Norway is working towards a low-emission society and its agriculture is in demand to contribute by reducing greenhouse gas emissions from food and feed production. There are two areas which may be considered as “low-hanging fruits”: the reduction of emissions from diesel-driven tractor work and from inefficient use of nitrogen fertilizer. The SolarFarm project addressed these areas by developing a concept of innovative technical solutions and methodologies, being applicable on most Norwegian farms. The concept utilizes available roof area on farm buildings for photovoltaic energy production in order to power a fleet of novel electrical machinery for a more automatized and targeted field management.
A computational farm energy system simulation model was designed for three typical Norwegian farm types (dairy, grain, pork/grain combined). The model showed that electrification of tractors and the installation of photovoltaics was technically feasible but altered the energy and storage demand of the farms differently. Charging of battery electric tractors had a large impact on the hourly peak power demand and high-power charging was crucial for maintaining operational practice at the farms, i.e. to avoid interruptions with tractor work due to charging. With an expected advance in the development of hydrogen fuel cell tractors and the production of hydrogen with on-farm electrolyzers, short-term (battery) and long-term (hydrogen) energy storage appeared to be a good choice to utilize the energy production system optimally.
Today’s battery technology has not yet reached an appropriate level of maturenes so that a replacement of a large diesel-fueled tractor with a large battery electric tractor is unrealistic due to the increased weight large battery packs impose on the vehicle. As an alternative, a shift in farm machinery composition into a fleet of smaller and lighter battery electric tractors, operating collectively at the same working width as the large diesel-fueled tractor, was successfully tested with a team of manned and unmanned vehicles. Additionally, vehicle charging was realized fully autonomously with an autonomous robotic charging station utilizing a visual guidance system to plug and unplug a standard type F electric plug into vehicles approaching the dedicated parking area.
Demand-based distribution of nitrogen fertilizer requires site-specific and updated in-season information on the plant status, a robust agronomic fertilizer distribution model, and precise application technology. A series of nitrogen response field trials in wheat and barley were performed and measurements were conducted with an unmanned aerial vehicle (UAV) along with the registration of biomass samples for plant status analyses. A UAV-based prediction model of plant status and an agronomic nitrogen fertilizer distribution model were then calibrated and tested in a realistic agricultural scenario where plant status was converted into a map of variable-rate nitrogen recommendations at a high spatial resolution of 1m2. To apply fertilizer at such a high spatial resolution, a precise liquid mineral nitrogen fertilizer applicator was developed due to lacking commercial alternatives and tested successfully. The concept showed a slight improvement in grain yield and its homogeneity as well as an improvement in grain protein content along a slightly reduced homogeneity when compared to conventional treatment.
For the overall assessments of the concept, sixteen different grain and dairy example farms were analyzed in the study, representing the majority of Norwegian agriculture systems in terms of cultivated area. Based on today’s limited effect and capability of battery electric tractors, it was concluded that a small battery electric tractor may replace only a marginal fraction of the diesel-fueled tractor work, whereas a whole fleet may conduct all field operations except grain harvesting. A life cycle assessment study revealed that the global warming potential of the production of spring wheat decreased when a small diesel-fueled tractor was replaced with a small battery electric tractor, and it further decreased when all diesel-fueled tractors were replaced with a fleet of small battery electric tractors. For other impact categories, as freshwater eutrophication, ecotoxicity and mineral resource scarcity, increased emissions were detected. A techno-economic analysis focused on the effects of phasing-out diesel consumption on a national level and showed that electrification of on-field tractor operations can be a feasible pathway to reduce tractor energy-use related emissions in the agricultural sector in Norway.
At the institutional level, IFE and NIBIO gained valuable experience and knowledge on (i) simulating optimal systems for on-farm renewable energy production and production forecasting, (ii) realizing a fleet of manned and unmanned electric farm vehicles working cooperatively as an alternative to today's use of large diesel tractors, (iii) a remote sensing based site-specific variable-rate nitrogen fertilization approach at very high accuracies to improve nitrogen use efficiency, (iv) identifying pitfalls and bottlenecks of such concepts by assessing energy aspects, sustainability, environmental, economic and policy-related potentials.
At the farm level, farmers gain relevant information on economic, environmental, agronomic and technical aspects of investing in new technologies for solar energy production, non-fossil driven farm vehicles, and precision fertilization. Farm advisors benefit from the same information when providing farmers good and updated information and advices for improved farm management.
At a regional level, the project provides examples, data and analyses highly required by politicians, to adjust their resource use and incentive programs, designed to stimulate farmers/industry actors towards a “green shift”. Further, regional energy providers may utilize the same information in their development and marketing strategies. Smaller, farm-related industry companies (e.g. smaller farm machinery producers and the increasing number of UAV-based service providers) may utilize ideas, technical solutions (prototypes) and software developed during the project, as starting points to develop new, marketable products.
At the national scale, agricultural authorities, partly in dialogue with the farmers trade union, may utilize information from the project in policy making decisions. The results from this project may be a vital part of the knowledge platform needed to fulfil the vision of a fossil free Norwegian agriculture in 2030. Large farming industry actors (e.g. those being part of Norsk Landbrukssamvirke) may benefit from the results in their continuous work on adjusting their long-term plans and strategies not only to handle a moving marked, but also to modifications in the legislative framework, partly driven by an increasing focus on the on-going global climate change. It is not possible to quantify which impact the current project will have on the national GHG-emissions, since this relies on drivers beyond the control of this project. To what extend the solutions will be taken into use, depends to a large extend on economic aspects, such as price/availability, incentive programs, taxation, etc.
Internationally, it is expected that the international, peer reviewed publications will receive attention in the research community and among product developers in large companies, which follow the research literature closely, especially that related to evolving technological solutions in the interface between agriculture and technology.
There are two areas which may be considered as 'low-hanging fruits' in terms of greenhouse gas mitigation options for food and feed production: reducing the emissions from tractor work on the farm, and reducing the emissions related to low nitrogen use efficiency. In this project, we address these two areas by developing a concept of innovative technical solutions and methodologies applicable at farm level, the SolarFarm. The SolarFarm concept is about utilizing available roof area on farm buildings for solar energy capture, and to use this energy along with state-of-the-art precision agriculture technologies to produce food and feed in a more sustainable manner. To shorten the time span from concept to implementation, SolarFarm comprises a set of approaches, ranging from relatively simple solutions, e.g. for farmers with low motivation for investing in advanced technology, to more comprehensive solutions, e.g. for farmers/early adopters devoted to technology, who want to utilize the full potential. In more detail, the concept involves energy carriers and storage capacity, tailored for the annual and highly dynamic pattern in renewable energy production and demand. It also opens for a system change in farm machinery composition, moving from one or two large and heavy diesel tractors to a few and partly unmanned electrical tractors. The concept integrates the idea of demand-based nitrogen fertilization, in which unmanned aerial vehicles for data acquisition play a central role, along with a system for steering and communication. Moreover, the concept represents a base-case for renewable energy use in a farm setting, enabling assessments of energy aspects, sustainability, environmental impact, cost-efficiency and consequences for policy-makers.
This 4-year project is an inter-disciplinary cooperation between NIBIO, IFE, two international experts, and a stakeholder group, which cover the entire knowledge-chain of the proposed research topics.