The value of screening studies in the development of carbon capture projects

The development of a carbon capture project is a major undertaking that will require significant time and resources. Time spent in planning during the early stages is seldom wasted and will help to ensure that the finished project will perform in line with the owner’s/operator’s requirements and expectations.

There are many different capture approaches available, and each have their advantages and disadvantages. Even though carbon capture has been available at project scale since the 1980s, relatively few projects have been completed. The current realisation that there is an urgent need to decarbonise to minimise the impact of man-made global warming has led to a significant increase in interest in carbon capture.

A carbon capture project, whether as an element of a new build facility or as a retrofit to an existing one, requires almost the same development approach since many of the steps in the development process are common to both scenarios.

One of the first decisions is what capture approach to use. This is an important consideration as it will impact the costs both to build the project and to operate it over many years. Captimise recommends that a proper evaluation of available, suitable, capture technologies be performed, considering the requirements of the technologies against the ability of the plant to provide these. This is done through a screening study, an evaluation of the expected needs and performance of capture technologies for a specific emitter plant, which helps determine the optimal capture solution for the plant, expressed in economic terms. It is normally the case that mature technologies, those with a Technology Readiness Level (‘TRL’) of between 7 and 9, are recommended to minimise risk given the costs of a project. Technologies of levels 7 to 9 have all been shown to work in an operational environment.

Screening study

A screening study is best undertaken at the early (pre-feasibility) stages of a project. It will support and augment the owner’s and operator’s understanding of how carbon capture will impact the plant. It is an iterative process, with the plant owner supplying information, the adviser looking at various capture options (in line with the owner’s risk appetites) and a regular dialogue between the two parties as the study moves towards its next phase to provide a solution that best accommodates and aligns with the owner’s objectives. It typically takes ten weeks to complete.

Roadmap

The first stage is to define the roadmap and the basis of design. There are four key components to this (see below):

1.Decide the in-service date. This will determine how much time is available to develop and build the plant. The more time available, the more flexibility will be available in the development options.

2.Once the in-service date has been established, the steps that have to take place to achieve this need to be mapped out and appropriate time for each step allocated.

3.The next stage is to consider how much risk the owner is prepared to take in the capture technologies being evaluated for use. It is common for three or four technologies to be chosen for evaluation although more, or less, can be considered at the owner’s option.

4.The final part of this first stage is to look at integration issues − how will the carbon capture

plant be added to the plant? A new build plant incorporating carbon capture is relatively straightforward, but for a retrofit at an existing plant, key considerations are availability of both space and connections to heating, cooling and electrical power.

Once those preliminary considerations have been established, the screening study itself can start. The first consideration is, for each of the potential capture options to be evaluated, the energy requirements to run the carbon capture plant. Electricity, steam and cooling requirements are considered and the availability of these elements from the emitter plant, or from external sources, is identified.

Costs

The next stage is to look at costs. Capital costs for the hardware required by each technology under consideration will vary based on what is required for the capture plant itself, and what may be required by the operating elements of the carbon capture plant compared to what is already available; there are instances where it was necessary to build a stand alone heat plant to provide the heat requirements of a carbon capture retrofit.

A decision around whether to go for a turnkey construction contract or another approach will need to be made. Another consideration may be the possibility of moving to a new capture technology at some point during a project’s life; new capture technologies are being developed all the time, and some are offering significantly reduced operating costs. Consideration may therefore need to be given to the use of a capture plant using currently available, proven technology for less than the planned operating life of the project with a view to replacing this with a technology that is currently in development, but which will offer significant operating cost savings when it matures and reaches the higher TRL levels. Capital costs are written off over a time period and profile agreed with the plant’s tax authorities, often in equal fixed amounts in each operating year.

Simultaneously with the capital costs, for each capture solvent under evaluation, operating costs need to be determined - for the solvents required, the electricity, heating and cooling needed for capture and (if required) liquefaction. Heating costs of the capture process may include foregone revenue from a heat offtaker, where heat used in the capture process reduces heat available for other possibilities. Inflation will impact, usually increase, the operating costs each year and thereby comprise the largest cost element over the life of a project.

The combination of the two sets of costs will allow the total costs of the capture project to be calculated and these provide the basis for comparison, in capture performance adjusted cost terms, between the capture alternatives.

When the desk work has been completed, the analysis can be proven through the use of a capture demonstration unit. This is a small, stand alone, capture unit capable of capturing typically between one and five tonnes of CO2 per day, although units capable of capturing larger volumes are available to order. In addition to providing information on capture rates, CO2 purity and degradation of capture solvents, it allows fine tuning of solvents and catalysts to optimise the capture rate and provides an understanding of the carbon capture process for plant personnel and an early opportunity for plant operators to work with carbon capture. There are usually significant public relations benefits.

Ultimately, it helps to prove the analysis ahead of the final investment decision being taken.