Solid biomass from forests, farms and cities provides a major energy source for heat and power generation, potentially accounting for a ﬁfth of global energy consumption by 2050 amid accelerated adoption of renewables. But wood and crop residues need to be collected from widely dispersed sites and stored for use at the optimal time, and at a cost-effective scale, in district-heating systems, power plants, and combined heat and power plants. This technology brief from the International Renewable Energy Agency (IRENA) examines the multi-dimensional logistical challenges of establishing a steady supply chain for solid biomass.
This multi-dimensional logistical challenge is successfully met in many places around the globe. Wood pellets for power plants are shipped from Southeast Asia to Japan and from Southwestern Europe to the Netherlands, taking advantage of their high energy density, low moisture content and durability, as well as the low cost of sea transport per tonne-kilometre of cargo. Wood chips and pellets also fuel district heating plants in towns and cities of other European countries, such as Lithuania and Ukraine. Straw and other agricultural residues from production of food crops are being collected to provide heat and power in some villages in India. In all these places, an effctive supply chain has been established, with contracts to ensure provision of suffient feedstock at the required quality and cost.
But large quantities of available residues are not being collected. In Sweden and other countries with large managed forests, just a small share of the tree tops and branches left over from logging operations are collected. In Canada, large amounts of dead wood are abandoned in forests after being felled by storms or left standing in forests after insect infestations. On many farms around the world, crop residues not needed to feed or bed livestock are left in the fild or burned to make room for the next planting. Typically, such residues are discarded because the cost of collecting and transporting them is greater than the market value they can fetch. Their enhanced use will therefore require more cost-effctive logistical approaches or highervalue-added applications.
Quality standards play a key role in expanding solid biomass markets. Diffrent feedstocks have diffrent physical and chemical characteristics that vary by region and season of the year. Often they start with too low an energy density for practical use or too high a moisture content for practical transport and storage. Standardisation of biomass feedstocks, to ensure quality at point of use, is therefore an important enabler of solid biomass trade in an increasingly globalised market. Feedstock pretreatment, with drying and densifiation, can help ensure quality standards are met.
Sustainability standards for solid biomass fuels are also likely to play a growing role. The wood pellet trade has generated interest in ensuring that pellets are sourced from the residues of lumber production that displace carbon emissions from fossil fuels without affcting land use, or from short-rotation wood crops that quickly compensate for combustion with carbon uptake. When wood residues are used, enough should be left in the forest to sustain biodiversity. When crop residues are used, enough should be left on the ground to maintain soil carbon and quality.
The wood pellet industry has made considerable progress in developing the logistics infrastructure for global biomass supply, including well-defied supply chains, contract provisions, quality standards and terms of trade. As concerns continue to mount over environmental degradation and climate change, sustainability standards are being developed and adopted to meet these concerns. However, considerable further logistical effrts will be required to harness the full increment of sustainable solid biomass supply for productive application in the heat and power sectors.
This technology brief focuses on the commercial supply of solid lignocellulosic biomass for heat and power. The range of solid biomass sources and applications is wide, but several are prevalent:
- use of biomass residues for cooking and heating;
- use of biomass residues in industrial applications for heat and power;
- use of biomass pellets and fiewood in household heating;
- use of biomass chips and pellets in industrial/standalone heat and power applications.