One basic difference between bioenergy and other renewable forms of energy (hydro, wind, solar) is that in the first case, the primary resource must be produced and/or collected, with its corresponding cost, while for the other systems, the “fuel” (water, wind, solar radiation) is available for free.

Most of the wood for bioenergy currently comes from industrial wood residues (such as waste liquors from pulping industry and bark, sawdust and other wood wastes from sawmills and pulp and paper mills). However, on the long run, when all the resource is exploited, solid biofuels will have to be based on the recovery of the forest residues as well as on dedicated agricultural production.

The harvest potential for forestry products and residues depends on the mechanisation level. And the mechanisation largely depends on the terrain, where steep terrain will limit the use of heavy or large forestry equipment. In Austria, the forest owners are responsible for building access roads which are absolutely essential for the procurement process. The following figures for harvest potential with the differing levels of mechanisation are based on the Austrian experience:

Harvesting Capacity Type of Harvesting Equipment Involved Cost of Harvesting
3-40 m³/day  Manual cutting  Chainsaw, extraction by hand  36-50 €/ solid m³
30-97 m³/day  Partially mechanised  Chainsaw, extraction by tractor, winch or skidder  16 – 35 €/ solid m³
60 – 129 m³/day  Highly mechanised  processing using a processor, extraction by cables  21 – 36 €/ solid m³
59 – 120 m³/day  Fully Mechanised  processing by harvester, extraction by forwarder  17 – 25 €/ solid m³

Biomass availability

There are several biomass sources depending on land uses:

Forests:

  • Natural (wood residues, etc..)
  • Managed (Short rotation plantations (Willow, Poplar, wood for paper)

Crop lands:

  • Food dedicated crops: Considerable amounts of residues (straw)
  • Biofuels dedicated crops: Sugarcane, S. Sorghum, Rapeseed, Sunflower,…

Pasture and grass land. Mixed with manure in anaerobic digesters

Food and agricultural organic wastes: Feedstock with great moisture content as manure, sludge, etc..

Water ponds and sea: Microalgae, Seaweed, other water plants (water hyacinth, etc..)

In 2010 the total supply of all woody resources in the EU 27 was about one billion cubic meters (70% from forests and 30% from outside the forest). In oven dry tonnes this is about half a billion oven dry tonnes and equals about 202 Million TOE. The assumed total energy consumption  from forests in the year 2010 adds up to 71,8 MTOE.

This corresponds to about 800 M m³ with a 57% will be used for material purposes and 43% for energy.

In Europe, the straw production is estimated to be approximately 120 million tons, but the straw actually collected in Europe is no more than 50%

Below the estimated global biomass energy potential and land availability  expected from 2020 and 2050:

Year forecast

World potential

2020

2 Billion TOE/y

2030

4,2 Billion TOE/y

2050

10,4 Billion TOE/y

 

Land management

Now (Billion ha)

2050 (Billion ha)

Total Crop Land

1.8

2.65  (9,3 Billion people)

Forest Natural + managed Land

4.8

4,24

Pasture  &  grass land

3,46

3,1

Others (desert, palude…)

3

3

Problems related to Biomass large scale supply

One of the biggest problems related to biomass large scale supply is the energy density. Briefly, if biomass moisture of conventional wood is 30%, this means that every 1 ton of wood transported, 300 kg are water. Additionally, biomass feedstock shape (chipped, pelletized, rounded, baled), strongly influences the bulk density and affect the transportation economics. For this reason, compactation and densification are considered crucial for an efficient biomass supply. The figure below shows the energy density and bulk density of different biobased feedstock.

immagine3

In addition to the bulk and energy density, large scale biomass supply is affected by a wide range of bottlenecks including raw material initial cost, biomass producers involvement, environmental regulation and sustainability. Finding solutions for all these problems means finding the solution for the creation of the future biomass commodity in Europe and worldwide.

 

PROBLEMS

SOLUTION

High quality biomass (wood) is considerable but limited expensive and not always sustainable Utilization of agro forestry residues. High availability and fully environmentally sustainable
Agro-forestry residues have lower quality and higher micro-elements (K, Ca, Mg, ashes) content Blending of different biomass feedstocks to arrange suitable average composition
Availability is mainly reduced to forests areas Residues have much lower costs and dispersed and available almost everywhere
Low energy density and bulk volume (KJ/m3) of fresh biomass affect storage costs and transportation efficiency First step chipping activities, enhance biomass energy density increasing transportation efficiency
Biomass degradability affect large distances transport activities, long time storage Agropellets production, with low moisture and high energy density. Avoiding degradation and transportation issues.