A responsibility for future generations
Globally, the use of raw materials (for the production of food, energy, and construction) has increased exponentially, especially since the nineteenth century. The future prediction shows that demand for food, fuel and construction materials will grow because of the increasing global population and economic growth. Moreover, climate change and resource depletion pose a serious threat to planet including human civilization. Buildings and construction account for more than 35% of global final energy use and nearly 40% of energy-related CO2 emissions.
Resources from forests provide renewable construction materials (especially for buildings), pulp and paper, energy, bioproducts and more. Forests sequestering carbon and wood products storing carbon have the greatest potential to mitigate climate change.
Combining carbon storage and carbon displaced from using forest-based construction materials, especially building construction, is one of the most efficient options to mitigate climate change.
Despite abundant availability of forest resources, it may be hard to fulfill the global demand for forest resources to produce needed construction materials, pulp and paper, energy and fuel without continuing practicing sustainable forest management. Society sees forests now as a source of renewable and sustainable natural resources for building materials, fibers, biofuel, and other renewable materials to mitigate climate change while fulfilling society’s increasing demands for economic well-being.
Optimal and judicious use of scarce resources is critical; therefore, the actual environmental and economic performances of different products and services coming from forest resources have to be considered. Forest-based products provide economic, environmental and societal benefits and these benefits need to be properly quantified using tools that can properly assess and compare the benefits of different products coming from forests.
Life cycle assessment (LCA) is a scientific approach to analyze and quantify the environmental burdens associated with resource extraction, manufacturing, use and disposal of a product.
Manufacturing of forest-based products: from traditional building materials, to emerging building products including nanomaterials.
Forest-based products are derived from what is commonly called roundwood or trees felled in their natural state for industrial purposes. For this article, the term “roundwood” is considered the raw material to produce final products such as those discussed in more detail later, although there are many other products that can be produced. Forest harvesting generates roundwood that feeds both the wood products (i.e., lumber, wood-based panels, bridges, pallets, etc.) and the pulp and paper sectors. The remaining forest residues left after harvesting and the mill residues produced during roundwood processing can be used for fuels such as pellets and firewood and biomaterials such as nanocellulose. A comprehensive review of various categories of wood products can provide a holistic view of the current state of research, especially performances related to environmental impacts.
The life cycle starts in the forests, which are either natural or planted. Natural regeneration occurring in a natural forest with no or little human activity. Unlike natural forests, which are the dominant type globally, planted forests are established through planting or intentional seeding of native or introduced species primarily for wood production. Regardless of forest type, roundwood harvested from forests is transported to the production facility typically by logging trucks and stored on-site in yards until the logs are ready for processing. Wood quality and log size tend to determine the final product type. Industrial roundwood can be broken into several categories such as sawlogs
and veneer logs, polewood, pulpwood, and fuelwood.
Primary wood processing includes the sawing of sawlogs into slabs for lumber production, slicing of veneer logs into thin sheets of wood and converting pulpwood into wood chips or fiber through mechanical (grinding) and chemical means of pulp production. Lumber, once sawn, is typically finished by air- and/or forced-drying for dimensional stability and by planing for smoothness and proper sizing. Lumber can be used as-is for building or processed into other products such as wood flooring and mass timber products for mass timber buildings.
There are various traditional engineered wood products such as oriented strand board (OSB),
medium-density fiberboard (MDF), high-density fiberboard (HDF), particles boards and so forth, can be manufactured from wood particles combined with synthetic resin or natural adhesive. Wood pulp can be further processed into other products such as paper and nonstructural wood-based panels.
Emerging wood products or mass-timber such as cross-laminated timber, glue-laminated timber and so forth, had been developed for the main structure construction of tall-wood buildings or high-rise buildings.
Nanomaterials and nanocellulose comprised of nanosized (1–100 nm) cellulosic fibrils or crystals
are obtained generally from plants. Nanocellulose is considered a novel advanced biomaterial but the global economic impacts of nanocellulose are projected to reach $600 billion by 2020, which is highly unlikely given the current commercial product output. There are different types of nanomaterials produced from cellulose, which is the world’s most abundant polymer. Cellulose makes up about 38% to 49% of dry wood with the remainder being made up of hemicellulose (15–26%) and lignin (18–35%), along with small amounts of extraneous materials.