The sustainability of food production systems is inherently linked with energy, water and food (EWF) resources directly and in-directly throughout their lifecycle. The understanding of the interdependencies between the three resource sectors in the context of food production can provide a measurable account for resource requirements, while meeting food security objectives. The energy, water and food Nexus tool developed by the authors has been designed to model the inter-dependency between energy, water and food resources, whilst conducting an environmental assessment of product systems. With emphasis on the inter-linkages between EWF resources, the tool quantifies material flows, natural resource and energy consumption at component unit process level. This work integrates greenhouse gas control and waste to power technologies within the energy, water and food Nexus tool and evaluates the environmental impact of a hypothetical food product system designed to deliver a perceived level of food self-sufficiency (40%) for the State of Qatar. Multiple system configurations, representative of different pathways for the delivery of consistent food products are evaluated, transforming a once linear product system into a circular design. The sub-systems added consist of a biomass integrated gasification combined cycle which recycles solid waste into useful forms of energy that can be re-used within the nexus. In addition, a carbon capture sub-system is integrated to capture and recycle CO2 from both the fossil fuel powered and the biomass integrated gasification combined cycle energy sub-systems. The integration of carbon capture with the biomass integrated gasification combined cycle transforms the carbon neutral biomass integrated gasification combined cycle process to a negative greenhouse gas emission technology known as bio-energy with carbon capture and storage. For the different scenarios and sub-system configurations considered, the global warming potential can be theoretically balanced (reduced by ∼98%) through the integration of photovoltaics, biomass integrated gasification combined cycle and carbon capture technologies. The peak global warming potential, i.e. a fully fossil fuel dependent system, is recorded at 1.73 × 10⁹ kg CO2 eq./year whilst the lowest achievable global warming potential is 2.18 × 10⁷ kg CO2 eq./year when utilising a combination of photovoltaics, carbon capture integrated with combined cycle gas turbine in addition to the integrated negative emission achieving system. The natural gas consumption is reduced by 7.8 × 10⁷ kg/year in the best case configuration, achieving a credit. In the same scenario, the photovoltaics land footprint required is calculated to a maximum of 660 ha. The maximum theoretically achievable negative emission is 1.09 × 10⁹ kg CO2/year.

Negative emission technologies such as bioenergy with carbon capture and storage (BECCS) are regarded as an option to achieve the climatic target of the Paris Agreement. However, our understanding of the realistic sustainable feasibility of the global lands for BECCS remains uncertain. In this study, we assess the impact of BECCS deployment scenarios on the land systems including land use, water resources, and ecosystem services. Specifically, we assess three land-use scenarios to achieve the total amount of 3.3 GtC year⁻¹ (annual negative emission level required for IPCC-RCP 2.6) emission reduction by growing bioenergy crops which requires huge use of global agricultural and forest lands and water. Our study shows that (1) vast conversion of food cropland into rainfed bio-crop cultivation yields a considerable loss of food production that may not be tolerable considering the population increase in the future. (2) When irrigation is applied to bio-crop production, the bioenergy crop productivity is enhanced. This suppresses the necessary area for bio-crop production to half, and saves the land for agricultural productions. However, water consumption is doubled and this may exacerbate global water stress. (3) If conversion of forest land for bioenergy crop cultivation is allowed without protecting the natural forests, large areas of tropical forest could be used for bioenergy crop production. Forest biomass and soil carbon stocks are reduced, implying degradation of the climate regulation and other ecosystem services. These results suggest that without a careful consideration of the land use for bioenergy crop production, a large-scale implementation of BECCS could negatively impact food, water and ecosystem services that are supporting fundamental human sustainability.

The goals of ensuring energy, water, food, and climate security can often conflict. Microalgae (algae) are being pursued as a feedstock for both food and fuels—primarily due to algae's high areal yield and ability to grow on non-arable land, thus avoiding common bioenergy-food tradeoffs. However, algal cultivation requires significant energy inputs that may limit potential emission reductions. We examine the tradeoffs associated with producing fuel and food from algae at the energy–food–water–climate nexus. We use the GCAM integrated assessment model to demonstrate that algal food production can promote reductions in land-use change emissions through the offset of conventional agriculture. However, fuel production, either via co-production of algal food and fuel or complete biomass conversion to fuel, is necessary to ensure long-term emission reductions, due to the high energy costs of cultivation. Cultivation of salt–water algae for food products may lead to substantial freshwater savings; but, nutrients for algae cultivation will need to be sourced from waste streams to ensure sustainability. By reducing the land demand of food production, while simultaneously enhancing food and energy security, algae can further enable the development of terrestrial bioenergy technologies including those utilizing carbon capture and storage. Our results demonstrate that large-scale algae research and commercialization efforts should focus on developing both food and energy products to achieve environmental goals.

Sustainable Development Goals (SDGs) take the global challenges into a new phase, calling for reasonable resources management from holistic perspectives. This study develops a novel integrated modelling framework for sustainable agricultural energy-water-food nexus (EWFN) management, with the objectives of maximum social welfare of water resources allocation, maximum hydroelectric generation, maximum grain crop production, maximum positive farmland ecosystem service value, and minimum negative farmland ecosystem service value. The proposed framework is capable of: (1) balancing benefit efficiency and allocation equity using social welfare function; (2) reconciling conflicting targets among socio-economic, resource, and eco-environmental spheres; (3) generating sustainable water and land resources allocation strategies considering complex and uncertain environment. The proposed model was applied to the Zhanghe Reservoir irrigation area, central China. Flexible water and land resources allocation schemes among different sectors, crops, and periods were generated, as well as managerial insights into what efforts should be done were provided for decision-makers. After optimization, efficiency-equity tradeoff was balanced with social welfare index reaching [0.94, 0.99]. Optima results show that GHGs emission contributed majority of the total loss, which cannot be totally neutralized by carbon sequestration, causing negative eco-environmental impacts of [2.3, 3.4] × 10⁸ CNY. The proposed model performs well on generating robust and coordinated solutions according to scenarios analysis and models comparison. The proposed approach has potential on achieving SDGs in agricultural EWFN system, and is portable to other agriculture-centered areas suffering from similar resources crisis.

Ecosystem restoration projects (ERPs) are effective for achieving sustainable development goals. However, a nexus perspective has not yet been effectively used to examine the regimes and interconnections between the sectors of agricultural production, ecosystem restoration, and the livelihoods of farmers, which may have constrained the efficacy of ERPs. In this study, the evolution of these different sectors in ecosystem restoration hotspot cases was investigated using a novel nexus perspective, and their interconnections and implications for ecosystem management were determined. Rapid urbanisation, reclamation, and ERPs have profoundly altered landscape patterns and caused significant ecological changes. Prior to 1999, extensive reclamation proved unsustainable because deforestation activities and cultivation on sloping cropland resulted in severe soil loss and ecosystem deterioration, despite providing significant increases in grain productivity and economic profits. Although revegetation practices after 1999 accelerated vegetation regeneration and enhanced soil retention and carbon sequestration, they also resulted in a decline in grain productivity and economic profits during the initial period of implementing ERPs (1999–2008). However, subsequent policy adjustments and the construction of terraced fields have mitigated cropland loss and maintained the grain supply. The nexus perspective was effective in identifying and coordinating relationships among the sectors, and timely policy interventions have transformed the relationships from trade-offs to synergies and provided win–win outcomes. However, the ongoing urbanisation continues to be a challenge for conserving ecosystems and ensuring food security; therefore, further optimised, and targeted strategies are required to balance contrasting goals and maximise co-benefits according to the environmental and socio-economic conditions.

Global warming, water scarcity and limited land resources are the most challenging problems facing agriculture to ensure food security for the expected 9 billion people in 2050. To solve these problems, the classical optimal planting pattern, based on crop suitability evaluation method, is often adopted to reallocate water and land resources. However, whether or not the classical optimal planting pattern, which only considers environmental conditions in crop suitability evaluation, is beneficial to the regional carbon neutrality goal and saves water and energy resources has rarely been explored. Here, China’s major arid food production area, the middle reaches of Heihe River Basin, is chosen as the demonstration to explore this issue. The classical optimal planting pattern obtained by crop suitability evaluation is compared with current planting in terms of planting distribution, carbon sequestration, energy consumption and water productivity from 2002 to 2016. Interestingly, the results indicate that optimal planting would reduce the regional net carbon sequestration capacity by up to 13.09% and increase regional carbon emissions by up to 22%, which is harmful to reach the commitment of carbon neutrality goal in China. Contrary, optimal crop planting pattern can increase regional water productivity by 1.74–32.59% and economic benefits by 1.52–30.55% while having little impact on energy consumption and water consumption. Considering the contradictions effects of classical optimal planting pattern on the food-energy-water-carbon nexus, we strongly recommend redefining the “optimal” in crop planting management by taking impacts on carbon into consideration to alleviate the crisis of global warming.

This study examines a green building retrofit plan through a system dynamics model (SDM) creating symbiosis embedded in a building-scale food-energy-water (FEW) nexus. An indicator approach was employed to exploit cross-domain seams via the use of carbon, water, and ecological footprints for sustainability, as well as food security and energy supply reliability ratio for resilience. The SDM was formulated to demonstrate a continuous stormwater treatment outflow model for rooftop farming with stormwater reuse for irrigation, nutrient cycling via the use of green sorption media, and green energy harvesting in support of rooftop farming. We prove that green energy use, stormwater reuse, and rooftop farming can lower carbon, water, and ecological footprints, avoid CO₂ emissions via carbon sequestration in rooftop farming, and improve energy supply reliability and food security. Case 1 (Base Case) includes no retrofit (current condition), Case 2 includes rooftop farming and stormwater reuse, and Case 3 incorporates additional green energy harvesting for sustaining rooftop farming. All three scenarios were assessed using a life cycle assessment (LCA) to generate water and carbon footprints. Case 3 exhibited a 2.24% reduction of total building energy demand from the utility grid due to renewable energy harvesting, while the preservation of nitrogen and phosphorus via the use of green sorption media for crop growth promoted nutrient cycling by maintaining 82% of nitrogen and 42% of phosphorus on site. The ecological footprints for the three case studies were 0.134 ha, 0.542 ha, 6.50 ha, respectively. Case 3 was selected as the best green building retrofit option through a multicriteria decision analysis.

The conventionally managed cereal-based cropping systems in the Indo-Gangetic Plains (IGP) of South Asia are energy intensive that overwhelm the farm profits and the environmental footprint. This research addresses a complex nexus between yield-energy-water-GHG footprints-economics of conservation agriculture (CA)-based intensified maize-wheat-mungbean rotation. This study evaluated the effect of long-term CA (2012–2020) with optimum nutrient management (2017–20) on energy budgeting, productivity, water and C-footprints, Water productivity (WP), and economics of the CA-based maize-wheat-mungbean system. CA-based permanent bed- and zero tillage flatbed with preceding crop residue retention were compared with the conventional till with preceding crop residue incorporation. These treatments were factored over three-nutrient management alternatives, i.e., GreenSeeker®-guided-N, site-specific nutrient management (SSNM), and recommended fertilizers' dose (Ad-hoc), were compared with farmers' fertilizers practices (FFP). Permanent bed and zero tillage treatments registered higher systems' productivity (18.2 and 12.0%), net returns (44.7 and 34.7%) and water productivity (35.6% and 22.1%), and C-sequestration (54.8 and 62.3%), respectively, over conventional till. Permanent bed- and zero tillage treatments increased the systems' net energy (NE), energy use efficiency (EUE), energy productivity (EP), and energy intensity (EI) by 22.6 and 14.0; 10.1 and 5.6; 9.7 and 5.4; 28.3 and 24.0%, respectively, over conventional till. Conventional till recorded higher net CO₂-eq emission (26.5 and 27.2%), C-footprint (20.8 and 14.5%), and water footprint (27.3 and 18.0%) than permanent bed- and zero tillage treatments. SSNM increased the system's productivity, water productivity, and energy use efficiency, while reducing the system's water- and C-footprints and net CO₂-eq emission. Thus, adopting permanent beds as a crop establishment method with SSNM could be a feasible alternative to attain higher productivity, profitability, and resource use efficiency in the maize-wheat-mungbean system in northwest India.

Securing the growing populations' demand for food energy and water whilst adapting to climate change is extremely challenging. In this regard, bioenergy coupled with carbon capture and storage or utilisation (BECCS/U) is an attractive solution for meeting both the population demand, and offsetting CO₂ emissions. The purpose of this study is to evaluate the effectiveness of BECCS/U pathways utilising CO₂ for agricultural enrichment in enhancing food systems and reducing GHG emissions within the energy, water and food nexus concept. The study bridges negative emissions with CO₂ fertilisation within an integrated system. It consists of a source of CO₂ represented by a biomass-based integrated gasification combined cycle with carbon capture, a CO₂ network for a sustainable CO₂ supply, and a CO₂ sink characterised by agricultural greenhouses. A techno-economic and environmental analysis of each of these subsystems is conducted, feeding to an overall performance analysis of the integrated BECCS/U pathway. Results reveal synergetic opportunities between the energy, water and food subsectors, whereby CO₂ is captured from an energy sub-system and is efficiently utilised to enhance food sub-systems by improving productivity and reducing crop water requirements. Thus, the proposed integrated BECCS/U system is able to improve food availability by enhancing the food system, increasing the yield by 13.8%, whilst reducing crop water requirements by 28%. System outputs resulted in a levelised cost of 0.35 $/kg of agricultural produce when the system is scaled-up, and an abatement of the related environmental burdens throughout the supply chain by achieving negative CO₂ emissions of 24.6 kg/m².year of cultivated land.