cost |
| 2 | The maximum scale of the technology is restricted by land or other resource constraints or only applicable at selected locations or transport of products is relatively expensive. |
| 1 | Major limitations on maximum scale, suitable locations, and ease of transportation of products. |
5.1.3 Value for money
This criterion is composed of three sub-criteria, commercial viability, competitiveness with other technologies and barriers/drivers/incentives.
5.1.3.1 Commercial viability
This criterion considers the costs and the potential revenues of using CO2 in the technology. If there are alternatives to CO2 in the technology, the relative costs of using CO2 and the alternatives are considered.
Criteria 3.01: Commercial viability
| 3 | Predicted to be commercially viable with current market conditions, and without a carbon price or equivalent incentive |
| 2 | Requires either increased market prices for competitor products, or a carbon price, or both, in order to be commercially viable |
| 1 | Never likely to be viable |
5.1.3.2 Competitiveness with other technologies
In order for a CO2 reuse technology to advance CCS, the use of the CO2 would have to be price-competitive with alternative technology achieving the same outcome. For example, for significant uptake of CO2-ECBM to occur it would need to have favourable economics compared to N2-ECBM or flue gas ECBM. As another example, CO2 derived liquid fuels may see reduced demand and price in the future as electric vehicle technology matures.
Criteria 3.02: Competitiveness with other technologies
| 3 | Few or no significant competitor technologies have been identified |
| 2 | Non CO2 based alternative technology pathways/solutions exist that will compete for market share |
| 1 | Significantly cheaper alternative technology pathways/solutions exist |
5.1.3.3 Barriers / incentives / drivers
This criterion considers any financial incentives, such as funding from public bodies, which might support the technology, as well as any other barriers or drivers.
Criteria 3.03: Barriers / incentives / drivers
| 3 | National incentives or legislation exist that will support the technology; no major barriers. |
| 2 | Limited specific support in the form of national incentives or legislation; no major barriers identified. |
| 1 | Major barriers identified. |
5.1.4 CO2 abatement potential, environmental and social benefits
This criterion is composed of four sub criteria; permanence of storage, additional CO2 emissions from reuse, environmental benefit and social benefit, two of which are “bonus” criteria. These are all described in more detail below.
5.1.4.1 Permanence of storage
CO2 reuse that has an alternative form of storage has significant potential to accelerate the uptake of CCS, albeit in an alternative embodiment. For this reason and also because any form of storage is preferred from an environmental viewpoint, CO2 reuse with associated higher degrees of storage are preferable.
Criteria 4.01: Permanence of storage
| 3 | Permanent |
| 2 | Mixture of permanent and non permanent |
| 1 | Non-permanent |
5.1.4.2 Additional CO2 emissions from reuse
Based on the scoping level life cycle assessment (LCA) conducted by Edge Environment (Appendix M), this criterion is intended to quantify the CO2 emissions associated with reuse of the CO2, particularly CO2 emissions due to the energy input into the reuse process. In combination with 4.01 (which penalises when the CO2 is not sequestered), this gives an indication of the lifecycle CO2 performance. It should be noted that this criteria does not take into consideration emissions associated with use of the end product, for example the emissions associated with the utilisation of crude oil extracted by EOR, owing to the wide and varied possible uses of some end products.
From an environmental perspective, reuse technologies that result in significant additional CO2 emissions through the act of reuse are considered less desirable, particularly those that release more CO2 in the act of reuse than if the CO2 had simply been emitted in the first place.
Criteria 4.02: Additional CO2 emissions from reuse
| 3 | Emissions of CO2 per tonne of CO2 reused < 0.5t/t |
| 2 | Emissions of CO2 per tonne of CO2 reused > 0.5t/ t but <1t/t |
| 1 | Emissions of CO2 per tonne of CO2 reused > 1t/t |
5.1.4.3 Environmental benefit (4.03) and social benefit (4.04)
These two criteria are in the form of bonus points.
Technologies that display recognisable environmental or social benefits may derive some advantage from these benefits in the form of a greater likelihood of receiving public and government support.
It is important to note that these criteria only consider those environmental and social benefits which are not directly related to the CO2 abatement potential of a particular reuse technology.
Criteria 4.03: Environmental benefit (non CO2 abatement related)
| Bonus point − 1 or 0 | Example of bonus point: Bauxite Residue Carbonation neutralises a strongly alkaline waste, and the resulting product has the potential to be used as a soil amendment on acidic soils – this has been trialled in Western Australia. This would receive the bonus point. |
Criteria 4.04: Social benefit (non CO2 abatement related)
| Bonus point − 1 or 0 | Example of bonus point: If a particular application has the potential to improve public acceptance, or has higher employment intensity compared to fossil fuel alternatives, it would receive the bonus point. |
5.2 Limitations of analysis
5.2.1 Shortage of information
The investigation to date has taken the form of a desktop based research study, with limited or no contact with industry proponents. Subsequently, a significant hurdle in the analysis was the lack of availability of good quality, reliable information. This was more evident on some technologies than others – those technologies which were less developed or being developed on a smaller scale had less relevant information in the public domain.
5.2.2 Comparability of information
Due to a number of factors such as lack of information, stage of technology development and speciality of technology, it was difficult to perform a like for like comparison of the technologies at a detailed level.
Therefore, based on the above factors, the technologies were assessed on an individual basis and scored separately and distinctly rather than relatively. In cases where there was insufficient information available the score was marked down to reflect this uncertainty.
5.3 Evaluation of short-listed technologies
The following section provides a completed evaluation summary table for each of the short-listed CO2 reuse technologies. The evaluation summary presents the supporting information which formed the basis for scoring as per the criteria outlined in Section 5.1.
Full results of the evaluation scoring process for each technology are provided in Appendix K. The scores are summarised in Table 5.11 with analysis and discussion of the results provided in Section 6.
5.3.1 CO2 for use in enhanced oil recovery
Table 5.1 EOR evaluation summary
| EOR evaluation summary | |
|---|---|
| Timeframe to commercial deployment | Commercialised technology. |
| Scale-up potential | EOR is currently widely employed in the US, but there is significant potential for global growth. |
| Geographical constraints on the production system | Maximum deployment of the technology is constrained by location of depleted oil and gas fields, and transport of CO2. |
| Commercial viability | Technology is commercially viable. |
| Competitiveness with other technologies | EOR technology can be implemented using CO2, water or nitrogen as the transmission fluid. CO2 reuse EOR will have to prove competitive with these alternatives. |
| Barriers / incentives / drivers | Barriers are unclear regulations and uncertain public support (particularly for onshore injection).Driver for deployment is expected demand growth for crude oil . |
| Permanence of storage | During CO2-EOR applications, more than 50 per cent and up to 67 per cent of injected CO2 will return to the surface with the extracted oil, requiring separation and reinjection into the reservoir. At the end of CO2-EOR operations, CO2 should remain permanently sequestered in the depleted oil reservoir. Appropriate measurement, monitoring and verification systems must be in place to verify the permanence of the sequestration.It remains to be seen how the emissions associated with the combustion of the additional oil recovered will be viewed under any emissions trading scheme. Where natural CO2 reserves would otherwise be used for EOR, use of anthropogenic CO2 represents a real net decrease in emissions of CO2. |
| CO2 emissions in the process of reuse | Edge Environment Case Study Result: 0.51t CO2-e/t reused.Case Study Description: Capture from a coal-fired power station near the Dakota Gasification Plant in the USA, delivered via pipeline to the Weyburn CO2-EOR flood (e.g. surface processing and reinjection power comes from the Canadian Grid). |
| Environmental benefits (non CO2 abatement related) | No specific environmental benefits have been identified. |
| Social benefits (non CO2 abatement related) | EOR-based demonstration projects coupled with MMV provide a platform for community acceptance of geological storage as well as valuable storage science and technology learning. |
5.3.2 CO2 as feedstock for urea yield boosting
Table 5.2 Urea yield boosting evaluation summary
| Urea yield boosting evaluation summary | |
|---|---|
| Timeframe to commercial deployment | Urea has been produced on an industrial scale for over 40 years. The technology is well understood and can be considered mature.CO2 capture from reformer flue gas at urea plants is relatively new, first introduced in the late 1990’s. MHI have several units operational in the 100-400tpd CO2 range. |
| Scale-up potential | Urea production is carried out on a very large industrial scale. The size of plant is constrained only by the size of the upstream ammonia facility. A typical plant may produce 1,500 tonnes of urea per day, systems up to 5,000 tonnes per day are considered feasible.However, surplus ammonia from natural-gas based plants may be in the range 5 per cent–10 per cent. Consequently, capture plants installed for this purpose will continue to be <1000tpd in size. |
| Geographical constraints on the production system | Ammonia and urea plants are typically located on the same site and close to major sources of natural gas.Reformer flue gas is the usual choice for CO2 capture, so there is no major geographical constraint on urea yield boosting in that sense. However, CO2 may be captured more cheaply from alternative sources, and delivered via pipeline to the urea plant – this approach is clearly reliant on suitable CO2 sources in proximity to the urea plant. |
| Commercial viability | The production of urea is an established technology with a proven commercial viability, albeit with use of captive CO2. If urea demand (and price) is strong relative to ammonia, then there will be incentive to convert the small per centage of surplus ammonia to urea buying available concentrated CO2 or by installing additional CO2 capture plant. |
| Competitiveness with other technologies | Nitrogen fertiliser is a product with an established global market with current urea prices at US$225-US$290 per tonne. To enter the market the urea produced using recycled CO2 needs to be at or below the current market prices, after processing and transport costs. |
| Barriers / incentives / drivers | The volatility in the price and demand of urea and ammonia makes long term appraisal of the capital investment in CO2 capture plant difficult. |
| Permanence of storage | Not permanent – CO2 is stored temporarily before the reaction used to form urea is reversed when the fertiliser is applied to the land. |
| CO2 emissions in the process of reuse | Edge Environment Case Study Result: 2.27t CO2-e/t reused.Case Study Description: Capture from a coal-fired power station in China, supplying a Urea Synthesis plant via a 9km pipeline. |
| Environmental benefits (non CO2 abatement related) | No additional environmental benefits have been identified. |
| Social benefits (non CO2 abatement related) | No additional social benefits have been identified. |
5.3.3 CO2 as a working fluid for enhanced geothermal systems
Table 5.3 Enhanced geothermal systems evaluation summary
| Enhanced geothermal systems evaluation summary | |
|---|---|
| Timeframe to commercial deployment | >10 years |
| Scale-up potential | A very large theoretical market potential exists, greater than 30Mtpa CO2, based on conservative estimate of approximately 70 EGS sites of 500MWe capacity. |
| Geographical constraints on the production system | Similar constraints as can be expected for CCS; a major point source emitter is required in the region of the geothermal formation. Increased distances will have significant cost implications for compression and pipeline. |
| Commercial viability | Enhanced geothermal systems are unlikely to be commercially viable without a carbon price, and significant investment in the short to medium term. |
| Competitiveness with other technologies | CO2 as a working fluid will have to prove competitive against using water as a working fluid. Similarly geothermal power will need to prove competitive with current energy sources. Displacement of alternatives is unlikely in the short to medium term. |
| Barriers / incentives / drivers | Renewable energy market is expected to see dramatic growth in the next 10 years, with many countries creating incentives for new technologies through renewable energy targets and credit systems.Suitability of geothermal reservoirs as permanent CO2 storage reservoirs is uncertain. |
| Permanence of storage | The process has the potential to sequester permanently, but this is dependent on a suitable capping formation above the geothermal resource. |
| CO2 emissions in the process of reuse | Edge Environment Case Study Result: 0.58t CO2-e/t reused.Case Study Description: Capture from coal-fired power stations in SE QLD, Australia, delivered via a 970km pipeline to the Cooper Basin, Australia. |
| Environmental benefits (non CO2 abatement related) | No specific additional environmental benefits identified. |
| Social benefits (non CO2 abatement related) | No specific additional environmental benefits identified. |
5.3.4 CO2 as feedstock for polymer processing
Table 5.4 Polymer processing evaluation summary
| Polymer processing evaluation summary | |
|---|---|
| Timeframe to commercial deployment | 5–10 years |
| Scale-up potential | Assuming a conservative 4 per cent annual growth on existing PE / PP markets over the next five years, and assuming a displacement of 40 per cent of the PE and PP market would see over 30Mtpa CO2 used as feedstock.The price fluctuations of finite petroleum feedstock could also lead to increased use of CO2 feedstock polycarbonates and scale-up potential. |
| Geographical constraints on the production system | Technology is applicable at most varied locations. |
| Commercial viability | Commercial viability of the technology will depend on the products being accepted by the existing market. Some uncertainty due to lack of reliable information and demonstration projects. |
| Competitiveness with other technologies | Novomer claims products can be used as an alternative to existing petroleum based polymers, though this is still to be verified. |
| Barriers / incentives / drivers | Difficulties of entering existing product market.However, volatility of petroleum prices may drive deployment of technology. |
| Permanence of storage | Depends on end use – in pure form CO2 polymers can degrade and break-down (re-releasing CO2), in as short as 6 months in the right conditions. On the other hand the produced polymer may be embedded in a long-life product. |
| CO2 emissions in the process of reuse | Edge Environment Case Study Result: 5.5t CO2-e/t reused.Case Study Description: Capture from a coal-fired power station in the USA, delivered via a 9km pipeline to the polypropylene carbonate production facility. |
| Environmental benefits (non CO2 abatement related) | No additional environmental benefits identified. |
| Social benefits (non CO2 abatement related) | Carbon capture in items such as plastic bags and food packaging, which are used regularly, could make the issue of carbon abatement more relevant and practical to help public acceptance. |
5.3.5 CO2 for use in algae cultivation
Table 5.5 Algae cultivation evaluation summary
| Algae cultivation evaluation summary | |
|---|---|
| Timeframe to commercial deployment | 5–10 years |
| Scale-up potential | Commercial scale systems would be in the region of 10–100Ha. And may be expected to absorb anywhere between 500 and 55,000tpa CO per system. |
| Geographical constraints on the production system | The amount of CO which can be captured from a point source will be constrained by the land available on a case by case basis. Systems are ideally suited to locations with high solar irradiance and adequate marginal land. Access to a water source is also important. Products can be readily transported using existing methods and infrastructure. |
| Commercial viability | The likely use of the algae would be for the large scale production of bio-fuel which has a large potential market. It is forecast that by 2022 algae bio-fuels will be the largest bio-fuel category overall, accounting for 40 billion of the estimated 109 billion gallons of bio-fuels produced (Bradford 2009).The high land requirement may limit the commercial viability of the technology in areas with high land prices. |
| Competitiveness with other technologies | On a wider scale algae bio-fuel will have to compete with current fuel sources (e.g. petroleum) if it is to be considered as a commercial alternative for use as a transport fuel. At present it appears unlikely that algae bio-fuel will be able to compete with alternative products in the current market. |
| Barriers / incentives / drivers | The technology is most suited to regions with high solar resource and large areas of marginal land surrounding point CO2 sources (providing the most productive environment for algae cultivation) which will inhibit the implementation of the technology in many regions.The use of algal bio-fuels avoids the current food vs. fuel problems surrounding first generation soy/palm/corn/wheat/canola bio-fuels. |
| Permanence of storage | CO2 which is absorbed by algae is used to generate biomass. Dependent on the system there may be a mixture of end products produced from this. A basic system may generate only biodiesel in this case the storage is temporary as the CO is re-released when the fuel is burnt. Another system may generate biodiesel, supply crude algal oil for processing to plastics, useful nutraceuticals may be extracted and used in food supplements, the algal biomass remaining after extraction may then go on to produce animal feed, fertiliser, biochar or to be digested anaerobically to produce biogas. Some of these avenues will result in semi-permanent storage, and those that displace fossil fuels also have an indirect mitigation effect. |
| CO2 emissions in the process of reuse | Edge Environment Case Study Result: 0.41t CO2-e/t reusedCase Study Description: Algae farm integrated with a coal-fired power station in Eastern Australia, with process requirements similar to those identified in public documents of MBD Energy |
| Environmental benefits (non CO2 abatement related) | Algae cultivation systems can be used as a step in waste water treatment – to remove certain compounds from waste water/sewage. When char is produced from the algal biomass, it may be used as a soil conditioner. Algal meal when used as a livestock feed may reduce methane emissions. |
| Social benefits (non CO2 abatement related) | Algae systems which are constructed on marginal land and used to produce bio-fuels would not compete with food crops for arable land. The use of algal bio-fuels avoids the current food vs. fuel problems surrounding first generation soy/palm/corn/wheat/canola bio-fuels. |
5.3.6 CO2 as feedstock for carbonate mineralisation
Table 5.6 Carbonate mineralisation evaluation summary
| Carbonate mineralisation evaluation summary | |
|---|---|
| Timeframe to commercial deployment | <5 years |
| Scale-up potential | Market potential greater than 300Mtpa CO2 equivalent, considering global aggregate consumption in excess of 30 billion tonnes per annum. |
| Geographical constraints on the production system | The maximum scale of the technology is restricted by the available resources of brine and flyash to provide the requisite hardness and alkalinity required. If the brine source is not suitable or an abundant in supply then the technology requires manufactured alkalinity. |
| Commercial viability | Likely to be commercially viable without the need for a carbon price or similar incentive. |
| Competitiveness with other technologies | Initial market entry may be hampered by potential public perception of the products being inferior to existing alternatives and for the method to be accepted and approved by regulators. |
| Barriers / incentives / drivers | Plant capital cost still relatively high. |
| Permanence of storage | Permanent |
| CO2 emissions in the process of reuse | Edge Environment Case Study Result: 0.32t CO2-e/t reusedCase Study Description: PB Estimate of requirements based on capture at a brown-coal fired power plant in Victoria, Australia, with no requirement for manufactured alkalinity.Actual result could be significantly higher, depending on the source of alkalinity, transportation distance, and end use. |
| Environmental benefits (non CO2 abatement related) | The technology has the capability to reuse flyash in the process which in the future may be considered and designated as a hazardous material requiring regulated storage. |
| Social benefits (non CO2 abatement related) | One of the by products is fresh water that could be used as potable water, irrigation water, or an industrial water supply, which may alleviate the water deficit in some regions. |
5.3.7 CO2 for use in concrete curing
Table 5.7 Concrete curing evaluation summary
| Concrete curing evaluation summary | |
|---|---|
| Timeframe to commercial deployment | Based on plans for a demonstration plant in 2011, commercialisation could be achieved as early as 2012. |
| Scale-up potential | Based on 5 billion tonnes of concrete used globally per annum, and an estimated 10 per cent is pre-cast concrete, there is potential for 60Mtpa of CO2 to be sequestered by concrete curing. |
| Geographical constraints on the production system | The reuse of CO2 for concrete curing can only occur at precast concrete plants. Generally onsite flue gas emissions will be used, and/or from local/ neighbouring combustion sources. |
| Commercial viability | The technology has potential for commercial viability, assuming it becomes proven. Concrete curing, via a moist, controlled environment, is an established practice required to strengthen and harden precast concrete. |
| Competitiveness with other technologies | Concrete cured using this technology is unlikely to be able to be sold at a premium over existing products and therefore its competitiveness will be determined by the costs that can be saved (through reduced curing times, carbon tax etc.) in using this technology over traditional methods. |
| Barriers / incentives / drivers | The main barriers to concrete curing is the limitation of its use to existing concrete producers due to the requirement for it to be implemented at the precast concrete plants. The main drivers and incentives for the commercialisation of the technology are the potential to reduce curing times of concrete and the ability to capitalise on any applicable carbon schemes. |
| Permanence of storage | The mineral carbonation and curing process presents permanent storage of CO2 for centuries in the form of precast concrete products. |
| CO2 emissions in the process of reuse | Edge Environment Case Study Result: 2.20t CO2-e/t reusedCase Study Description: Utilises a flue gas slipstream from a coal-fired power station in Nova Scotia, Canada, with the precast facility located in close proximity. |
| Environmental benefits (non CO2 abatement related) | There are no hazardous chemicals needed or produced by this process, the only by-products are water and heat. |
| Social benefits (non CO2 abatement related) | No specific social benefits have been identified. |
5.3.8 CO2 for use in bauxite residue carbonation
Table 5.8 Bauxite residue carbonation evaluation summary
| Bauxite residue carbonation evaluation summary | |
|---|---|
| Timeframe to commercial deployment | <5 years. |
| Scale-up potential | Limited. Technology only utilises approximately 30kg CO2 per tonne of dry residue. |
| Geographical constraints on the production system | Requires local, high concentration source of CO2 in proximity to aluminium refinery. |
| Commercial viability | Has been proven to be commercially viable at current scale by Alcoa (2.5Mpta residue treated using 70,000tpa CO2), however this particular project is only viable because of the presence of a stream of concentrated CO2 from a local ammonia plant. |
| Competitiveness with other technologies | Resulting product has limited use, and is not expected to have a commercial value. |
| Barriers / incentives / drivers | A high concentration (and potentially high pressure) of CO2 is required.To be commercially viable, a local source of CO2 is required. |
| Permanence of storage | CO2 which is converted to carbonates is permanently sequestered. Further utilisation of CO2 is possible by conversion to bi-carbonates, however over the long term, the CO2 would be released from bi-carbonates in the conversion back to carbonates. |
| CO2 emissions in the process of reuse | Edge Environment Case Study Result: 0.53t CO2-e/t reused.Case Study Description: Capture from a coal-fired power station in Western Australia, supplying the Kwinana Alumina Refinery via a 9km pipeline. |
| Environmental benefits (non CO2 abatement related) | Reduces dusting potential of red mud (currently an environmental hazard) and reduces the area of land and cost required for red mud disposal. |
| Social benefits (non CO2 abatement related) | No specific social benefits identified. |
5.3.9 CO2 as a feedstock for liquid fuel production
Table 5.9 Liquid fuel production evaluation summary
| Liquid fuel production evaluation summary (renewable methanol; formic acid as a hydrogen energy carrier) | ||
|---|---|---|
| Timeframe to commercial deployment |
|
|
| Scale-up potential | Displacement of 10 per cent of the world’s fossil petroleum consumption with renewable CO2 derived fuels would represent in excess of 1Gtpa CO2 recycling. | |
| Geographical constraints on the production system |
|
|
| Commercial viability |
|
|
| Competitiveness with other technologies |
|
|
| Barriers / incentives / drivers |
|
|
| Permanence of storage | Non-permanent.For mobile transportation, it is reasonable to assume that CO2 released from the combustion of the liquid fuels derived from CO2 cannot practically be captured for further processing or reuse. | |
| CO2 emissions in the process of reuse | The CO2 balance depends largely on the source of electricity. A dedicated renewable source of electricity has small emissions intensity, and consequently the additional emissions of CO2 would be less than 0.5t CO2 per tonne CO2 reused.However, if grid power is used, the majority of countries have sufficiently high emissions intensity that the CO2 balance is not so attractive.Renewable Methanol Case Study Result: 1.71t CO2-e/t reused; Case Study Description: Capture from the Svartsengi Geothermal Power Plant (Iceland), process heat and power also supplied captively from this power station.Formic Acid Case Study Result: 3.96t CO2-e/t reused; Case Study Description: Capture from a coal-fired power station in Korea, supplying CO2 to the electrolysis plant via a 9km pipeline | |
| Environmental benefits (non CO2 abatement related) | No additional specific environmental benefits have been identified. | |
| Social benefits (non CO2 abatement related) | No specific social benefits have been identified. | |
5.3.10 CO2 in enhanced coal bed methane recovery
Table 5.10 Enhanced coal bed methane evaluation summary
| Enhanced coal bed methane evaluation summary | |
|---|---|
| Timeframe to commercial deployment | Timeframe to commercial deployment is considered a minimum of 5 years away given the technical constraints to be overcome. |
| Scale-up potential | Coal seams are the most abundant fossil fuel deposits (in comparison to oil and gas reservoirs) so there is nominally potential for ECBM to become widespread on un-mineable coal seams if the technology barriers can be overcome. Results from research in 29 possible ECBM sites in China have been used to estimate that nominal CO2 storage potential is about 143Gt in the country’s known coal beds. |
| Geographical constraints on the production system | Maximum deployment of the technology is constrained by location of coal beds, and transport of CO2 and natural gas. |
| Commercial viability | Technology may be commercially viable if further research succeeds in overcoming technical barriers, and as market conditions (natural gas price, carbon price) change. |
| Competitiveness with other technologies | The ECBM process may alternatively use N2. The Alberta study has shown that flue gas (which comprises mainly of nitrogen and carbon dioxide) injection has its merits. Therefore, when economic and CO2 storage factors are considered, there might be an ideal CO2/N2 composition where both factors will be optimised. |
| Barriers / incentives / drivers | The primary barriers are the technical and related cost constraints on injectivity, and the potential sterilisation of coal resources that could be mined in the future using deep conventional mining methods or underground coal gasification.The driver for deployment is expected demand growth for energy in natural gas, potentially incentives provided by western governments offering a carbon price. |
| Permanence of storage | Storage of CO2 once injected in a coal seam is essentially permanent, as it is adsorbed to the coal. A key assumption is that coal seam remains undisturbed, and is not subsequently mined or gasified in-situ in the future. |
| CO2 emissions in the process of reuse | Edge Environment Case Study Result: 0.44t CO2-e/t reusedCase Study Description: Capture from a coal-fired power station in China (Yancheng), supplying a commercial ECBM operation in the South Quinshui Basin via a 50km pipeline. |
| Environmental benefits (non CO2 abatement related) | No specific environmental benefits have been identified. |
| Social benefits (non CO2 abatement related) | No specific social benefits have been identified. |
5.4 Summary of evaluation scores
The completed evaluation for each of the short-listed technologies can be found in Appendix K. The scores are summarised in Table 5.11 below.
Table 5.11 Evaluation scores
| Various | Mineralisation | Liquid fuels | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Criterion | EOR | ECBM | Urea | EGS | Polymers | Algae | Carbonate aggregate | Concrete curing | Red mud carbonation | Renewable methanol | Formic acid |
| 1.01 Timeframe to deployment | 3 | 2 | 3 | 1 | 2 | 2 | 3 | 3 | 3 | 2 | 1 |
| 2.01 Scale-up potential | 3 | 3 | 1 | 2 | 2 | 2 | 3 | 2 | 1 | 2 | 3 |
| 2.02 Geographical constraints on the production system | 2 | 2 | 3 | 1 | 3 | 2 | 2 | 1 | 2 | 2 | 2 |
| 3.01 Commercial viability | 3 | 2 | 2 | 2 | 2 | 2 | 3 | 2 | 2 | 2 | 1 |
| 3.02 Competitiveness with other emerging technologies | 3 | 3 | 2 | 1 | 2 | 1 | 2 | 2 | 2 | 2 | 1 |
| 3.03 Barriers/ incentives/ drivers | 2 | 2 | 2 | 1 | 2 | 1 | 2 | 2 | 1 | 2 | 2 |
| 4.01 Permanence of Storage | 2 | 3 | 1 | 2 | 1 | 3 | 3 | 1 | 2 | 1 | 1 |
| 4.02 Additional CO2 emissions from reuse | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 0 | 0 |
| 4.03 Environmental benefit (Non CO2 abatement related) | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 0 | 0 |
| 4.04 Social benefit | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 0 |
| 1. Technology maturity | 100% | 67% | 100% | 33% | 67% | 67% | 100% | 100% | 100% | 67% | 67% |
| 2. Scale-up potential | 83% | 83% | 67% | 50% | 83% | 67% | 83% | 50% | 50% | 67% | 83% |
| 3. Commercial viability | 89% | 78% | 67% | 44% | 67% | 44% | 78% | 67% | 56% | 67% | 44% |
| 4. CO2 abatement potential, environmental and social | 50% | 63% | 38% | 63% | 63% | 75% | 88% | 75% | 75% | 38% | 38% |
| Total (no weighting) | 77% | 77% | 58% | 50% | 65% | 65% | 88% | 62% | 62% | 54% | 46% |
