Energy and Nutrient Recovery Potential from the Norwegian Food Supply System: Potensial for energi- og næringsstoffgjenvinning i det norske matproduksjonssystemet
Agricultural and food supply systems are inefficient as evidenced by poor utilization of phosphorous (P), large losses of energy and sizeable and distributed losses of food (Wirsenius 2003; Cordell et al. 2011). Researchers have identified the need for a restructuring of the agricultural system, however, proposals for the optimal system are highly dependent on specialized interests, such as food security, nutrient efficiency or energy production (Wirsenius 2003; Schmid Neset et al. 2008; Jansa et al. 2010; Cordell et al. 2012). Regarding systemic changes, the disconnect between researchers addressing their compartmentalized issues could result in problem shifting. For example, a system optimized for energy production could accelerate nutrient depletion and/or increase nutrient pollution. In terms of evaluating solutions for secondary biomass utilization, the Norwegian Ministry of Environment has stated energy production as the priority (Miljødirektoratet 2013). Renewable energy sources are needed but the lack of concurrent consideration of issues like nutrient depletion is a strong concern. Norway has existing access to renewable energy in the form of hydropower, but lacks any domestic supply of P, which is a limited resource.
There has yet to be published a Material Flow Analysis (MFA) that incorporates multiple layers to evaluate the energy and nutrient perspectives in an agricultural system. This report used MFA to evaluate the Norwegian agricultural system in terms of dry matter, energy and phosphorous. The goal of this modeling was to identify synergies and overlaps between the ideal systems for P and energy optimization. This report aimed to improve the theoretical foundation upon which initiatives and policies are built, in order to ensure that the most advantageous leverage points are used for maximum efficiency. A baseline model was constructed with the three aforementioned layers. The agricultural system was modelled from domestic production through to post consumer waste collection. Following from this baseline, three scenarios were tested and the impacts on the P and energy system compared. Important indicators in the P layer proved to be fertilizer imported, the P incinerated, the P accumulation in soils. In the energy layer focus was placed on process energy use and energy production, as well as examining large sources of loss from the system.
The results indicate that Norway is not very food secure and is highly reliant on imports of phosphorous fertilizer for the food that is grown domestically. The Norwegian government must recognize the relative impacts that the agriculture and food system have on the energy and P cycles respectively. The system modeled in this report controls nearly 100% of the P cycling within the country along with aquaculture and fisheries, yet could provide a maximum of around 11% of the nations electricity. In a country with access to hydropower, energy production should not be prioritized over phosphorous reduction, reuse and recovery.
Manure is not accepted by farmers as a source of P and is also a poor source of energy. Harvest residues, in contrast, appear to be a good source of both P and energy, without the same problems of transportation and spatial distribution. This novel and innovative multi-layered modeling successfully shed light on the inter-relations between phosphorous and energy in the Norwegian agricultural systems and contributed important preliminary results.
Place, publisher, year, edition, pages
Institutt for energi- og prosessteknikk , 2014. , 81 p.
IdentifiersURN: urn:nbn:no:ntnu:diva-25824Local ID: ntnudaim:10948OAI: oai:DiVA.org:ntnu-25824DiVA: diva2:741377
Mueller, Daniel Beat, Professor