Abstract Pyrolysis is an alternative form of renewable energy production and a potential source of greenhouse gas emissions mitigation. This study examines how poplar-based biochar can be applied in Taiwan for electricity generation and for soil improvement and to what extent it brings economic and environmental benefits. It is a preliminary study and focuses on the balances of different economic and environmental items. This paper reports on a case study examination of the economic and greenhouse gas implications of pyrolysis plus biochar utilization. The case study involves using poplar grown on set-aside land in Taiwan with the biochar applied to rice fields. We examine both fast and slow forms of pyrolysis and find how the profitability varies under different price structures. The results show that fast pyrolysis is more profitable than slow pyrolysis under current electricity price, GHG price and crop yield as the slow pyrolysis generates relatively less electricity but lower value product—biochar. We also find that fast pyrolysis and slow pyrolysis offset about 1.4t and 1.57t of CO2 equivalent per ton of raw material, respectively.