Biochar-based bioenergy and its environmental impact in Northwestern Ontario Canada: A review

Krish Homagain · Chander Shahi · Nancy Luckai · Mahadev Sharma

REVIEW ARTICLE

Biochar-based bioenergy and its environmental impact in Northwestern Ontario Canada: A review

Krish Homagain · Chander Shahi · Nancy Luckai · Mahadev Sharma

Received: 2014-01-23; Accepted: 2014-05-19

© Northeast Forestry University and Springer-Verlag Berlin Heidelberg 2014

Biochar is normally produced as a by-product of bioenergy. However, if biochar is produced as a co-product with bioenergy from sustainably managed forests and used for soil amendment, it could provide a carbon neutral or even carbon negative solution for current environmental degradation problems. In this paper, we present a comprehensive review of biochar production as a co-product of bioenergy and its implications. We focus on biochar production with reference to biomass availability and sustainability and on biochar utilization for its soil amendment and greenhouse gas emissions reduction properties. Past studies confirm that northwestern Ontario has a sustainable and sufficient supply of biomass feedstock that can be used to produce bioenergy, with biochar as a co-product that can replace fossil fuel consumption, increase soil productivity and sequester carbon in the long run. For the next step, we recommend that comprehensive life cycle assessment of biochar-based bioenergy production, from raw material collection to biochar application, with an extensive economic assessment is necessary for making this technology commercially viable in northwestern Ontario.

biomass, life cycle assessment, LCA, CO2, carbon sequestration, greenhouse gas emissions, soil amendment.

Introduction

The earth has sustained hazardous and rapid climate change patterns due to anthropogenic carbon dioxide (CO2) emissions that have been rising by more than 3% annually since 2000 (Solomon et al. 2009; Raupach et al. 2007). Climate change and global warming have been among the most important and widely debated issues for the last decade and will continue to be so for many years to come. Anthropogenic CO2is responsible for about 25% of the total greenhouse gas (GHG) emissions in the atmosphere (Cherubini and Stromman 2011), and its current global level (385ppm of CO2) has already exceeded the safe limit (350ppm of CO2) for human beings (Rockstrom et al. 2009). As a result, global environmental changes including severe weather events (like flood and drought) and land degradation have posed immediate threats to biodiversity and productivity at the same time that demands for food and energy are increasing worldwide (Eriksen et al. 2009). The International Energy Agency predicts that world demand for energy will double by 2035 (IEA 2012). At present, most of the energy demand is being met through the use of non-renewable energy sources (e.g. fossil fuels), which are in fact the most significant contributors of GHG emissions.

Canada is one of the highest energy using countries per capita (16,800 kWh household-1year-1), next only to Iceland and Norway (Nepal et al. 2012). About 15% of this energy is being generated by coal-fired generating stations, which are responsible for 11% of Canada's total GHG emissions and 77% of GHG emissions from the heat and electricity sector alone (EC 2011). In the province of Ontario, coal fired power generating stations working at 10% of the installed capacity meet 2.7% of the total energy demand (IESO 2013), but produce more than 50% of GHG emissions from the electricity sector (EC 2012). In order to reduce the GHG emissions from coal-fired power generating stations, the Ontario Government decided to replace coal with biomass as a feedstock by the end of 2014 (MOE 2010, MOE 2010a). Ontario Power Generation's (OPG) Atikokan GeneratingStation (AGS) in northwestern Ontario is being converted to use 100% wood pellet feedstock using forest biomass. The converted AGS with an installed capacity of 230 megawatts will be the largest (Basso et al. 2013) 100% biomass fueled power plant in North America (OPG 2012) requiring about 90,000 tonnes of wood pellets annually. The converted AGS plant will supply renewable energy, on demand peak capacity power, and create about 200 jobs. Therefore, the use of woody biomass feedstock for power generation not only has the potential to address the environmental problems related to air pollution and climate change but also ensures energy security for local communities (BioCAP 2008). However, concerns have been raised about the sustainability of the supply of woody biomass to AGS and other power generating stations, without causing any negative environmental impacts.

Productive forest on Ontario Crown land in the managed forest area (Area of Undertaking or AOU) covers about 26.2 million hectares with a significant portion located within the boreal. About 18.8 million hectares of this area are eligible for forest management activities. Studies on forest based fibre availability suggest that Ontario has enough surplus biomass available (Wood and Layzell 2003; OPG 2011) to meet the AGS’s requirements. There are 18 actively operating forest management units in northwestern Ontario, capable of supplying about 2.1 million green tonnes (gt) of forest harvest residues and 7.6 million gt of underutilized woody biomass for bioenergy production; these numbers are based on an average annual forest depletion rate of 0.6% of the total productive forest area (Alam et al. 2012). This amount is more than enough to produce the 90,000 tonnes of wood pellets annually required for AGS.

Biomass can be converted into energy (heat or electricity) or energy carriers (char, oil or gas) by different thermochemical and biochemical conversion technologies (Van-Loo and Koppejan 2008). The common thermal conversion technologies in bioenergy systems include: direct combustion, liquefaction, gasification and pyrolysis. Direct combustion, where the biomass is burnt to produce heat with wood ash as a waste product, is the most commonly used complete oxidation process (Obernberger and Thek 2010). Liquefaction, or the conversion of biomass to the liquid phase (biofuel) at low temperature and high pressure (Van-Loo and Koppejan 2008), also produces a significant portion of wood ash as waste. Biomass gasification produces combustible gases including carbon monoxide, hydrogen and traces of other gasses in controlled partial combustion of biomass under high heat and pressure. Pyrolysis is a thermal degradation process producing heat, bio-oil, syngas and biochar in the absence of oxygen (Spokas et al. 2012). Biochar is a porous and stable carbon-rich co-product of the pyrolysis process that has diverse uses including soil amendments and long term carbon sequestration (Lehmann et al. 2006). Biochar differs from charcoal in the sense that it is not used as fuel. Although biochar can be produced from a variety of biomaterials in a variety of ways, in this paper we refer only to biochar produced from woody biomass in a bioenergy plant. Biochar is commonly produced using slow pyrolysis techniques based on heating rate and duration. Slow pyrolysis at 300-500℃ with a vapor residence time of 5–30 min is preferred as it maximizes the biochar production (Bruun et al. 2012; Boateng et al. 2010; Sohi et al. 2010).

Co-production of biochar with bioenergy, with its subsequent application to the soil, has been suggested as one possible method to reduce atmospheric CO2concentration (Laird 2008; Fowles 2007; Lehmann 2007; Lehmann et al. 2006). At present, there is no bioenergy production plant that uses the slow pyrolysis process for producing biochar as a co-product in Northwestern Ontario. Resolute Forest Products (Thunder Bay) burns biomass in its boiler and produces a significant amount of bottom ash, which contains varying amounts of biochar (RFP 2012).

Therefore, conversion from traditional power generation using fossil fuel to bioenergy production with biochar as a co-product can have both short and long term positive environmental impacts. Biochar-based bioenergy can reduce the rate of current GHG emissions by fixing atmospheric carbon into the soil, thereby mitigating the problem of global warming in the long term (Campbell et al. 2008). However, a comprehensive study of the potential environmental and economic impacts of bioenergy and biochar co-production in the region that includes each stage of production and utilization of the product in its life cycle needs to be conducted. Life cycle assessment (LCA, also known as life-cycle analysis or ecobalance) is a standard technique (ISO 14040: 2006 series) to assess environmental impacts associated with all stages of a product's life from cradle-to-grave (i.e., from raw material extraction through materials processing, manufacturing, distribution, use, repair and maintenance and disposal or recycling) (Afrane and Ntiamoah 2011). We could find no study documenting the LCA of biochar and bioenergy co-production in Northwestern Ontario and we suggest that this is because the necessary background information has yet to be collected. Therefore, the general purpose of this review paper is to establish the context within which such an analysis could occur. The specific objectives are to review the literature that: (1) explores biochar production potential based on biomass availability and feasibility of sustainable bioenergy production in Northwestern Ontario; (2) documents the effects of biochar on soil property and productivity; (3) examines the life cycle environmental impacts of biochar production and application in terms of GHG emissions and climate change mitigation; and (4) identifies research needs and potential environmental impact assessment methods for woody biomass utilization for biochar-based bioenergy production in Northwestern Ontario in a sustainable manner.

Methods

We conducted a thorough literature search on biochar-based bioenergy production and its environmental impacts in northwestern Ontario through ISI Web of Science and Google Scholar. Based on the search keywords (biomass, bioenergy, biochar, life cycle assessment, biochar soil amendment, Canada, Ontario and northwestern Ontario and combinations) we selected 91 peer reviewed publications (Fig. 1).

Fig. 1: Study spectrum and number of studies covered in this paper

The extent of papers reviewed is more or less global, with one third focusing on studies related to the USA (Fig. 2). Only 13 papers focused on Canada and only 6 of those were directly related to northwestern Ontario. This shows the lack of attention biochar and its environmental impact assessment has received in Canada in general and in northwestern Ontario in particular.

Fig. 2: Number of studies reviewed in different regions

Review Results

Biochar production potential in northwestern Ontario

Biochar is emerging as an important co-product of bioenergy production in Canada (Thomas 2013). Over the last decade, there has been a constant increase in the use of sawmill and harvesting residue to produce bioenergy that meets the industrial energy demand (NRCan 2010). Northwestern Ontario has a forest area of about 48 million ha of which 67% is covered by productive forests (MNR 2011). There are 18 active forest management units (FMU) in Northwestern Ontario (MNR 2012). Harvesting residue and underutilized tree species in the FMUs and sawmill waste are already being used as feedstocks in northwestern Ontario for energy generation. Studies reviewed in this paper vigorously agree that there is an abundant supply of woody biomass for sustainable bioenergy production in northwestern Ontario (Table 1). Depending upon the pyrolysis technique used, there is a possibility of producing up to 35% biochar from available woody biomass (Brick and Wisconsin 2010).

Table 1: Woody biomass availability (million tonnes year-1) in Northwestern Ontario

Biomass is widely accepted as the oldest source of energy in the world (Van-Loo and Koppejan 2008). Woody biomass, used as a primary source of energy for cooking and heating in many parts of the world, made up approximately 10% of the world’s energy use as of 2009 (Van-Loo and Koppejan 2008). Biomass combustion, responsible for over 90% of the global contribution to bioenergy, is the main technology used for bioenergy production. However, ash formation is one of the major challenges associated with biomass combustion and directly impacts the hearth, boiler or stove depending upon the feedstock (Obernberger and Thek 2010). In recent years, many technological developments, such as fast and slow pyrolysis, in the field of biochar based bioenergy production have taken place. The properties of biochar from these techniques vary with the production technique used (Table 2).

Table 2: Properties of biochar produced from fast and slow pyrolysis techniques. Fast - Moderate temperature (～6000C), short vapor residence time (＜2 sec); Slow - Low temperature (～4000C), long vapor residence time (＞30 min)

Biochar produced at high temperatures from fast pyrolysis results in lower biochar mass recovery, greater surface area, elevated pH, higher ash content, and minimal total surface charge (Novak et al. 2009). Removal of volatile compounds at high pyrolysis temperatures also results in higher percentages of carbon, and much lower hydrogen and oxygen contents (Novak et al. 2009). The properties of biochar also vary with the type of biomass used (Mohan et al. 2006). A typical analysis of average dried woody biomass yields about 52% C, 6.3% H, 40.5% O and less than 1% N. A comparison of the proximate, ultimate and elemental analysis of typical woody biomass with herabeceous plants and agricultural waste is presented in Table 3 (Tillman et al. 2009).

Table 3: Variability of different biomass feedstock composition (Tillman et al. 2009)

Biochar effects on soil properties and productivity

Biochar possesses varying amounts of nutrients including essential elements such as nitrogen, phosphorous and potassium that contribute positively to soil fertility and productivity (Table 4). Properties such as large surface area, micro porosity, high mechanical strength and stability contribute positively to soil texture and fertility of the land (Waters et al. 2011).Biochar application, as a soil enhancer, increases initial growth and crop productivity in tropical soils (Sohi et al. 2010). The growth of organisms involved in N cycling in the soil, specifically those that decrease the flux of N2O, improves with biochar application, thereby resulting in decreased plant pathogens (Anderson et al. 2011). Biochar also influences mycorrhizal abundance by altering soil physico-chemical properties (Smith et al. 2010; Zimmerman 2010), and detoxifying allelochemicals, which provide refuge from fungal grazers (Warnock et al. 2007).

Table 4: Nutrient content of selected biochars [Modified from (Waters et al. 2011)]

Reports of the effects of biochar application on soil quality and crop productivity are highly variable in the literature. High yield improvements (up to 300%) were noticed in some studies when biochar was applied to soils of low fertility (Koide et al. 2011; Kookana et al. 2011; Mankasingh et al. 2011; Sparkes and Stoutjesdijk 2011; Sohi et al. 2010; Van Zwieten et al. 2010; Laird et al. 2010; Sohi et al. 2009; Chan et al. 2007; Lehmann and Rondon 2006), whereas soils of temperate climates and of generally higher fertility showed modest biomass production improvements in the range of 4−20% (Laird et al. 2010; Husk and Major 2010). The forage value of mixed species grown on soil with biochar application (3.9 t·ha-1for 3 years) was also found to be greater than in un-amended soil (Husk and Major 2010). The increase in forage quality was followed by an increase in cow milk production (44% increase) and animal biomass production (Major et al. 2010a). Sohi et al. (2009) provide a comprehensive review of the impact of biochar application on crop yield (Table 5).

Table 5: Impact of biochar application on crop yield [Modified from Sohi et al. (2009)]

Some studies also attribute changes in N immobilization to biochar application (Kookana et al. 2011; Blackwell et al. 2010; Asai et al. 2009) but this phenomenon is of relatively short duration while the unstable fraction of biochar is decomposed. Kishimoto and Sugiura (1985) found 37% and 71% lower soybean yields with biochar application of 5 and 15 tonne per hectare (t·ha-1) respectively, and attributed this reduction to the rise in pH, which led to micronutrient deficiencies induced by the biochar application. In a 2-year trial, Gaskin et al. (2008) observed lower corn yields with peanut hull biochar applied at 22 t·ha-1compared to the control under fertilized conditions. With pine chip biochar application, yield reductions occurred at both 11 and 22 t.ha-1of biochar application in the first but not the second year of the trial. However, trials in both years were affected by drought. The interaction of biochar application with fertilizer rate and type as well as inoculation with mycorrhizae is also complex and not yet well understood (Blackwell et al. 2010).

Biochar application benefits are not only limited to increased production of biomass and crop yield in the short term. Its long term impacts on plant soil systems, nutrient cycling, climate change and mitigation have also been documented (Waters et al. 2011). A summary of significant impacts on ecosystem function is presented in Table 6.

Biochar applications monitored over several years in agricultural lands have shown many short and long term positive effects, such as a liming effect and improved water holding capacity of the soil along with improved crop nutrient availability (Jeffery et al. 2011; Kookana et al. 2011; Scheer 2011; Sohi et al. 2010; Van Zwieten et al. 2010; Major et al. 2010b; Sohi et al. 2009). Because of the variability of biochar applied and the soil types used in these studies, it is difficult to recommend biochar application as a soil amendment for all soil types and cropping systems. More field trials are required on several sites assessing the effect of biochar application in combination with other produc-tion factors.

Table 6: Summary of ecosystem benefits of biochar application (Waters et al. 2011)

Environmental impacts and life cycle assessment of Biochar

Soil carbon is one of the major sources of GHG emissions (Lal 2007). Carbon Dioxide (CO2), Methane (CH4) and Nitrous Oxide (N2O) are the most prevalent GHGs in the atmosphere and these three gases together make up about 99% of GHGs (EC 2011). In addition to the potential long term soil carbon sequestration value, biochar application also provides considerable greenhouse gas mitigation benefit by reducing N2O emissions over time (Table 7). The extent of this reduction, however, depends on soil type, application rate, soil moisture content, and biochar type (Taghizadeh-Toosi et al. 2012; Park et al. 2011; Sparkes and Stoutjesdijk 2011; Waters et al. 2011; Sohi et al. 2009). However, in some studies, neutral to slight increases of emissions of N2O from soil were observed in the short term (Clough and Condron 2010). N2O, produced as a result of microbial processes of nitrification and denitrification, has high global warming potential and contributes more than 8% to global GHGs (Harter et al. 2014). The exact mechanisms for observed effects of biochar application on N2O emissions remain unknown (Van Zwieten et al. 2010). The effectiveness of biochar application in reducing soil N2O emissions can increase over time because of the increased sorption capacity of biochar through oxidative reactions on large surface area (Singh et al. 2010). In a recent laboratory study of boreal charcoal (biochar) study Hart (2013) reported that increased mineralization due to the addition of biochar is short lived and likely related to the least stable component of biochar. A brief summary of the reviewed studies on environmental impacts of biochar are outlined in Table 7.

Table 7: Environmental impacts of biochar application

Another notable benefit of biochar application to soil is its ability to reduce nitrogen fertilizer requirements in agricultural systems (Waters et al. 2011). Production of one tonne of nitrogen fertilizer releases more than 3 tonnes of CO2into the atmosphere (West and Marland 2002). Biochar application can reduce the frequency and quantity of N application and subsequently lower emissions from the production of nitrogen fertilizer. In order to have a complete picture of the contribution of biochar production and utilization to GHG emissions, environmental quality, and human health, life cycle assessment (LCA) studies have been done.

LCA considers the flows of raw materials and energy across a system boundary to determine the process’ or product’s full cradle-to-grave impact (Steele et al. 2012; Roberts et al. 2010). LCA techniques have quantified all stages of bioenergy production and utilization systems to assess the environmental impact (Steele et al. 2012; Roberts et al. 2010; Fantozzi and Buratti 2010). Several recent LCA studies considering GHG emissions and carbon sequestration effects have focused on the co-production of biochar and bioenergy from slow pyrolysis of various biomass feedstocks (Hammond et al. 2011; Woolf et al. 2010; Roberts et al. 2010). These studies conclude that biocharsystems could mitigate 0.7–1.4 tonnes of CO2t-1of feedstock consumed. A review of life cycle studies with a brief finding from each study is presented in Table 8.

Table 8: Life cycle analysis studies covered in this review

Economics of biochar based bioenergy production

The economic feasibility of biochar based bioenergy production includes the comparison of cost of collection, transportation, processing of feedstock and energy generated during the pyrolysis process; and benefits obtained from the production of bioenergy and biochar as co-products (McCarl et al. 2009). The cost-benefit analysis also includes the trade-offs between economic gains and environmental and ecosystem function losses. The economics of the biochar based bioenergy system depends on the availability of advanced technology to produce and optimize the co-products based on management objectives. If long term carbon sequestration is valued above renewable energy, then more biochar should be produced in comparison to bio-oil(Palma et al. 2011). However, in order to maximize the economic outputs and beneficial outcomes, the supply chain including feedstock collection, transportation, pyrolysis plant design and operation, and product recovery need to be optimized (Moon et al. 2011; McCarl et al. 2009).

Onsite portable pyrolysis bioenergy production plants are used to reduce the transportation costs of forest biomass(McElligott et al. 2011). Portable units are economically feasible if located at stock piled sources of feedstock (McCarl et al. 2009). However, there is a low probability of a positive net present value (NPV) with portable systems as compared to stationary scenarios (Palma et al. 2011). Stationary fast pyrolysis facilities, using woody biomass feedstock, show the highest potential for profitability with a price of $87 tonne-1of biochar (Granatstein et al. 2009).The maximum revenue using woody biomass feedstock for energy production using slow pyrolysis is $0.09 kg-1and using fast pyrolysis is $0.11·kg-1(Granatstein et al. 2009). Furthermore, slow pyrolysis units will deliver net-negative emissions of greenhouse gases and revenue from C trading could make biochar production for soil application a worthy venture (Gaunt and Lehmann 2008).

The cost-effectiveness of global biochar mitigation potential using marginal abatement cost curves has been evaluated (Pratt and Moran 2010). Biochar stove and kiln projects in developing nations are more cost-effective than pyrolysis plants in developed countries, and thus could abate more fossil fuel carbon emissions (up to 1.03Gt by 2030 in Asia). Biochar based bioenergy projects are expensive, but can compete with other carbon negative technologies, depending on a range of factors including the price of carbon and significant ancillary benefits in terms of biomass productivity (Pratt and Moran 2010). One of the future economic consequences of biochar-based bioenergy may appear when there is a regulatory carbon trading mechanism such as the Carbon Trade Exchange (CTX). Assuming the existence of a carbon trading mechanism for biochar soil application, Galinato et al. (2011) estimated the economic value of biochar application on agricultural cropland for carbon sequestration and its soil amendment properties, and found that it may be profitable to apply biochar as a soil amendment if the biochar market price is low enough and/or a carbon offset market exists. These economic impact assessment studies emphasize the need for a local level accounting of all the stages of production to end use.

Research needs and potential environmental impact assessment methods

Bioenergy is being widely accepted as a green alternative to fossil fuel based energy in many parts of the world. Bioenergy with biochar as a co-product is even more promising in terms of soil amendment and emission reductions benefits. A number of bioenergy production technologies have been developed that produce biochar as a co-product. Biochar application as a soil amendment not only increases crop and biomass production, but also helps in managing waste from bioenergy generation plants that would otherwise end up in landfills. In order to make biochar-based bioenergy production more efficient, past research has identified the use of wood pellets instead of direct biomass as feedstock. Wood pellets help to reduce GHG emissions and the cost of electricity production (Fantozzi and Buratti 2010). The life cycle GHG emission reduction potential and cost efficiency of electricity production from wood pellets can reduce GHG emissions by 90%, NOxby 45−47%, and SOxby 76−81% as compared to coal and natural gas (Zhang et al. 2010). Wood pellets produced in North America and used in European countries to replace fossil fuels in electricity generation, have considerably reduced GHG emissions (Dwivedi et al. 2011). However, it is better to use wood pellets locally than to transport them over long distances, as transportation of wood pellets consumes one third of their energy content (Pa et al. 2012; Magelli et al. 2009). In addition, if wood pellets are used to replace natural gas in district heating systems, it may reduce GHG emissions by 82% and cost by 35% (Pa et al. 2011).

Notwithstanding the beneficial uses of biomass utilization for energy production, some non-governmental organizations (Schlamadinger et al. 1997) have been raising concerns about the sustainability of the system in the long run (Huang et al. 2013). In a recent report, which focuses on Ontario's biomass utilization policy, Green Peace (An international NGO on environmental advocacy) has strongly opposed the province's claim about carbon neutrality of biomass fuel and recommended that full and independent life cycle analyses of forest bioenergy projects be performed to track carbon emissions every year and take into account the “carbon payback time” of each bioenergy project (Mainville 2011). However, Ter-Mikaelian et al. (2008) state that the total forest carbon stock has increased under the current forest management in Ontario. They calculated that, if forests in Ontario are managed for energy production using wood pellets, it would take at least 28 years to theoretically achieve minimum break-even and carbon-neutral periods resulting from displacing coal with biomass feedstock, whereas the current forest age structure in Ontario has a minimum break-even period of 32 years after harvest for carbon balance (Ter-Mikaelian et al. 2011).

There are also differences of opinion in the net benefit of bioenergy production when considering competing interests in the energy sector. Most studies focus on maximization of energy production from biomass using combustion, which may compromise soil amendment and carbon sequestration benefits (Tilman et al. 2009; Lal and Pimentel 2007). Similarly, bioenergy produced from agriculture based feedstock may compete with food production (Pimentel et al. 2009; Searchinger et al. 2008), even though grain- and seed-based biofuels provide significant GHG mitigation benefits (Cherubini et al. 2009). Those competitions, in some extents, are being addressed by using transgenic woody plants especially in the production of biofuels (Tang and Tang 2014). There is an opportunity cost associated with biochar that is used for soil amendment as there is some energy lost in the carbonized biomass. For example, approximately 50% of feedstock energy is lost in the form of carbon in biochar when pyrolysis technology is used for maximizing biochar production (Roberts et al. 2010). Therefore, not all biomass can either beconverted to bioenergy or to biochar.

Most studies reviewed in this paper present the potential benefits of bioenergy or biochar in terms of GHG emissions reduction in the life cycle, but none of the studies conducted the carbon-balance and economic analysis of the whole biochar production and utilization within the system boundary. Therefore, a long term life cycle assessment is needed for the specific region of interest (e.g. northwestern Ontario) to make better decisions about the viability of any biochar production and utilization system (Hammond et al. 2011; Mckechnie et al. 2011).

Conclusions

Northwestern Ontario (Canada) has a sustainable and sufficient supply of woody biomass that can be used to produce biochar based bioenergy for household and industrial purposes. While several biochar based bioenergy plants are operating around the world, the switch to biomass based energy is relatively recent in northwestern Ontario with the AGS conversion representing a new era in large scale fuel requirements. If biochar and bioenergy are produced, they will serve two immediate functions: a) to provide fossil fuel free energy and b) to sequester stable carbon for a longer period. Biomass may be sourced from either harvesting waste or underutilized species. The former is usually piled at roadside and, if not burned in situ, returned to the site or used for fuel, its presence can inhibit regeneration for long periods of time. So called “slash piles” can also pose a fire hazard (McElligott et al. 2011). Harvesting of underutilized species or extension of harvesting to include coarse woody debris (CWD) has raised concerns about reduced soil nutrient inputs thereby altering forest site productivity (Hazlet et al. 2007, Wiebe et al. 2013). CWD also contributes to the structure, microhabitat diversity, and nutrient cycling of forests (Pedlar et al. 2002). Therefore, utilization of forest biomass may warrant a regional harvesting policy. Replacing fossil fuels with biomass for power generation would certainly change the carbon budget of the regional ecosystem, through transportation, collection, processing, and pyrolysis of biomass, and possibly, land application of biochar. However, a comprehensive life cycle analysis of the biochar-based bioenergy production, from raw material collection to biochar application, with an extensive economic assessment is necessary for future development and commercial viability of this technology. Such a study would help decision makers as they create effective bioenergy policies for the region and boost confidence of potential investors to start up new businesses in the area. Future research work in the area of bioenergy production should focus on transportation, storage and processing of biomass, which could further improve the knowledge base in this area.

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DOI 10.1007/s11676-014-0522-6

The online version is available at http://www.link.springer.com

Faculty of Natural Resources Management, Lakehead University, 955

Oliver Road, Thunder Bay, ON, Canada P7B 5E1.

E-mail: khomagai@lakeheadu.ca; Tel.: (807) 343 8665

Chander Shahi, Nancy Luckai

Faculty of Natural Resources Management, Lakehead University, 955 Oliver Road, Thunder Bay, ON, Canada P7B 5E1.

Mahadev Sharma

Ministry of Natural Resources, Ontario Forest Research Institute (OFRI), 1235 Queen St E, Sault Ste. Marie, ON, Canada P6A 2E5.

Corresponding editor: Chai Ruihai