What is Biomass and how is it best used?

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Biomass is considered a renewable energy source that qualifies for carbon credits under the Kyoto Protocol. It is created with biological material derived from living or recently living plants.

Biomass can be used directly to produce thermal energy or indirectly to produce biofuel such as biogas and syngas using chemical conversion or biochemical conversion methods. USP&E Global has investigated many sources of Biomass and conversion methods with the intent of finding the highest energy yield Biomass and the best conversion technologies.

In Sierra Leone – Africa, USP&E Global investigated the use of Biomass to provide energy conversion for a 100MW Biomass Power Plant for one of its customers, London Mining Company (LMC), for which USP&E Global previously performed Engineering, Procurement and Construction (EPC) on a 13MW Heavy Fuel Oil (HFO) Power Plant. USP&E Global (doing business as USP&E Africa) is also providing on-going Operation and Maintenance (O&M) on the same LMC 13MW HFO Power Plant. LMC was interested in finding a renewable energy solution to its expanding power needs. During the Bankable Feasibility Study and related investigation USP&E was faced with three major challenges relating to Biomass energy production in Sierra Leone:

  • Finding the correct Biomass feedstock that will readily grow in Sierra Leone and produce the highest energy content per acre of cultivated land.
  • Finding the right technology to process or convert the Biomass feedstock into the highest yield biogas or syngas.
  • Finding a workable solution to match the extreme weather patterns of Sierra Leone.

USP&E Global determined viable solutions to the above challenges by sourcing and investigating over twenty different types of Biomass agricultural energy crops such as Giant King Grass, Elephant Grass, Sugar Cane, miscanthus, switchgrass, hemp, corn, poplar, willow, sorghum, sugarcane, bamboo,eucalyptus, oil palm and others that could be grown in Sierra Leone Africa. USP&E Global consulted with Biomass conversion technology specialists worldwide, and also spent over a month on the ground in Sierra Leone looking at suitable land and interviewing other local Sierra Leone companies that are either in the process of developing or have developed Biomass projects.

One of the companies interviewed by Glen Cox, Director of Engineering & Projects at USP&E Global and Jim Wessner, Project Manager at USP&E Global was Addax Bioenergy. Addax Bioenergy is a division of the Swiss-based energy corporation Addax & Oryx Group (AOG) who was at the time well into the process of developing a Greenfield integrated agricultural and renewable energy project in Sierra Leone to produce fuel ethanol and electricity. The project’s intent was to produce about 90,000m3 of ethanol per annum, primarily for export to the European Union (EU) market and 15MW of power to be fed into the national grid. Addax Bioenergy staff were very helpful in communicating the challenges of growing and harvesting Biomass energy crops in Sierra Leone.

Based on the above mentioned challenges the results of the Biomass Bankable Feasibility Study are summarized as follows:

  • The best feedstock for producing the highest energy crop yield per acre was found to be Giant King Grass. Giant King Grass is a derivative of the locally grown Elephant Grass and was not considered to be a threat to local indigenous flora.
  • The two suitable technologies found were Anaerobic Digestion and Gasification which produce Biogas and Syngas respectively. The preference was to use Anaerobic Digestion as a means of converting the Giant King Grass to an energy that could be used to power a Gas Turbine or Reciprocating Engine for driving an Electrical Generator. The reason for this was that Biogas has a higher energy content per cubic foot than Syngas.
  • The challenge in Sierra Leone is that the country gets high levels of rainfall in the rainy months making it difficult to harvest the energy crops and during the non-rainy months the agricultural crops required irrigation from the nearby river. These challenges were overcome by staging the planting, growing and harvesting of the energy crops to best match the rainfall patterns.

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