Contents Introduction
Fossil fuels although non-renewable and finite in are gradually diminishing. The world's available oil resources are estimated to be diminishing by approximately 29 billion barrels per year. Hence, it is anticipated that these resources will be completely depleted by 2060 [1]–[2]. Sarkar et al. [2] determined that burning fossil fuels releases approximately 21,300 Petagrams of CO2 alongside other greenhouse gases. Although natural processes are responsible for the removal of approximately 50% of these emissions, there remains a net increase of 10.65 thousand Petagrams of CO2 annually [2]. In 1998, the European Commission launched the sustainable energy strategy. It was stated that a sustainable energy system should ensure energy independence, support the patterns of economic growth and consider human health and environmental protection [3], [4]. Subsequently, there emerged a need to investigate renewable and environmentally- friendly energy sources that align with the criteria of a sustainable and emission-free economy [2]. Therefore, renewable energy sources such as biomass, which is largely agricultural products, and other biodegradable wastes are at the forefront of this revolution [5]. These resources can be converted into energy through either direct or indirect methods [6]. Agricultural products are highly beneficial as they can sequestrate CO2 [7]. The utilisation of biomass as a source of energy leads to the release of carbon dioxide (CO2) into the atmosphere. However, this CO2 is subsequently absorbed by plants during the process of photosynthesis, enabling them to produce additional biomass [8]–[10]. Biofuels are not only safe but can be utilised in different diesel engines generally without any engine change. Biodiesel production is increasingly popular due to its renewable nature and lower emissions compared to traditional diesel fuel [11]. Demirbas (2008) projected that developed countries will rely on biomass waste to fulfil approximately half of their total energy requirements by 2050. Agricultural biomass plays a crucial role in biofuel production, offering an opportunity to meet energy demands without compromising essential food resources while simultaneously minimizing waste [12]. The primary aim of this review is to provide a complete overview of past research on how biomass can be used as a clean and renewable energy option and reveal potential future research directions.
