Welcome to the Cquestrate blog
We have recently commissioned two pieces of research to develop the process.
The first part addresses the Energy Balance of the process – how much energy is required to drive the process? While we know how much energy is required to thermally decompose (calcine) limestone into lime and carbon dioxide (this is after all what people in the lime industry do every day), we need to change the process slightly, so that we are able to capture pure carbon dioxide, which is much easier to sequester. Through contacts from this website I have been in touch with the German Lime Association who have been able to provide some very useful and encouraging information on current energy requirements and indications on what the requirements for the altered system might be. At the same time as we are gathering empirical data, we are also creating a computer model of the energy requirements of the altered calcination system – this work is being undertaken by Dr Panos Parris and Dr George Manos both at University College London. They will be reporting out in the first week in September.
The second piece of research is on the environmental impact of adding the lime to seawater. This work is being carried out by Professor Gideon Henderson, Dr Heather Bouman and Dr Ros Rickaby, all at the Department of Earth Sciences at the University of Oxford. This research will be a preliminary assessment of the effects of the process and will identify further areas of research to determine whether, and how, this process can be conducted in an environmentally beneficial way. They will be reporting out in the middle of September.
As part of the open source approach we are taking, we will publish the research results on the website as soon as we receive them
The process requires energy: energy to quarry the limestone, energy to crush it into pieces, energy to calcine it into lime and energy to dispose of the lime in seawater. This section examines how much energy is required. If that energy is supplied by a carbon-containing fuel, then carbon dioxide will be generated – the amount of carbon dioxide generated will depend upon the type of fuel used.
- How much energy is used in the production of lime in current industrial processes? How much heat energy is used (to heat the limestone) and how much electrical energy is used (to drive machinery)?
- How much carbon dioxide is generated during the production of lime (both from the calcining of the limestone and from the combustion of the fuel)? How does this amount vary dependant on the calcining method used and the type of fuel used?
- Are there any methods of calcining limestone that produce a pure stream of carbon dioxide from the calcination of the limestone (i.e. physically separating the calcination of the limestone from the heating (see diagram), as opposed to co-firing the fuel/air mix with the limestone in a kiln)? If so, how energy efficient are they?
If you are able to help answer any of these questions, please get in touch with us. This project cannot progress without your input.