1. www.REN21.net
2. www.eia.gov/forecasts/ieo/
3. IEA, Bioenergy Annu. Rep., Paris, 2012.
4. AGEE Stats, “Renewable energy sources 2012,” op. cit. note 37.
5. Biomass Co-firing: Technology Brief, Abu Dhabi: International Renewable Energy Agency (IRENA), 2013.