Environmental life cycle assessments of producing maize, grass-clover, ryegrass and winter wheat straw for biorefinery

Abstract

The aim of this study is to assess the potential environmental impacts of producing maize, grass-clover, ryegrass, and straw from winter wheat as biomass feedstocks for biorefinery. The Life Cycle Assessment (LCA) method included the following impact categories: Global Warming Potential (GWP100), Eutrophication Potential (EP), Non-Renewable Energy use (NRE), Potential Fresh Water Ecotoxicity (PFWTox) and Potential Biodiversity Damages (PBD). The results showed that GWP100 (in kg CO2 eq, including contribution from soil carbon change) for producing 1 ton of dry matter (t DM) was highest for ryegrass, grassclover and maize, and lowest for straw. The carbon footprints of ryegrass, grass-clover and maize were affected by including the contribution from soil organic carbon (SOC) changes. Nitrous oxide emissions and emissions related to the production of agro-chemicals (including N-fertilizer) were other hotspots in the carbon footprint. The EP calculated per t DM was highest for grass-clover, ryegrass and maize, and was lowest for straw. NRE use (MJ eq/t DM) was highest for ryegrass, grass-clover and maize and lowest for straw. Major hotspots were diesel use for field operations and agro-chemicals production. The PBD, expressed as Potentially Disappeared Fraction (PDF) showed the highest adverse impact to biodiversity in maize, followed by straw, whereas the results showed relatively lower impact for ryegrass and grass-clover. The PFWTox (CTUe/t DM), at farm level was highest for straw, followed by maize, whereas the values were significantly lower for grass-clover and ryegrass. These variations in ranking of the different biomasses productions using different impact categories for environmental performance showed that it is important to consider a wider range of impact categories for assessing environmental sustainability.

Can farmers mitigate environmental impacts through combined production of food, fuel and feed? A consequential life cycle assessment of integrated mixed crop-livestock system with a green biorefinery

“…per 0.55 ha, Table 2), which was close to the values reported in Dalgaard et al (2007a). NH3 emission, as estimated per FU if was to calculated per 1 ha of land, then it would be 38 kg NH3-N, which was also within the range, as reported for a typical Danish pig farms (27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44) (Dalgaard, 2007). The calculated nitrate emissions (53 kg NO3-N per ha) was also close to the range reported for a typical Danish pig farm (63-95 kg NO3-N).…”

Environmental life cycle assessment of producing willow, alfalfa and straw from spring barley as feedstocks for bioenergy or biorefinery systems

“…PFWTox was calculated using the ILCD method (European Commission, 2012), and emission distribution fractions of the pesticides at the farm level were based on the study reported by Parajuli et al (2016). The choice of different impact assessment methods was mainly due to following two reasons: (i) to cover most of the selected impact categories by single method and (ii) to interpret the results of the life cycle impact assessment, in the expressed units of the selected impact categories, as described above.…”

“…Birkved and Hauschild (2006) suggested that emissions of pesticides to soil can occur indirectly, hence it is relevant to assess the relative emissions to air and freshwater. Parajuli et al (2016) using the tool PestLCI 2.0.6 presented the sensitivity of using different types of pesticides and varying agro-climatic parameters on the emission distribution fractions of the active ingredients. Based on their study, ecotoxicological measures were sensitive to the types of active ingredients and the season of applying the pesticides, as also coined in similar line in Dijkman et al (2012).…”

“…Phosphorus (P) losses were set to 5% of the P-surplus (Nielsen and Wenzel, 2007). The Psurplus was calculated after accounting the P-uptakes by the plants (Møller et al, 2000), as summarized in Parajuli et al (2016). The total PFWTox was calculated covering the two levels: (i) at farm level, estimating the emissions from pesticides during their application and (ii) at background level by covering the toxic emissions related to the production of the assumed material inputs entering into the agricultural system.…”

Life Cycle Assessment of Giant Miscanthus: Production on Marginal Soil with Various Fertilisation Treatments

“…Soil carbon sequestration was adopted at 9.7% of the net C input [28]. The net C input was calculated from the difference between the amount of organic matter (OM) available to giant miscanthus (digestate and crop residues) and spring barley (cultivated in a conventional tillage system) with straw incorporated into the soil (as reference) [29,30]. The number of crop residues introduced to soil was calculated in the C-TOOL model [31].…”