Forest waste contaminant removal for conversion into clean fuel for coal-fired power plants

Utility companies have made huge investments in large capacity coal-fired power plants. The political winds are shifting, however, resulting in more and more pressure on utilities to reduce reliance on the use of coal with its resulting CO2 greenhouse gas missions. These utility companies potentially face losing the ability to continue operating these plants, along with the dependable and economically available base-load energy source that coal provides. HM3 Energy has developed an innovative (T-Wood) process using torrefaction to convert forest waste woody biomass into dry and dense briquettes suitable for use as a clean fuel replacement for coal at existing coal-fired power plants. In order to stay competitive in cost with coal, we have developed our process using forest waste - the diseased and insect-damaged timber, smaller trees, tree limbs, branches, and other biomass debris from logging, thinning, and other forest activities, which have no commercial value. Unlike most woody biomass pellets and briquettes produced from wood chips, our torrefied briquettes can be used in coal-fired power plants without any plant modifications, because they behave just like coal; i.e., they can be stored outdoors, are easily pulverized just like coal, and their heating value is similar to that of coal. However, forest waste typically contains a lot of contamination, including dirt, sand, rocks, and metals. When co-fired with coal, these contaminants can contribute to severe slagging and fouling of the furnace, causing its efficiency to drop. Also, the abrasiveness caused by these contaminants will shorten the life of pelletizing die quite substantially. To minimize production and transportation costs we must produce the torrefied pellets/briquettes close to where the forest waste is gathered, but where water is usually unavailable to wash out impurities. We propose to develop an innovative, economical method of reducing the amount of soil in gathered forest waste without using water so that the soil content is less than 1% dry weight. With this soil contaminant removal method in place, we will be able to produce dense clean fuel briquettes near the source of the forest waste. This method, combined with the use of transportable production modules, will help reduce transportation costs, and therefore, the selling cost of the briquettes. As a result, the forest waste briquettes should be cost competitive to coal and much more attractive to coal-fired plants as a clean fuel replacement for coal.