# Research Trends and Future Direction for Utilization of Woody Biomass in Japan
## 7 Environmental Impact Assessment of Woody Biomass Utilization
### GHG Emission Reduction Effect of Woody Biomass Heat Utilization  
The environmental impact assessment of woody biomass heat utilization covers various facilities, with estimated GHG emission reductions ranging from 2.57 to 75.93 kg-CO2 eq/GJ (Table 11). The evaluation method for woody biomass heat utilization is essentially the same as that for power generation, but the range of variation is smaller. With the exception of Cases 1, 7, 8, 9, and 18 in Table 11, the estimated results fall within the range of 60 to 80 kg-CO2 eq/GJ. Among these, Cases 7, 8, and 9 discuss GHG emission reductions when replacing different types of fossil fuels based on the same heat utilization facility. The estimated results of these three cases were relatively small because the set heat utilization efficiency was low, at only 29%. Case 10 from the same study explored a scenario in which the heat utilization efficiency increased to 75%, resulting in a GHG emission reduction effect of 65.3 kg-CO2 eq/GJ [78]. Case 1 only calculated the GHG emission changes caused by the two processes of fuel production and equipment manufacturing without considering the energy conversion process, leading to smaller calculated values [77]. In general, compared to power generation, the GHG emission reduction brought about by woody biomass heat utilization is more stable, likely owing to its smaller scale and higher energy-conversion efficiency.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Case No.**} & \multirow{2}{*}{**Year**} & \multirow{2}{*}{**Utilization**} & \multicolumn{2}{c}{**Power**} & \multirow{2}{*}{**Method**} & \multirow{2}{*}{**Displaced Fossil**} & \multicolumn{2}{c}{**GHG Emission**} & \multirow{2}{*}{**Reference**} \\  & & & **Ceneration** & & & & **Fuel** & **Reduction** & **[kg-CO2 eq/GJ]** \\ \cline{1-1}  & & & & & & & **[kg-CO2 eq/GJ]** & \\ \hline
1 & 2013 & PG & 20 & Chip & LCA & Grid electricity & \(-\)17.29\({}^{-}\)66.63 & [73] \\
2 & 2013 & PG & 20 & Chip & LCA & Grid electricity & 34.01\({}^{-}\)117.93 & [73] \\
3 & 2013 & PG & 30 & Chip & LCA & Grid electricity & 41.82\({}^{-}\)97.86 & [73] \\
4 & 2013 & PG & 30 & Chip & LCA & Grid electricity & 76.11\({}^{-}\)131.87 & [73] \\
5 & 2018 & PG & 40 & Pellet & Energy flow & Coal & 63.61 & [76] \\
6 & 2018 & PG & 40 & Chip & Energy flow & Coal & 70.00 & [76] \\
7 & 2019 & PG & N.A. & N.A. & Substitution effects & Grid electricity & 55.06 & [55] \\
8 & 2021 & PG & 21.8 & Chip & Substitution effects & Grid electricity & 3.69 & [75] \\
9 & 2016 & CHP & N.A. & Chip & IO Analysis & Grid electricity & 202.44 & [77] \\
10 & 2021 & CHP & N.A. & Chip & Substitution effects & Grid electricity & 44.21 & [75] \\
11 & 2015 & Power Plant & N.A. & N.A. & IO Analysis & Thermal power & 25.08 & [74] \\  & Construction & N.A. & N.A. & IO Analysis & plant & 25.08 & [74] \\ \hline \hline \end{tabular}
\end{table}
Table 10: GHG emission reductions of woody biomass power generation.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Case No.**} & \multirow{2}{*}{**Year**} & \multirow{2}{*}{**Method**} & \multicolumn{2}{c}{**Heat**} & \multirow{2}{*}{**Highical**} & \multirow{2}{*}{**GHG Emission**} & \multirow{2}{*}{**Reference**} \\  & & & & **Utilization** & & & **Utilization** \\  & & & **Facilities** & & **Efficiency** & & **Fossil Fuel** & **[kg-CO2 eq/GJ]** \\ \hline
1 & 2016 & IO Analysis & Household & N.A. & Light oil & 2.57 & [77] \\
2 & 2012 & LCA & Household & N.A. & Heating oil & 60.53 & [79] \\
3 & 2012 & LCA & Household & N.A. & Heating oil & 78.65 & [79] \\
4 & 2015 & LCA & Factory & N.A. & Aerosene & 72.36 & [72] \\
5 & 2015 & LCA & City hall & N.A. & Aerosene & 79.53 & [72] \\
6 & 2015 & LCA & Household & N.A. & Aerosene & 58.58 & [80] \\ \hline \hline \end{tabular}
\end{table}
Table 11: GHG emission reductions of woody biomass heat utilization.