There is a need to forecast greenhouse gases (GHG) emissions from usage of different biomass instead to fossil energy sources (heavy fuel oil, diesel, natural gas) to justify the decisions for heat and power production in Latvia. Help by simplified life cycle estimation method emissions of greenhouse gases was calculated for most feasible biomass technologies for heat, power or biofuels production. The investigated GHG emission savings from usage of wood, straw or straw pellets were 85 %, 93.1 % or 82.9 % compared to heavy fuel oil respectively. GHG emission savings for biogas from corn, wastewater waste, manure or municipal solid waste were 71.2 %, 84.4 %, 86.2 or 73.3 % compared to natural gas usage respectively. GHG emission savings from bioethanol production from grain or biodiesel from rapeseed were 37.5 % or 81.9 % compared to fossil diesel respectively.