Life cycle assessment of first-generation biofuels using a nitrogen crop model

Energy, economic, and environmental (3E) assessment of the major greenhouse crops: MFCA-LCA approach

In order to develop sustainable production of greenhouse crops, the economic, energy, and environmental aspects of production should be considered. The purpose of this study was to evaluate the economic, energy, and environmental (3E) sustainability of cucumber, tomato, and bell pepper production in greenhouses by performing material flow cost accounting (MFCA) and life cycle assessment (LCA) material and methods. Calculating the economic and energy value of losses in agricultural sustainability assessment studies is not common. Using the LCA method alone does not allow us to calculate the monetary and energy value of waste. If this method is used simultaneously with MFCA, this gap will be filled. The system boundary for LCA was from cradle to farm, and for MFCA, foreground processes were considered. The production of each crop was compared at the level of 1000 m2 during 1 year. Data were collected through questionnaire-based interviews. The gross value of production for cucumber, tomato, and bell pepper were 8982, 16387, and 17610 $/1000 m2, respectively. The negative production of cucumber, tomato, and bell pepper were 702, 718, and 449 $/1000 m2, respectively. The benefit-to-cost ratio in the production of cucumber, tomato, and bell pepper was calculated as 2.8, 5.17, and 5.8, respectively. The economic productivity in the production of cucumber, tomato, and bell pepper was calculated at 10.25, 7, and 4.4 kg/$. Labor cost was the main cost in the production of all three crops. The total input energy for the production of cucumber, tomato, and bell pepper was estimated to be 99.4, 123.1, and 164.6 GJ/1000 m2, respectively. Negative products in the production of cucumber, tomato, and bell pepper were obtained at - 24.2, - 23.9, and - 13.5 GJ/1000 m2, respectively. The energy productivity of cucumber, tomato, and bell pepper was calculated as 0.23, 0.26, and 0.08 kg/MJ, respectively. The specific energy indices were 4.32, 3.79, and 12.20 MJ/kg for cucumber, tomato, and bell pepper, respectively. The energy ratio in the production of tomato (0.02) was higher than bell pepper (- 0.02) and cucumber (- 0.06). From the perspective of energy, electricity was recognized as the hotspot for the production of three crops. Global warming (GWP100a), ozone layer depletion (ODP), acidification (AC), and eutrophication (EP) indices were calculated for all three crops. Tomato production was ranked first in all impact categories. On-farm emissions and electricity consumption were identified as environmental hotspots. The subsidized price of electricity, natural gas, and chemical fertilizers has led to their excessive use in the production of greenhouse plants. It can be concluded that bell pepper has the best performance from an economic point of view. However, its production is not justified in terms of energy. Tomato was ranked first in terms of energy, and cucumber was ranked first in terms of low environmental impacts. The production of these plants with energy and chemical fertilizer subsidies is currently cost-effective. If the prices are corrected, the production of these plants will face serious challenges. Producing electricity from sunlight and mechanizing production processes can be a solution to these challenges.

Nitrogen in Life Cycle Assessment (LCA) of agricultural crop production systems: Comparative analysis of regionalization approaches

Assessing reactive nitrogen (N_r) flows resulting from agricultural crop production systems (ACPS) with LCA requires regionalization. However, methodological approaches for regionalized LCA of ACPS may not necessarily reflect a comprehensive picture of N_r compounds and their complex interaction with the environment. This study presents a comprehensive analysis of the consideration of N_r in methodological approaches for regionalized LCA applied to ACPS. We conducted a review comprehending scientific literature on regionalization approaches applied to ACPS and compared these with general requirements of LCA and the scientific background of the N-cycle following the LCA framework. Special focus was placed on the analysis of process-based models (PBM) and life cycle impact assessment (LCIA) methods. We derived key factors relevant for a regional assessment of N flows in LCA and compared these to 23 regionalization approaches applied to ACPS. Main obstacles identified to conduct a regionalized LCA for ACPS involved the consideration of different regional scales and thus a missing common regionalization approach suitable for ACPS. Although, N related key-factors were mainly considered by the analyzed approaches in the different LCA phases, critical points involved the consideration of N field emissions and N impact assessment. Based on these findings, practical recommendations were given. Our comprehensive review provides relevant requirements for an improved regional N assessment in regionalized LCA of ACPS and aims to present a realistic picture when comparing different alternatives considering N specific regional impacts.

Environmental sustainability of biofuels: a review

Biofuels are being promoted as a low-carbon alternative to fossil fuels as they could help to reduce greenhouse gas (GHG) emissions and the related climate change impact from transport. However, there are also concerns that their wider deployment could lead to unintended environmental consequences. Numerous life cycle assessment (LCA) studies have considered the climate change and other environmental impacts of biofuels. However, their findings are often conflicting, with a wide variation in the estimates. Thus, the aim of this paper is to review and analyse the latest available evidence to provide a greater clarity and understanding of the environmental impacts of different liquid biofuels. It is evident from the review that the outcomes of LCA studies are highly situational and dependent on many factors, including the type of feedstock, production routes, data variations and methodological choices. Despite this, the existing evidence suggests that, if no land-use change (LUC) is involved, first-generation biofuels can-on average-have lower GHG emissions than fossil fuels, but the reductions for most feedstocks are insufficient to meet the GHG savings required by the EU Renewable Energy Directive (RED). However, second-generation biofuels have, in general, a greater potential to reduce the emissions, provided there is no LUC. Third-generation biofuels do not represent a feasible option at present state of development as their GHG emissions are higher than those from fossil fuels. As also discussed in the paper, several studies show that reductions in GHG emissions from biofuels are achieved at the expense of other impacts, such as acidification, eutrophication, water footprint and biodiversity loss. The paper also investigates the key methodological aspects and sources of uncertainty in the LCA of biofuels and provides recommendations to address these issues.

An Integrated Approach to a Nitrogen Use Efficiency (NUE) Indicator for the Food Production–Consumption Chain

Reducing nitrogen pollution across the food chain requires the use of clear and comprehensive indicators to track and manage losses. The challenge is to derive an easy-to-use robust nitrogen use efficiency (NUE) indicator for entire food systems to help support policy development, monitor progress and inform consumers. Based on a comparison of four approaches to NUE (life cycle analysis, nitrogen footprint, nitrogen budget, and environmental impact assessment), we propose an indicator for broader application at the national scale: The whole food chain (NUEFC), which is defined as the ratio of the protein (expressed as nitrogen) available for human consumption to the (newly fixed and imported) nitrogen input to the food system. The NUEFC was calculated for a set of European countries between 1980 and 2011. A large variation in NUEFC was observed within countries in Europe, ranging from 10% in Ireland to 40% in Italy in 2008. The NUEFC can be used to identify factors that influence it (e.g., the share of biological nitrogen fixation (BNF) in new nitrogen, the imported and exported products and the consumption), which can be used to propose potential improvements on the national scale.

The influence of fertiliser and pesticide emissions model on life cycle assessment of agricultural products: The case of Danish and Italian barley

Barley is an ancient crop and a great source of nutrients. It is the third largest agricultural commodity produced in Denmark and represents a relevant crop in Italy too. Due to the increasing customers awareness of sustainability issues, it has become essential to evaluate the environmental impact and the use of resources in food production and distribution systems. However, especially in agriculture, difficulties are encountered when emissions from fertilisers and pesticides need to be modelled, due to a variety of modelling options and their dependency on the availability of site-specific information. How to address these difficulties might affect the results reliability. Hence, this study aims to evaluate, using the life cycle assessment (LCA) methodology, the influence of different models for estimating emissions from fertilisers and pesticides on the environmental impacts of barley cultivation in Denmark and Italy. Two models for fertilisers and pesticides' emissions have been applied; these differ on the extent of data requirements and complexity of calculation algorithms, which might increase the results accuracy and robustness. The results show that the modelling options do affect the environmental impacts of barley production, in particular climate change, eutrophication categories, acidification and freshwater eco-toxicity. This study estimates that the variations for such categories range from 15% in the case of climate change to 89% in the case of marine eutrophication. These findings highlight the importance of the emission modelling options as well as the constraints of data requirements, critical aspects when a LCA study on agricultural products is carried out.

Product vs corporate carbon footprint: Some methodological issues. A case study and review on the wine sector

Carbon footprint (CF) is nowadays one of the most widely used environmental indicators. The scope of the CF assessment could be corporate (when all production processes of a company are evaluated, together with upstream and downstream processes following a life cycle approach) or product (when one of the products is evaluated throughout its life cycle). Our hypothesis was that usually product CF studies (PCF) collect corporate data, because it is easier for companies to obtain them than product data. Six main methodological issues to take into account when collecting corporate data to be used for PCF studies were postulated and discussed in the present paper: fugitive emissions, credits from waste recycling, use of "equivalent factors", reference flow definition, accumulation and allocation of corporate values to minor products. A big project with 18 wineries, being wine one of the most important agri-food products assessed through CF methodologies, was used to study and to exemplify these 6 methodological issues. One of the main conclusions was that indeed, it is possible to collect corporate inventory data in a per year basis to perform a PCF, but having in mind the 6 methodological issues described here. In the literature, most of the papers are presenting their results as a PCF, while they collected company data and obtained, in fact, a "key performance indicator" (ie., CO₂eq emissions per unit of product produced), which is then used as a product environmental impact figure. The methodology discussed in this paper for the wine case study is widely applicable to any other product or industrial activity.

Improved Environmental Life Cycle Assessment of Crop Production at the Catchment Scale via a Process-Based Nitrogen Simulation Model

One of the major challenges in environmental life cycle assessment (LCA) of crop production is the nonlinearity between nitrogen (N) fertilizer inputs and on-site N emissions resulting from complex biogeochemical processes. A few studies have addressed this nonlinearity by combining process-based N simulation models with LCA, but none accounted for nitrate (NO3(-)) flows across fields. In this study, we present a new method, TNT2-LCA, that couples the topography-based simulation of nitrogen transfer and transformation (TNT2) model with LCA, and compare the new method with a current LCA method based on a French life cycle inventory database. Application of the two methods to a case study of crop production in a catchment in France showed that, compared to the current method, TNT2-LCA allows delineation of more appropriate temporal limits when developing data for on-site N emissions associated with specific crops in this catchment. It also improves estimates of NO3(-) emissions by better consideration of agricultural practices, soil-climatic conditions, and spatial interactions of NO3(-) flows across fields, and by providing predicted crop yield. The new method presented in this study provides improved LCA of crop production at the catchment scale.