This paper explores the possibility of utilizing Scottish agricultural waste for sustainable energy, including combined heat and power (CHP). Challenges of using unconventional agricultural feedstocks for gasification are addressed, and the study is focused on the fundamental understanding of gasification processes as well as the design constraints of a commonly used downdraft gasifier. An integrated kinetic and CHP model is presented to address these, and the results demonstrate the optimal working parameters that maximize the production of high-quality syngas and power from the CHP engine. Based on the robust sensitivity analysis, an equivalence ratio (Φ) of 0.3–0.35 with moisture content (MC) less than 10% yields higher production of syngas, thus resulting in higher gasification efficiency. Moreover, an increase in Φ also favors the gasification temperature, which promotes tar cracking and results in lower tar content. Additionally, the gasification efficiency, design limitations, and challenges are addressed to optimize the gasifier design so that it can handle diverse feedstocks with high performance. Therefore, the findings are significant in the field of bioenergy and, in particular, help to expand the route of converting agricultural waste to energy.

The influence of throat diameter and gasifying medium on gasifier performance is investigated using a CFD model. Lower throat ratios favour higher gasification efficiency, carbon conversion, and producer gas yield, with potential to reduce CO ₂ emissions by 50%.

The rapid increase in energy consumption around the world is the main challenge that compromises and affects the environment. Electricity generation, which mainly depends on fossil fuels, produces around 80% of CO₂ emissions released into the atmosphere. Renewables are a remarkable alternative for energy production. However, they are intermittent sources of energy. Liquid air energy storage (LAES) is a medium-to large-scale energy system used to store and produce energy, and recently, it could compete with other storage systems (e.g., compressed air and pumped hydro), which have geographical constraints, affect the environment, and have a lower energy density than that of LAES. However, the low efficiency, high payback periods, and profit values of LAES hamper its commercialization. LAES is premature to be fully studied because lack of actual operating conditions and results from large plants, which affect the techno-economic predictions, in turn, affecting technology commercialization. Furthermore, the off-design conditions are not fully covered although it is a crucial step in system performance evaluation. To this end, the current mini-review sheds light on the LAES design, history, types, limitations, and the associated techno-economic analysis. In addition, state-of-the-art modelling tools are widely explained with benefits and shortage. Furthermore, LAES integration with other systems is explained widely, as it was found to boost the system performance and increase the profit with lower payback periods.