Wood-based biochars were used as microbial fuel cell electrodes to significantly reduce cost and carbon footprint. The biochar was made using forestry residue (BCc) and compressed milling residue (BCp). Side-by-side comparison show the specific area of BCp (469.9 m(2) g (1)) and BCc (428.6 cm(2) g (1)) is lower than granular activated carbon (GAC) (1247.8 m(2) g (1)) but higher than graphite granule (GG) (0.44 m(2) g (1)). Both biochars showed power outputs of 532 +/- 18 mWm (2) (BCp) and 457 +/- 20 mWm (2) (BCc), comparable with GAC (674 +/- 10 mWm (2)) and GG (566 +/- 5mW m (2)). However, lower material expenses made their power output cost 17-35 US$ W (1), 90% cheaper than GAC (402 US$ W (1)) or GG (392 US$ W (1)). Biochar from waste also reduced the energy and carbon footprint associated with electrode manufacturing and the disposal of which could have additional agronomic benefits. (C) 2014 Elsevier Ltd. All rights reserved.