FutureMetrics paper focuses on biomass conversions

By Katie Fletcher | December 18, 2014

In November, FutureMetrics LLC published a white paper by William Strauss on the conversion of old pulverized coal plants to use advanced solid biofuel rather than coal. The paper concludes that converting older coal plants is the lowest cost solution to renewable portfolio standard (RPS) compliance.

Advanced solid biofuel is a dense pellet shaped fuel derived from woody biomass. Just two years ago using pulverized wood pellets in large coal-fired power stations to completely replace coal was unproven, but now there are examples of power plants that are able to reliably generate the same amount of electricity as coal.

One example is the 650 MW Drax power station in the U.K., which runs on pulverized white pellets. Two other examples of conversions are by Ontario Power Generation. The OPG Atikokan 240 MW station also runs on pulverized white pellets. OPG’s Thunder Bay 310 MW station has been repurposed to use black pellets instead of coal.

Cofiring pellets with coal has also been proven at various power plants around the world. At low cofiring rates, 3 to 10 percent, pellets can be metered into coal conveyors ahead of the pulverizers with no modifications to the pulverizers or burners.

The median age of pulverized coal plants in the U.S. is 48 years. A chart in the paper shows that 77.3 percent of 428 50 MW or larger coal plants are older than 35. Plants more than 50 years old made up 44.6 percent. The paper indicated that most of the older plants were not compliant with emissions regulations for sulfur, mercury and NOx, and that the plants are facing expensive retrofits to their flue gas cleaning systems.

In the U.S. there isn’t a carbon policy to incentivize making the conversion from coal to advanced biofuel, but 27 states do have a RPS. Eleven other states have variants on RPS. The RPS is a regulation that requires utilities to use renewable energy sources for power generation, and its’ goal applies to 55 percent of retail electricity production in U.S. The white paper indicates that the proportion of renewable energy generation required by those states with RPS increases every year towards the goal that each state sets.

The paper compares various energy sources for power plants. The analysis shows that pelletized biofuel is 3.06 times more expensive than coal, although the total cost of generation with pelletized fuel is only 1.29 times higher than coal. Besides hydro, the analysis showed that pelletized biofuel is the lowest cost renewable baseload or peaking solution for power generation. The analysis also indicated because coal is more labor intensive, more jobs are created.

The paper reported for every MWh not generated by coal, on average, about 1,400 pounds of CO2 is not emitted. A 500 MW power station adds up to about 3.35 million tons per year. The report concluded that right now there is a low cost, reliable, ready to deploy, renewable solution to peaking and baseload power demand that would result in the creation of more jobs than any other power generation technology.

The full report can be downloaded on the FutureMetrics website.