Energetic and Economic Analysis of Spineless Cactus Biomass Production in the Brazilian Semi-arid Region

The Brazilian semi-arid region is marked by a variable spatial-temporal rainfall distribution, concentrated over a 3 to 4 month season. Limited water availability is the main obstacle to the production of forage plants of C3 metabolism (such as corn and soybeans) and C4 metabolism (such as sugarcane), as well as livestock. To mitigate this forage supply, the spineless cactus (SC) has been cultivated in the region, producing high biomass amounts in this harsh environment. Recently, this remarkable capacity to produce biomass has drawn the attention of the renewable energy sector, supported by recent studies demonstrating the feasibility of its biomass as a raw material for bioenergy production. However, before moving to commercial scale, it is necessary to demonstrate that large-scale production has energy and economic viability for clean energy investors. Thus, the objective of this article was to analyze the energetic and economic viability of forage cactus cultivation systems in the Brazilian semi-arid region. The data used were extracted from the literature, based on forage production. For the energy evaluation, the energy balance was performed and the energy efficiency, energy productivity, specific energy, and net energy metrics were applied. The financial feasibility analysis used the Net Present Value (NPV) and Internal Rate of Return (IRR). The energy balance revealed that the SC cultivation is viable for biomass commercial-scale production, with an energy efficiency of 3.36, an energy productivity of 0.25 kg MJ(-1), a specific energy of 13.5 MJ kg(-1), and an energy balance of 127,348 MJ ha(-1). For the economic aspect, considering an attractive minimum rate of return of 8%, production also proved to be viable, in a time horizon of three years. The Net Present Value and IRR metrics were USD 2196 and the IRR was 46%, respectively. The results found are important to encourage new investments in rural properties in the semi-arid region, and cultivation in new areas proved to be an efficient alternative from an energy and economic point of view, in addition to collaborating for the energy transition to sustainable sources and in the mitigation of regional environmental impacts.