Implications of land class and environmental factors on life cycle GHG emissions of Miscanthus as a bioenergy feedstock

Abstract

Replacement of fossil fuels with sustainably produced biomass crops for energy purposes has the potential to make progress in addressing climate change concerns, nonrenewable resource use, and energy security. The perennial grass Miscanthus is a dedicated energy crop candidate being field tested in Ontario, Canada, and elsewhere. Miscanthus could potentially be grown in areas of the province that differ substantially in terms of agricultural land class, environmental factors and current land use. These differences could significantly affect Miscanthus yields, input requirements, production practices, and the types of crops being displaced by Miscanthus establishment. This study assesses implications on life cycle greenhouse gas (GHG) emissions of these differences through evaluating five Miscanthus production scenarios within the Ontario context. Emissions associated with electricity generation with Miscanthus pellets in a hypothetically retrofitted coal generating station are examined. Indirect land use change impacts are not quantified but are discussed. The net life cycle emissions for Miscanthus production varied greatly among scenarios (À90-170 kg CO 2 eq per oven dry tonne of Miscanthus bales at the farm gate). In some cases, the carbon stock dynamics of the agricultural system offset the combined emissions of all other life cycle stages (i.e., production, harvest, transport, and processing of biomass). Yield and soil C of the displaced agricultural systems are key parameters affecting emissions. The systems with the highest potential to provide reductions in GHG emissions are those with high yields, or systems established on land with low soil carbon. All scenarios have substantially lower life cycle emissions (À20-190 g CO 2 eq kWh À1 ) compared with coal-generated electricity (1130 g CO 2 eq kWh À1 ). Policy development should consider the implication of land class, environmental factors, and current land use on Miscanthus production.

Steam-treated wood pellets: Environmental and financial implications relative to fossil fuels and conventional pellets for electricity generation

“…Upstream emissions (extraction of the natural gas in Alberta, processing and transport to the GS) and combustion at the GS are included in the analysis. We adapt models developed in prior studies (Zhang et al, 2010;Sanscartier et al, 2013) for this analysis. We do not consider retrofitting of the coal GS to natural gas boiler or NGCC systems in the present study.…”

An Approach to Identify the Suitable Plant Location for Miscanthus-Based Ethanol Industry: A Case Study in Ontario, Canada

“…The land suitable for field crops is further classified into two subgroups: prime (classes 1, 2 and 3) and marginal land (classes 4 and 5). Agricultural land in the northern region is not suitable for Miscanthus (Miscanthus × giganteus) cultivation because of its short growing period (frost-free days are only 100-145 days) excluded from this study [17,31]. The area of land under different classes varies from region to region and scattered throughout the regions (Table S2).…”

“…Although all classes of cultivable lands are suitable for Miscanthus, yield, production cost, and net emission from cultivation are varied depending on the land classes, crop rotation, and regions [17,31]. Consequently, four scenarios have been established for various regions (Central, Southern, Western and Eastern Ontario) ( Table 1).…”

“…The net emission from transportation varied marginally among the scenarios and locations because of the variation in distance. The carbon dynamics are noted to be dependent on the land classes, crop replacement/rotation, and biomass yield [17,31]. Consequently, the net emission would vary if different crop displacement or crop rotations were considered.…”

Are the environmental benefits of Miscanthus × giganteus suggested by early studies of this crop supported by the broader and longer‐term contemporary studies?

“…Miscanthus also produced fewer GHG emissions than oil (Wang et al ., ). A study in Canada reported that in each of five electricity generation scenarios, M. × giganteus produced fewer life‐cycle emissions (g CO 2 eq k Wh −1 ) than coal (Sanscartier et al ., ). In addition, in scenarios of high productivity or/and soils currently poor in carbon, M. × giganteus would further reduce GHG emissions by soil C accumulation.…”