Challenges surrounding CCS

As mentioned in a previous post earlier this week, the IEA’s CCS roadmap had a number of targets and plans laid out, with priorities on actions required before 2020. They mention that a number of these are not where they had hoped by 2014, and there has been a delay in pushing CCS projects and programmes forward.

There are big challenges associated with CCS projects. Their size and scale leads to complexity, as does the requirement to integrate numerous stakeholders, technologies and systems, along a number of value chains. On top of all of this, there is a lack of understanding as to why CCS is important, and discussions around whether there is even a need to reduce or remove CO2 emissions does not help.

So what, at a very high level, are some of the key challenges that are being encountered?

The scale of CCS required:

It’s estimated that, in order to reduce global emissions by 10% (keeping in mind that the IEA targets 14% by 2050), the volume of CO2 needed to be captured and stored annually is roughly the same as the volume of oil produced.  This is not an insignificant target, and it is likely that the majority of centralised power systems will need some form of carbon capture technology installed to achieve this.  This means retrofitting or incorporating into new builds, and there are naturally impacts on energy generation efficiency.  There is also a lot of work required to move technologies forward, and to prove the effectiveness and efficiencies of the capture, transportation and storage technologies.

R_DProgress

[Source: IEA Technology Perspectives 2015 presentation.]

Integration of many individual technologies and processes in a single system

The targets are big, the infrastructure required is vast and the CCS system encompasses the capture, transportation and ultimate storage of CO2; three unique, distinct and technically complex sectors, all with their own regulatory hurdles and policy related challenges.

There are also a number of stakeholders who are involved or need to be consulted to get CCS projects off the ground. The public and private sectors need to work together, as public and private infrastructure interfaces are impacted, and government policy leads to changes in private sector spend and operations.

Costs

The cost of separating carbon is largely dependent on the industrial or power generation process involved. This capture and compression process can be responsible for around 70-90% of the overall CCS expense. Costs relating to transportation are impacted by the need for new infrastructure and storage costs can vary greatly, depending on the nature of storage being pursued.

There is a lot of emphasis within the CCS sector on the importance of R&D and on large scale demonstration projects in order to a) improve the predictability of costs associated with CCS and b) bring those predictable costs down.

The financial case for CCS is also largely driven by carbon pricing, and the inclusion of CO2 emissions in power prices or in the input costs for industrial processes.

CCS Cost_pricing

[Source: IEA Insight Series 2014, CCS Legal and Regulatory Review]

Awareness and public interest

A lack of concern by the public on the seriousness of climate change will naturally lead to a lack of understanding as to the value of CCS, and the urgency related to the permanent removal of CO2 from the industrial and power sector processes. Motivating for the allocation of funding to research and development and to demonstration projects will be harder where there is not public support, particularly given the high R&D and capital costs associated with CCS technologies.

Capturing carbon – the basics

In order to store the carbon, you first need to capture it.  There appear to be three main ways to separate the CO2.  This post is not intended to be a thorough technical discussion; I am neither qualified nor inclined to go into the detail, however, it’s interesting to have a basic understanding of what happens where.

Generating gases with CO2 concentration:

CO2 is typically captured in one of three stages of fuel combustion: flue-gas separation, oxy-fuel combustion or during pre-combustion.

  1. During flue-gas separation, or post-combustion capture, the gases resulting from burning fuels includes various gases, including N, CO2, H20, SO2 etc.  The assumption is that the fuel combusts by reacting with air.  This means that there’s a high concentration of nitrogen component in the flue gas.  In order to separate the CO2, the Nitrogen will need to be removed => energy required.
  2. In oxy-fuel combustion, the fuel is burnt with oxygen (or as near to pure O2 as possible).  This removes the nitrogen prior to combustion, meaning that the concentration of CO2 is much higher in the exhaust gases, making it easier to separate.  Naturally, there would have to have been effort involved prior to combustion to separate the oxygen from the air => energy required.
  3. Pre-combustion capture “involves reacting a fuel with oxygen or air and/or steam to give mainly a ‘synthesis gas (syngas)’ or ‘fuel gas’ composed of carbon monoxide and hydrogen. The carbon monoxide is reacted with steam in a catalytic reactor, called a shift converter, to give CO2 and more hydrogen.” [source: IEA Clean Coal]  What results is a mixture of gases with a much higher concentration of CO2 than in post-combustion processes.  This can be cheaper to operate than options 1 and 2, however the capital costs can be higher.
CO2 capture[Source: hindawi]

Separating the CO2:

Once there is a gas with a high enough CO2 concentration, there are a few ways to separate the CO2.  This short document, produced by the CO2 Capture project, outlines three methods of removing CO2 from mixed gases; namely separation with

  • sorbents/solvents;
  • membranes; and/or
  • cryogenics.

CO2 Capture project

 

What happens to CCS captured carbon

Geological storage:

Carbon Capture and Storage or Sequestration typically conjures images of the injection of carbon into a suitable underground cavity, with appropriate geological characteristics.  The CO2 captured is then permanently trapped within these cavities.  As shown in the diagram below, there are a number of types of cavities or geological structures that can be used.

IPCC Geological storage

Source: IPCC Special report on SRCCS

Options 2 and 4 above make use of CO2 as an input in an industrial process; namely to assist with the recovery of oil, gas or coal bed methane.  CO2 is injected and the pressure assists in forcing more fuel upwards.  Effectively this is storing CO2 to assist with accessing more fossil fuels which will result in more CO2.  However, the use of CO2 helps to decrease the net emissions in the overall process, based on the assumption that the oil would have been accessed in the first place.  If pressurised CO2 is injected into the cavity after the completed depletion of the reservoir, it could also be considered to be a net sink.

Option 3 involves the injection of CO2 into a saline, or brine, solution.  This is water that is rich in minerals, and unsuitable for agricultural purposes.  This may not be suitable for areas aiming to access geothermal potential of underground water deposits.

Mineral carbonation:

This involves the formation of stable carbonate materials through controlled chemical reactions with calcium or magnesium compounds.  The output of this process can be used in construction or building projects, and the carbon is permanently trapped.  There are naturally challenges associated with this process, not least of which is the mining required for the minerals to be used as inputs to the process.  The capture of carbon and the chemical process itself requires energy.  The IPCC considers that such a facility would require 60-180% more energy than a power facility without carbon capture or mineral carbonation processes.

IPCC_Mineral carbonation

SOURCE: IPCC SPECIAL REPORT ON SRCCS

Industrial applications:

CO2 is used as an input in a number of industrial processes.  The potential for diverting CO2 captured and using this in such processes is being explored.  One of the key considerations relates to the resulting industrial output, and whether the CO2 remains permanently stored therein.

Excluding CO2 as an input in enhanced oil recovery (discussed above), CO2 is also used as a reagent in fertiliser manufacture, methanol production or is used for other applications, such as a refrigerant, in fire extinguishers, in soft drink carbonisation, in plastics production or in algae cultivation.  As the IPCC indicates in their special report on CCS (link above), “as a measure for mitigating climate change, this option is meaningful only if the quantity and duration of CO2 stored are significant, and if there is a real net reduction of CO2 emissions. The typical lifetime of most of the CO2 currently used by industrial processes has storage times of only days to months. The stored carbon is then degraded to CO2 and again emitted to the atmosphere. Such short time scales do not contribute meaningfully to climate change mitigation.” 

Given that nearly half of all carbon capture and storage is expected to be within the industrial sector (including EOR), it is important that the effectiveness of the solutions are considered and monitored.  Particularly as the IPCC states that, “in view of the low fraction of CO2 retained, the small volumes used and the possibility that substitution may lead to increases in CO2 emissions, it can be concluded that the contribution of industrial uses of captured CO2 to climate change mitigation is expected to be small.”

 

IEA_CO2_captured uses

 

[Source:  IEA Energy Technology Perspectives 2015 presentation]

Where this becomes important is in the cost of the overall CCS system.  Where CO2 is considered to be an input into an industrial process, the cost of separating carbon at a power station can be offset against its value in the process.  Storage for the sake of storage (e.g. underground storage without EOR applications) cannot be offset, unless other energy generation options are suitably priced for carbon.

Carbon Capture & Storage and its role in climate change mitigation

The International Energy Agency (IEA) hosted a webinar on the 11th September, focusing on the findings of their Energy Technology Perspectives report for 2015.  One of the topics covered was around Carbon Capture and Storage (CCS).  This topic had come up in the IGB Conference held in Singapore recently, and it seems to be more topical as Paris’ COP21 approaches.

CCS is the separation of CO2 from power generation or industrial processes.   This CO2 is then transported and permanently stored, possibly underground, or as part of a new chemical or substance.  The aim is to remove the CO2 from the atmosphere, or avoid allowing the CO2 to reach the atmosphere in the first place.

IEA_CCS

 

[Source – IEA Energy Technology Perspectives 2015 presentation]

 

In their scenario where global warming is kept beneath a 2 degree increase threshold, the IEA’s model has CCS contributing 1/6 of CO2 emission reductions in 2050, and totalling 14% of cumulative reductions between 2015 and 2050.  Its role is therefore not insignificant.  The IEA has found that the inclusion of CCS is economically justifiable, given that the 2deg scenario would be approximately 40% more expensive to achieve if CCS is not included.

Most of the savings are expected to come from the power sector, but they also note that 45% of savings will come from industry.  Furthermore, it is expected that most of the focus will need to be in non-OECD countries.  70% of the total mass captured is expected to come from non-OECD countries, with China accounting for 1/3 of all CO2 captured between 2015 and 2050.

Total CO2 savings required for 2 degree scenario by region:

IEA_Total_CO2_Savings_Country[SOURCE – IEA ENERGY TECHNOLOGY PERSPECTIVES 2015 PRESENTATION]

But with such a key role to play in mitigating climate change, the progress on projects, amounts spent, incorporation of CCS into industrial sectors has not been as advanced as expected by the IEA in their 2013 Roadmap.

In this they laid out seven actions in order to achieve the widespread application of CCS technologies.  These are below.  The IEA indicate that these are critical, particularly as many of their targets are aimed at 2020.

  • “Introduce financial support mechanisms for demonstration and early deployment of CCS to drive private financing of projects.
  • Implement policies that encourage storage exploration, characterisation and development for CCS projects.
  • Develop national laws and regulations as well as provisions for multilateral finance that effectively require new-build, base-load, fossil-fuel power generation capacity to be CCS-ready.
  • Prove capture systems at pilot scale in industrial applications where CO2 capture has not yet been demonstrated.
  • Significantly increase efforts to improve understanding among the public and stakeholders of CCS technology and the importance of its deployment.
  • Reduce the cost of electricity from power plants equipped with capture through continued technology development and use of highest possible efficiency power generation cycles.
  • Encourage efficient development of CO2 transport infrastructure by anticipating locations of future demand centres and future volumes of CO2.”

Over the next week, Energy Ramblings will be looking into some of the technologies that exist, some of the projects that have been built, the progress made against targets, and some of the challenges that are being experienced along the way.