Ordinary Portland cement (OPC) is produced through energy-intensive processes and contributes to approximately 8% of global carbon dioxide emissions. As one of the most consumed materials after water, cement's environmental impact is substantial. Decarbonizing emissions in the intensive processes of cement production requires a sustainable supply of low-carbon resources. The purpose of this study is to explore the potential of agricultural waste ashes as supplementary cementitious materials (SCMs) to reduce the carbon footprint of OPC. In Africa, where agricultural waste is abundant, these residues could offer a sustainable solution for cement manufacturing. This study employed a multi-criteria decision analysis methodology to identify and select relevant literature for analysis. The review reveals that incorporating agricultural-based SCMs, such as rice husk ash, coffee husk ash, sugarcane bagasse ash, and palm oil fuel ash, into cement production can significantly reduce clinker requirements, thereby lowering carbon dioxide emissions while maintaining performance standards of OPC. The review found that locally sourced waste materials can reduce the carbon footprint of cement by up to 40%. Transitioning from a clinker-dependent sector to a bio-based one presents several opportunities as well as challenges for the African cement industry, but it is critical for reducing carbon emissions and improving sustainability. This approach not only decreases emissions but also supports sustainable construction, aligning with global climate goals and sustainable development goals (SDGs) 12 (responsible consumption and production) and 13 (climate action). Adopting green cement could revolutionize the African cement industry, promoting resource efficiency and sustainable development across the continent.

Energy supply for clean cooking is a priority for Sub-Saharan Africa (SSA). Liquefied petroleum gas (LPG, i.e., propane or butane or a mixture of both) is an economically efficient, cooking energy solution used by over 2.5 billion people worldwide and scaled up in numerous low- and middle-income countries (LMICs). Investigation of the technical, policy, economic and physical requirements of producing LPG from renewable feedstocks (bioLPG) finds feasibility at scale in Africa. Biogas and syngas from the circular economic repurposing of municipal solid waste and agricultural waste can be used in two groundbreaking new chemical processes (Cool LPG or Integrated Hydropyrolysis and Hydroconversion (IH²)) to selectively produce bioLPG. Evidence about the nature and scale potential of bioLPG presented in this study justifies further investment in the development of bioLPG as a fuel that can make a major contribution toward enabling an SSA green economy and universal energy access. Techno-economic assessments of five potential projects from Ghana, Kenya and Rwanda illustrate what might be possible. BioLPG technology is in the early days of development, so normal technology piloting and de-risking need to be undertaken. However, fully developed bioLPG production could greatly reduce the public and private sector investment required to significantly increase SSA clean cooking capacity.

The cement industry contributes significantly to local economies by creating jobs and supporting industries such as healthcare, education and transportation. While cement contributes to development and economic growth, it also poses serious risks to the natural environment and human health. A systematic literature review based on a bibliometric analysis was conducted. The search focused on studies related to the cement and construction industries, circular economy, sustainability approaches, and impacts of cement and concrete. A refined key word search was used to select articles from the Scopus database. This resulted in a final selection of 197 documents that fit the inclusion criteria. While most of the circular economy research studies reviewed offered technical solutions such as optimizing efficient production processes or recycling materials, there were fewer studies that examined the socio-economic and governance dimensions of circular economy practices, hence the knowledge gap. To supplement this, case studies from cement companies globally were reviewed to provide practical solutions that can facilitate the transition to circular economy practices while ensuring social justice considerations for local communities. Reviewed studies found a positive association between presence of cement plants and economic growth of local communities but negative associations between exposure to cement plants, the natural environment and human health. This review highlights the significant need to integrate socio-economic and environmental dimensions into sustainability efforts and inform policymakers about these impacts to develop long-term sustainable practices. Achieving this balance is critical to maximizing benefits and minimizing harm in local communities affected by cement production.

We investigate the potential in producing biodegradable bio-plastics to support the emergent ‘net-zero’ greenhouse gas (GHG) emissions targets in the UK. A ‘cradle to grave’ life cycle assessment was developed to evaluate GHG mitigation potentials of bio-based polybutylene succinate plastics produced from wheat straw-only (single feedstock) or wheat straw plus Miscanthus (mixed feedstocks) agricultural supply systems. For scenarios using mixed feedstocks, significant carbon mitigation potentials were identified at catchment and national levels (emission reduction of 30 kg CO₂eq kg⁻¹ plastic compared to petroleum-based alternatives), making the system studied a significant net carbon sink at marginal GHG abatement costs of £0.5–14.9 t⁻¹ CO₂eq. We show that an effective ‘net-zero’ transition of the UK’s agricultural sector needs spatially explicit, diversified and integrated cropping strategies. Such integration of perennial bio-materials into food production systems can unlock cost-effective terrestrial carbon sequestration. Research & Development and scale-up will lower costs helping deliver a sustainable bioeconomy and transition to ‘net-zero’.

Continuous incorporation of rice straw has caused significant CH₄ emissions from the paddy field production system in East China. Anaerobic digestion (AD) of the rice straw has been considered as a promising approach that could not only mitigate the land-based CH₄ emissions, but also generate low-carbon electricity and high-quality organic fertilizer. However, this approach, in many circumstances, is unable to be cost-competitive with other straw treatment processes or power sources. To understand the potential incentives that recently launched carbon trading schemes, the China Carbon Emission Trade Exchange (CCETE) and Chinese Certified Emission Reduction (CCER), could bring to the rice straw utilization value chain, we conducted a cradle-to-factory gate life cycle assessment and economic analysis of a small-scale AD system with rice straw as the main feedstock in East China. The results indicate that, depending on the choice of allocation method, the climate change impact of the bioenergy generated through the studied small-scale AD system is 0.21 to 0.28 kg CO₂eq./kWh, and the digester fertilizer produced is 6.88 to 22.09 kg CO₂eq./kg N. The economic analysis validates the financial sustainability of such small-scale AD projects with rice straw feedstock under carbon trading mechanisms. The climate mitigation potential could be achieved at the marginal reduction cost of 13.98 to −53.02 USD/t CO₂eq. in different carbon price scenarios.