1. Introduction
“Everything should be made as simple as possible, but not simpler” (Albert Einstein)
Bioenergy is the world’s largest source of renewable energy, and it is expected to grow substantially as one of many complimentary pathways to support decarbonization initiatives to limit global warming to 1.5 °C [
1,
2]. The IEA roadmap “Net Zero by 2050” recognizes bioenergy as an essential option in the transition towards a carbon-neutral society while simultaneously contributing to the United Nations Sustainable Development Goals (SDGs) [
1].
For the European Union, bioenergy will play a crucial role in meeting the newly established binding target of integrating at least 42.5% renewable energy sources into the overall energy mix by 2030, contributing to the EU policy objective of reducing CO2 emission by at least 55% by the same year. In the current global scenario, characterized by geopolitical and energy market instability, bioenergy production is also perceived as a means for the EU to reduce its dependence on external energy supplies, thus improving the security of energy supply in the medium and long term.
In such a context, cultivating dedicated species for energy production, the so-called energy crops, will play an important role [
3]. Despite concerns about the environmental impact of energy crop expansion, mainly associated with direct and indirect land use change and food competition for resources [
4], various authors have highlighted the possibility of sustainably integrating energy crops into current farming systems. For example, this can be achieved by dedicating marginal lands [
4,
5,
6] or adopting conservation agricultural practices [
7], such as crop rotation [
8]. In this regard, Vera et al. [
4] have emphasized the importance of considering context-specific conditions in developing appropriate solutions to meet the worldwide demand for sustainable bioenergy. For this reason, researchers are increasingly focusing on optimizing the allocation of energy crops within conventional agricultural systems to minimize the competition with resources used for food production (i.e., land, water, energy); different methodologies have been proposed to aid landscape planners, policymakers, and decision-makers in the thoughtful integration of energy crops into sustainable farming projects [
9,
10,
11,
12,
13,
14,
15].
In recent years, land suitability analysis within geographic information systems (GIS-LSA) has gained popularity for determining suitable locations for energy crops [
3,
5,
16,
17,
18,
19,
20]. Considering crop needs and land characteristics, GIS-LSA assesses how well the qualities of a land unit align with the requirements of the specific land use [
21]. However, relying solely on GIS-LSA for analyzing energy crop expansion based only on crop-specific factors may overlook the broader sustainability aspects of land, water and energy resources. The challenge, known as the “land, water, and energy trilemma”, underscores the need for a comprehensive and integrated methodological framework to ensure holistic and sustainable resource management. In this framework, Viccaro et al. [
15] proposed a spatially explicit model for assessing the scale of impacts on land, water and energy inputs associated with expanding energy crop cultivation, integrating GIS-LSA with the water–energy–food nexus (WEFN) approach [
22]. Recognized by the Food and Agricultural Organization (FAO) as a valuable approach for assessing the sustainability of energy projects in agriculture [
23], the WEFN makes it possible to systematically address water–energy–food interactions and promote efficient resource use and sustainable development [
22,
24,
25]. Initially focused on water, energy and food, the approach has expanded to include broader issues, including climate change (e.g., water–energy–food–carbon nexus) [
26,
27] and land management (e.g., land–water–energy–food nexus) [
13,
28]. Among the different factors affecting the land–water–energy nexus, several authors highlight that economic aspects should not be neglected in nexus assessments [
9,
13,
15,
29]. Recently, the profitability of energy crops has not received the same attention as environmental sustainability issues, even though energy crop expansion depends on their economic feasibility even when land, water and energy resources are used efficiently. In GIS-LSA studies, different economic factors have been considered (e.g., infrastructure, equipment, labor); however, their inclusion in terms of presence/absence in land use suitability assessment for energy crops does not provide information on economic feasibility in terms of costs and benefits as a reference point for farmers.
Developed for the first time in the 1930s, cost–benefit analysis (CBA) has been widely utilized in the scientific literature to assess the cost-effectiveness of both public and private investments [
30]. In agriculture, by comparing the benefits and costs over a specified time horizon, CBA provides insights into the potential returns on investment and allows farmers to efficiently prioritize and allocate resources among competing agricultural projects or interventions [
7]. In the bioenergy context, Cozzi et al. [
31] carried out a CBA to assess the economic feasibility of Short-Rotation Forestry (SRF) in a GIS-LSA framework, and Pulighe and Pirelli [
9] did so to evaluate the sustainability of biofuel crops in a WEFN framework. In such studies, however, CBA is not spatially explicit, meaning that the spatial variability of factors affecting the economic feasibility of energy crop cultivation is not considered, particularly the spatial variability of crop productivity. While factors affecting costs (i.e., cultivation techniques) may be regarded as the same across a given area, factors influencing benefits (i.e., crop yields) usually may exhibit significant spatial variability due to specific local conditions (e.g., climate and soil conditions). This can bring about a difference in the scale of impacts on the economic feasibility of energy crops and, consequently, on their expansion potential in a given area. For instance, in Cozzi et al. [
31], the SRF potential within the study region is delineated based on lands exhibiting high suitability after a CBA; in that study, the data on crop productivity used in the CBA were sourced from the literature. In such cases, the results may lead to misleading conclusions regarding the actual potential of energy crop cultivation. Different productivity levels could exist across the area compared to those considered, resulting in either lower or higher potential than suggested, especially when only considering lands with the highest suitability levels. Excluding areas with moderate suitability levels could limit energy crop expansion. To address these limitations, Viccaro et al. [
32] implemented a site-specific approach to assess the cost-effectiveness of SRF fertigated with urban wastewater, carrying out a CBA starting from the concept of biomass productivity and water use efficiency (WUE) [
33,
34]. The productivity of SRF was spatially determined by multiplying the crop’s WUE by the water utilized by the plants. However, similarly to the previous study, the authors constrained their analysis only to lands exhibiting the highest level of suitability to mitigate investment risks. According to the FAO suitability classes [
21], only the highly suitable class (S1) presents “
Nil to minor negative economic … outcomes”; the other classes could potentially entail negative economic outcomes ranging from moderate to very high risks (see
Table A1). In such a context, a decision support tool is necessary to assist farmers in effectively allocating energy crops by considering their economic feasibility to mitigate the risk of financial loss.
Based on the above, we propose an agroecological–economic land use suitability model (AE-landUSE) that integrates cost–benefit analysis and land use suitability analysis within geographic information systems. By considering multiple criteria simultaneously (agroecological and economic ones), the model identifies suitable areas for energy crops where the investments are cost-effective. In previous studies, CBA has usually been carried out separately from GIS-LSA, resulting in different indices for decision-making. Instead, by combining CBA and GIS-LSA in a single model, AE-landUSE provides a single spatially explicit indicator that aids decision-makers in locating energy crops within the existing agricultural systems. The results are a starting point for conducting a land–water–energy nexus analysis to allocate land, water and energy resources efficiently.
The Basilicata region (Southern Italy) was chosen as a case study for testing the model, considering two energy crops, namely, (i) rapeseed (
Brassica napus L.), the main biofuel crop in Europe [
7], and (ii) cardoon (
Cynara cardunculus L.), as potential energy crops for Mediterranean environments [
35]. This paper is structured as follows: the AE-landUSE model and the case study are described in
Section 2.1 and
Section 2.2, respectively; the main results are presented and discussed in
Section 3; and final remarks and suggestions for future research are provided in
Section 4.
4. Conclusions
Bioenergy will play a key role in limiting global warming and achieving sustainable development goals, as recognized by initiatives such as the IEA roadmap “Net Zero by 2050” and the European Union’s renewable energy targets. In this context, the cultivation of dedicated energy crops emerges as a crucial strategy, prompting researchers to explore methodologies for integrating energy crops into agricultural systems sustainably. This paper discusses the growing popularity of land suitability analysis within geographic information systems (GIS-LSA) for identifying suitable locations for energy crops. However, it also recognizes the need for a comprehensive approach that considers broader sustainability aspects related to land management, especially in terms of economic feasibility. Farmers are willing to cultivate energy crops in the current agricultural system only with positive economic return.
Based on that, this paper proposes an innovative model called AE-landUSE, which integrates cost–benefit analysis (CBA) and land use suitability analysis within GISs. By considering both agroecological and economic criteria, the model aims to identify areas where energy crop cultivation is environmentally and economically feasible. This study applies the AE-landUSE model to the Basilicata region in Southern Italy, focusing on rapeseed and cardoon as potential energy crops by adopting data input from the literature. The results demonstrate the spatial variability in land suitability and economic feasibility, highlighting the importance of considering both factors in decision-making. Furthermore, this paper discusses a sensitivity analysis which compared the results of the AE-landUSE model with and without considering land suitability. The analysis revealed significant differences in the potential for energy crop cultivation, underscoring the importance of incorporating land suitability into economic assessments to avoid overestimation and mitigate financial risks.
Overall, this paper provides valuable insights into integrating bioenergy into agricultural systems, emphasizing the need for a holistic approach that balances environmental sustainability with economic viability. In site-specific analysis, more accurate data inputs are recommended. The proposed AE-landUSE model represents a promising tool for guiding decision-makers in allocating resources effectively and promoting sustainable energy crop cultivation.