While world energy demand has certainly decreased with the beginning of the COVID-19 pandemic in 2020, the need has been significantly on the rise since 2021, all as the world’s fossil fuel resources are depleting; it is widely accepted that these resources emit greenhouse gases (GHG), which are the leading cause for the climate crisis. The main contributors to global warming are manufacturing, energy, and agriculture. The agricultural sector is composed of diversified and potential mobilizable sources of waste which can become an attractive alternative to fossil fuels for energy production, and thus sequester and use carbon. Therefore, a paradigm shift towards more sustainable energy alternatives, efficient waste management, and new technologies is necessary. One good solution is the energetic valorization of lignocellulosic biomass (LCB) which can also originate from agricultural wastes. The biomass consists of cellulose, hemicellulose, and lignin, which are sources of fermentable sugars that can be used for bioethanol production. However, the recovery of sugars requires the pretreatment of LCB before enzymatic hydrolysis, due to its inaccessible molecular structure. Different pretreatment technologies, including acid and alkaline pretreatments for selected biomasses (such as hemp, rice straw, corn straw, sugarcane bagasse, and wheat straw) are discussed and compared. Therefore, this review highlights the potential of agricultural waste as a renewable resource for energy production.