Relationship between power plant efficiency and capacity and tons biomass required and acres required

Questions or comments about this information may be directed to Lynn Wright at wrightll@ornl.gov.
Yield & efficiency effect on tons/MW required at 80% capacity Yield & efficiency effect on tons/MWrequired at 90% capacity
Power plant capacity 80% 80% 80% 80% 90% 90% 90% 90%
Power plant efficiency 25% 30% 35% 40% 25% 30% 35% 40%
Annual dry tons biomass/MW 5930 4941 4235 3706 6671 5559 4765 4169
                 
Annual dry tons biomass
(dt/ac/yr) 		Growing acres required
per MW
1 5930 4941 4235 3706 6671 5559 4765 4169
2 2965 2471 2118 1853 3335 2780 2382 2085
3 1977 1647 1412 1235 2224 1853 1588 1390
4 1482 1235 1059 927 1668 1390 1191 1042
5 1186 988 847 741 1334 1112 953 834
6 988 824 706 618 1112 927 794 695
7 847 706 605 529 953 794 681 596
8 741 618 529 463 834 695 596 521
9 659 549 471 412 741 618 529 463
10 593 494 424 371 667 556 476 417

Notes:

  • Raw numbers have been used in the above table.
     
  • Calculations assume dry biomass at 8500 btu/lb = 19.75 Gj/MG and 3413 btu/kWH = 0.0036 Gj/kWh.
     
  • Rule of thumb relationship of 1000 acres and 5000 dry tons per MW is based on 80% capacity, 30% efficiency, and 5 dt/ac/yr yield.
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  • A good program goal would be to have a relationship of 500 acres and 4200 dry tons per MW at 90% capacity, 40% efficiency, and 8 dt/ac/yr yield.
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  • Yields 1-2 dt/ac/yr are common for natural forests but could also represent residue levels available from high yield plantations.
     
  • Yields 3-4 dt/ac/yr are common for pulpwood pine plantations.
     
  • Yields 4-7 dt/ac/yr are being observed in woody crop and herbaceous crop plantings without irrigation, 5dt/ac/yr still best average estimate.
     
  • Yields 7-10 dt/ac/yr are being observed in some energy crop plantings with best clones or varieties and/or with irrigation or high water tables.
     
  • Total planted area or growing area required to supply a biomass facility should be used rather than area actually being harvested in any given year. While these are the same for a herbaceous crop harvested annually, they differ significantly for a woody crop harvested once every few years. Calculation of the annual harvested area for a wood crop requires knowing both the yield (dt/ac/yr) and the harvest age of the woody crop. This varies from project to project.