Sunday, February 28, 2010

CO2 Benefits of Biomass Energy Vs. Solar and Wind Energy (Part 3)

In Part 1 and Part 2 of this blog series on the benefits of biomass energy, we made three key points:
  • That biomass energy is carbon cycle neutral, just like solar and/or wind energy.
  • Biomass energy can be carbon cycle negative when it is developed in an environmentally sustainable way (e.g., soil building carbon sequestration, incorporating biochar).
  • Biomass energy is much more likely (especially in the Southeast and Midwest U.S.) to displace base load coal-fired electricity generation than either wind or solar power.
  • The reason for this is something called an "availability factor" (i.e., the number of hours a generating unit runs), where typically, solar and wind resources have low availability factors which are usually associated with natural gas or oil peaking and intermediate dispatch units.

    Availability or Capacity Factors by Technology

    This last point is important as coal fired power plants in the U.S. are responsible for 82% of CO2 emissions from total electricity generation.

    Today, we will summarize these 3 key points by

  • Building on the previously cited EPRI paper on the avoided CO2 intensity of fossil fuel technology options (oil, natural gas, coal).
  • Incorporating empirical research on soil carbon sequestration from growing energy crops.
  • From carbon sequestration work performed with the University of Florida on fast growing trees, we found that a volume of below ground biomass equal to ~60% of the above ground mass was being created. However, we must note that our findings of terrestrial carbon sequestration are significantly higher than found in other research. Because of this, we include carbon sequestration rates derived from a U.S. Department of Energy study performed in North Carolina in the table below -- providing a range of .24 (DOE estimate) to .64 (our research findings estimate) tons per Mwh.

    CO2 Displacement by Technology (ton/Mwh)

    CO2 Displacement by Technology (ton/Mwh)

    Conclusion: When biomass energy is developed in an environmentally sustainable way as base load power generation (displacing coal use), the CO2 benefits can be ~4 times greater than solar power displacing natural gas peaking technology.

    No comments: