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Biomass handling and logistics – from the perspective of marine terminals

2018-08-30

吳宓蓉 博士

散雜貨碼頭設計顧問專家兼專案經理


Sustainability is the key issue currently in the energy sector. To ensure mankind’s future, it is necessary to make use of renewable energy rather than continuing to rely on fossil fuels. There are various types of renewable energy options, such as solar energy and wind energy. However, only biomass can be used for a wide range of applications, for example wood pellets and wood chips (see Figure 1) can be used in co-firing power plants to produce heat and electricity while biodiesel is used in the transport sector.  

Figure 1 Solid biomass fuels (from upper-left hand with counter-clockwise rotation: wood pellets 6mm, torrefied pellets 6mm, wood chips 0-40mm).

Biomass comes in various forms (e.g. wood pellets, biodiesel, biogas) and increasingly it is being traded in international markets. Bradley et al. [1] have indicated that shipping is the main method to transport biomass. In addition, other studies ( [2] [3]) have concluded that the most preferable biomass supply chain is long distance transport via shipping (see Figure 2). This implies that marine terminals in ports will be the important hubs within the logistics chain.

Figure 2  Geographical system outline [2].

Depending on the commodity form, biomass is handled mostly by dry bulk and liquid bulk terminals. From a marine terminal’s point of view, it is essential to understand the material properties in order to handle biomass properly. For a liquid terminal the challenge is easier to tackle as there are many international standards/specifications that regulate liquid biomass products. No major obstacles are to be expected for handling liquid biomass substances.

However, it is a different story for solid biomass fuels. Compared to other commonly handled dry bulk commodities (e.g. coal, soybean), solid biomass fuels have a much wider range of material characteristics. Table 1 shows the comparison of physical properties, relevant for equipment design and handling system selection, between solid biomass fuels, coal, and grain. It shows that up to four times the volume of solid biomass fuels is required for the same energy output compared to coal (see Table 1).

Table 1 Comparison of physical properties relevant for equipment design and handling system selection [4].

Material property

Solid biomass fuels

Coal

Grain

Bulk density (kg/m3)

220 – 650

640 – 920

700 – 870

Moisture content (%)

4 – 49*

15 – 65

5 – 20

Lower heating value (GJ/ton)

8 – 21

30

N/A

Angle of repose (°)

34 – 47

27 – 38

25 – 27

Wall friction angle (°)

(Stainless steel)

17 – 30

25 – 35

12 – 14

Effective angle of internal friction (°)

40 – 53

55

29 – 31

In addition to the wide range of material properties, the following aspects are important when it comes to solid biomass fuels from the perspective of a dry terminal:

  • Because of the hydrophilic nature of solid biomass fuels, they are sensitive to material degradation. It is recommended to handle and store solid biomass fuels with enclosed or covered equipment/option (e.g. warehouses, covered trough belt conveyors).
  • Solid biomass fuels have a strong tendency for self-heating because of bio-activities and potential high moisture content. Thus, certain common prevention measures performed for coal handling (e.g. compaction) increase the risk of self-heating.
  • Equipment designed for coal handling is suitable for the operation of solid biomass fuels. However, the handling processes/methods need to be adjusted according to the material properties.
  • Because of the low bulk density, more equipment (capacity) is required for the same tonnage handling performance. For solid biomass handling, the volumetric performance should be the main benchmark rather than tonnage performance.

Biomass is a versatile renewable energy option that has many application possibilities. There are two main categories for biomass: liquid biomass substances or solid biomass fuels. No major obstacles are expected for handling liquid biomass substances while the handling of solid biomass fuels requires various adjustments compared to commonly handled dry bulk commodities such as coal and grain. From the perspective of a marine terminal, the handling of solid biomass fuels requires in-depth investigations as the logistics and material characteristics show significant differences.

 

References

1.D. Bradley, F. Diesenreiter, M. Wild and E. Tromborg, "World Biofuel Maritime Shipping Study for IEA Task 40," 2009.

2.R. Suurs, Long distance bioenergy logistics An assessment of costs and energy consumption for various biomass energy transport chains, Copernicus Institute, Utrecht University. ISBN 90-73958-83-0, January 2002.

3.C. N. Hamelinck, Outlook for advanced biofeuls -- International bioenergy transport costs and energy balance, Department of Science, Technology and Society, Utrecht University. ISBN 90-393-3691-1, 2004.

4. M. Wu, "Transitions to biomass handling - A simulaiton approach," in BULK TERMINALS 2017: ACHIEVING EFFICIENCY AND COMPLIANCE, London, 2017.

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