Carbon capture in the cement industry: technologies, progress, and retrofitting

Several different carbon-capture technologies have been proposed for use in the cement industry. This paper reviews their attributes, the progress that has been made toward their commercialization, and the major challenges facing their retrofitting to existing cement plants. A technology readiness level (TRL) scale for carbon capture in the cement industry is developed. For application at cement plants, partial oxy-fuel combustion, amine scrubbing, and calcium looping are the most developed (TRL 6 being the pilot system demonstrated in relevant environment), followed by direct capture (TRL 4–5 being the component and system validation at lab-scale in a relevant environment) and full oxy-fuel combustion (TRL 4 being the component and system validation at lab-scale in a lab environment). Our review suggests that advancing to TRL 7 (demonstration in plant environment) seems to be a challenge for the industry, representing a major step up from TRL 6. The important attributes that a cement plant must have to be “carbon-capture ready” for each capture technology selection is evaluated. Common requirements are space around the preheater and precalciner section, access to CO2 transport infrastructure, and a retrofittable preheater tower. Evidence from the electricity generation sector suggests that carbon capture readiness is not always cost-effective. The similar durations of cement-plant renovation and capture-plant construction suggests that synchronizing these two actions may save considerable time and money

Financial viability of school retrofit projects for clients and ESCOs

Published by Taylor & Francis. The energy performance contracting market is potentially substantial but very little work has been undertaken to understand the characteristics of successful projects. This study uses a probabilistic analysis of four hypothetical projects in the UK schools sector under the 2014 policy regime, combined with qualitative interviews with practitioners, to explore the conditions for a viable project. It finds that the proposed approach has the potential to allow more detailed exploration of project structures and scope for creating greater understanding of likely returns and the factors affecting them. Evidence is found that the use of deterministic risk screening techniques such as simple payback results in viable opportunities being overlooked. The risk profiles for clients and contractors (energy service companies – ESCOs) are not symmetrical and they will each find different projects more attractive. The results suggest that greater consideration needs to be given to the precise risk allocation between client and contractor to ensure that likely returns are properly understood. This study demonstrates a method for exploring project characteristics that can be used to understand their impacts on the financial returns for clients and contractors

Representations of people in Urban Building Energy Models

Occupant behaviour is commonly acknowledged as a key driver for variation in building energy performance (Gaetani et al., 2016). ASHRAE (2009) notes it as an important factor in the significant discrepancy between proposed building performance and actual energy consumption. A large body of literature exists dedicated to exploring energy behaviours and the need for more holistic considerations of energy behaviours, but this has not been connected to occupant modelling in Urban Building Energy Models (UBEMs). This paper develops a framework to identify and classify representations of people in UBEMs by reviewing and connecting the behaviour change and UBEM literatures. Combined with the classification of the approaches of people’s representation, we show that schedule-based models perform better although it cannot provide a full explanation of energy practices. While agent-based approaches offer the potential to incorporate the more holistic approaches called for by Kierstead (2006) the computational burdens which result may be excessive at the urban scale. The main framework developed can provide simulation practitioners with insights into energy behaviours

A Comparative Study of Different Sorbents in the Context of Direct Air Capture (DAC): Evaluation of Key Performance Indicators and Comparisons

Direct air capture can be based on an adsorption system, and the used sorbent (chemisorbents or physisorbents) influences process. In this work, two amine-functionalized sorbents, as chemisorbents, and three different metal organic frameworks, as physisorbents, are considered and compared in terms of some key performance indicators. This was carried out by developing a mathematical model describing the adsorption and desorption stages. An independent analysis was carried out in order to verify data reported in the literature. Results show that the equilibrium loading is a critical parameter for adsorption capacity, energy consumption, and cost. The considered metal organic frameworks are characterized by a lower equilibrium loading (10−4 mol/kg) compared to chemisorbents (10−1 mol/kg). For this reason, physisorbents have higher overall energy consumptions and costs, while capturing a lower amount of carbon dioxide. A reasonable agreement is found on the basis of the operating conditions of the Climeworks company, modelling the use of the same amine cellulose-based sorbent. The same order of magnitude is found for total costs (751 USD/tonneCO2 for our analysis, compared to the value of 600 USD/tonneCO2 proposed by this company)