Journal of Energy Bioscience 2024, Vol.15, No.2, 108-117 http://bioscipublisher.com/index.php/jeb 111 3.4 Socio-economic factors Socio-economic factors are also important in the selection of energy crops, particularly their impact on food security and rural development. The use of food crops for biofuel production can compete with food supply, raising concerns about food security. Therefore, non-food crops or crops that can grow on marginal lands are preferred to avoid this competition (González-García et al., 2013; Kocar and Civaş, 2013). Energy crops can contribute to rural development by providing alternative income sources for farmers and creating job opportunities. The cultivation of energy crops like switchgrass and Miscanthus can stimulate economic activity in rural areas (González-García et al., 2013; Zegada-Lizarazu et al., 2013). The selection of energy crops for biofuel production requires a balanced consideration of agronomic, environmental, economic, and socio-economic factors to ensure sustainability and economic viability. 4 Major Energy Crops for Biofuel Production 4.1 First generation crops First-generation biofuels are derived from food crops such as maize, sugarcane, wheat, and soybeans. These crops are primarily used for producing bioethanol and biodiesel. For instance, maize and sugarcane are extensively used for ethanol production, while soybeans and palm oil are common sources for biodiesel (Lemus and Parrish, 2009; Callegari et al., 2020). However, the use of these crops for biofuel production has been controversial due to their competition with food and feed, leading to concerns about food security and environmental sustainability (Lalman et al., 2016; Callegari et al., 2020). 4.2 Second generation crops Second-generation biofuels are produced from non-food crops and lignocellulosic biomass, which include agricultural residues, perennial grasses, and woody crops. Examples of second-generation energy crops are Miscanthus, switchgrass, reed canarygrass, and short-rotation woody crops like black locust (Lemus and Parrish, 2009; Blanco-Canqui, 2010; Vries et al., 2014; Lalman et al., 2016; Callegari et al., 2020). These crops are advantageous as they can be grown on marginal lands, reducing competition with food crops and improving soil properties by sequestering soil organic carbon (SOC) and reducing soil erosion (Blanco-Canqui, 2010; Vries et al., 2014). Additionally, second-generation biofuels have a better environmental profile, contributing more significantly to greenhouse gas (GHG) emission reductions and resource use efficiencies compared to first-generation biofuels (Scranton et al., 2015). 4.3 Third generation crops Third-generation biofuels are derived from algae, which have shown great potential due to their high yield and lower GHG footprint compared to first and second-generation biofuels (Callegari et al., 2020). Algae can be cultivated in various environments, including wastewater, and do not compete with food crops for arable land. Species like Chlamydomonas reinhardtii have been extensively studied for their biofuel production capabilities and genetic engineering potential to maximize yields (Nanda et al., 2018). Despite their promise, the production of algal biofuels still faces challenges such as high water and nutrient requirements, which need to be addressed to make them economically viable on a large scale (Nanda et al., 2018). The selection and optimization of energy crops for biofuel production involve balancing the trade-offs between food security, environmental sustainability, and economic feasibility. First-generation crops are well-established but controversial, second-generation crops offer environmental benefits and reduced competition with food crops, and third-generation crops like algae hold significant promise for the future of sustainable biofuel production (Quevedo-Amador et al., 2024) (Figure 1). 5 Optimization Strategies for Energy Crop Cultivation 5.1. Genetic engineering and crop breeding Genetic engineering and crop breeding are pivotal in enhancing the yield and resilience of energy crops. Recent advancements in genetic engineering have shown promise in increasing the biomass and lipid content of crops, which are essential for biofuel production. For instance, microalgae have been genetically modified to enhance lipid accumulation, making them a viable option for large-scale biofuel production (Rodionova et al., 2017). Additionally, the breeding of high-yielding varieties of Miscanthus and switchgrass has demonstrated significant potential in meeting biofuel demands with less land use (Femeena et al., 2018). These crops have been optimized to convert solar energy more efficiently into biomass, achieving higher yields with minimal agricultural inputs.
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