The growing volume of waste is one of the most important environmental questions. Renewable energy resource use for energy production increase the amount of industrial wastes. There is a progress of replacing fossil fuels by renewable energy resources. Although biomass combustion is CO2 neutral process, it creates considerable amount of bottom ashes which contributes to another environmental issue – wastes and their disposal. In Latvia 46.7 % of renewable energy sources were consumed for heat generation in boiler houses. Wood ash wastes from energy sector have a wide range of usage. In industrial sector wood ashes are used in technological processes as filters and absorbents. Wood ashes can be used like fertilizer and land supplement in agricultural sector. Building sector uses wood ashes as admixture to concrete and as component to make insulation materials. The objective of the work is to determine biomass ash physical properties according to experiment plan.