CENBIO - Enabling sustainable and cost-efficient bioenergy in Norway

Among the highlights from SP4 in 2015, the following one from WP4.2 should be mentioned:
Effects of stem-only and whole-tree harvesting on ground vegetation plant species diversity and their cover were investigated as outlined in the below section for WP4.2. An overall loss of ground vegetation biodiversity was induced by harvesting and there was a shift in cover of dominant species, with negative effects for bryophytes and dwarf shrubs and an increase of graminoid cover. Differences between the two harvesting methods at both sites were mainly due to the residue piles and the physical damage made during the harvesting of residues in these piles.

WP4.1 - Extended life cycle assessment 

During 2015, research activities mainly focused on improving the life-cycle assessment approach to embed the complex temporal and spatial dynamics of the climate impacts from bioenergy systems. The work specifically addressed the changes in biogeochemical (i.e., related to carbon) and biogeophysical (i.e., related to albedo) effects.

Climate impact perturbations from forest bioenergy are temporary, as opposite to warming from fossil carbon that causes a sustained and irreversible temperature increase. Further, cooling contributions from changes in surface albedo can offset the temporary warming from bioenergy and cause a nearly neutral climate change impact. With recent research we associated the impacts from CO₂ emissions from bioenergy to those of short-lived Green House Gases (GHGs). Further efforts also focused on the acquisition of empirical data via satellite retrievals and national forest inventories to derive spatially explicit indicators that can better represent the spatial variability of the impacts.

Participation to prestigious international events and collaborations with leading institutions at an international level were at the core of the activities. The work achieved in CenBio was presented at the UNFCCC conference in Paris "Our Common Future Under Climate Change" (7-10 July). This conference is the scientific events preceding the negotiations of COP21 held in December that provided the scientific basis for the discussion. NTNU is also chairing the global warming task force of the UNEP-SETAC life-cycle initiative and is a member of IEA Bioenergy Task 38.

WP4.2 – Ecosystem Management

Intensified use of the forests as a feedstock source for bioenergy has to meet the requirement for ecological, social and economic sustainability. WP4.2 deals with short- and long-term ecological sustainability, largely at site scale. Figure 1 shows changes in ground vegetation with time at a harvesting site. Forest biomass harvesting cannot be considered sustainable if it leads to a loss of biodiversity. We therefore need to understand how biodiversity is affected by intensified forest harvesting, including harvesting of branches and tops.

Figure 1: Changes in ground vegetation with time at Gaupen, Hedmark. Harvesting took place in March 2009 and removal of residue piles in September 2009. (Photos: Ingvald Røsberg.)

Effects of stem-only and whole-tree harvesting on ground vegetation plant species diversity and their cover were investigated at two Norway spruce sites in southern Norway, a steeper and wetter site in western Norway and a less steep and drier site in eastern Norway. In the whole-tree treatment, residue piles were left on-site for six-eight months before removal. We compared the number of plant species in different groups and their cover sums before and shortly after harvesting, and between the different treatments, using non-parametric statistical tests.

An overall loss of ground vegetation biodiversity was induced by harvesting and there was a shift in cover of dominant species, with negative effects for bryophytes and dwarf shrubs and an increase of graminoid cover. Differences between the two harvesting methods at both sites were mainly due to the residue piles and the physical damage made during the harvesting of residues in these piles. The presence of the residue piles had a clear negative impact on both species numbers and cover. Pile residue harvesting on unfrozen and snow-free soil caused more damage to the forest floor in the steep terrain at the western site compared to the eastern site. Although short-term effects on biodiversity were negative, it remains to be seen whether there will be any long-term effect. To this end, studies of changes with time in the ground vegetation at these sites are continuing.

 WP4.3 – Cost Assessment and Market Analysis

In the report "Best scenarios for the forest and energy sectors – implications for the biomass market", the future demand and supply of biomass for bioenergy were assessed in three alternative scenarios, which were specified by different assumptions on economic, technological, climatic and regulatory aspects. Two large scale techno-economic regional global models were soft-linked to each other and used to quantify the impacts of the scenario assumptions: the TIMES-VTT model of global energy systems and the EFI-GTM model of the global forest sector (i.e. forestry, forest industries and wood-based energy). Focus of the scenarios was the period up to 2030, but less comprehensive indicative results were provided up to 2050 as well. While all types of biomass were analysed, developments concerning forest biomass were discussed in more detail.

What all three scenarios have in common is that the use of biomass for energy is projected to increase considerably in the future. The main driver for this development is the decreased competitiveness of fossil fuels either due to their high prices as such or due to their high use costs caused by tightening climate policies. In particular, there is a need to take in use quickly applicable solutions for shifting the transport sector from using fossil fuels to renewable energy. In the regions where the use of solar and wind power were assumed to become increasingly important for power supply, biomass provides options for power system reserves and regulating power. In the long run, the analyses show that bioenergy may provide possibilities even to achieve negative emissions through bio-CCS –technologies (BECCS). Such option appeared important because in some sectors, like in agriculture, emissions can be hard to cut down.

At the global and European level, majority of the energy biomass was projected to come from the agricultural sector. Despite that, the amount of forest chips and roundwood used to produce heat, power and liquid biofuels increased drastically. In order to satisfy this demand for energy wood in a sustainable manner, the analysis show that it is essential that planted area of fast growing forests increases much and that a shift from household fuelwood burning to modern energy technologies takes place to a large extent.

At present, most of the global bioenergy is consumed in traditional small scale uses. In the future, the analysis shows that this picture is expected to change radically. According to the energy systems analysis documented in the report, the total bioenergy use could double to over 100 EJ during 2010– 2030. About one third of that amount could be utilised for power and heat production in the energy sector and industry.

When going beyond 2030, the analysis indicates that global bioenergy demand could again nearly double between 2030 and 2050, reaching up to 180 EJ in the two scenarios where the warming of climate is limited to 2 °C through global efforts. Then about 90% of the estimated sustainable global biomass potential would be taken into use, and more than half of the total increase would be used for producing liquid biofuels, mainly for the transport sector. The largest contribution to the increase in bioenergy use would come from energy crops, most clearly when moving beyond 2030. Even though modern energy wood does not play a major role in the total energy biomass palette, its use increases so much that it is essential to have additional supply sources for wood. The development calls for increases in the forest plantation area and large-scale shift from traditional fuelwood use to modern bioenergy.

Sustainable bioenergy can be one of the cornerstones of renewable energy supply when moving to a low carbon society. Nonetheless, the analysis clearly shows that due to the limits on sustainable bioenergy production, a wider portfolio of renewable energy sources and technologies will be necessary for reaching the policy targets to tackle the climate change. Furthermore, considering the high demand for energy biomass projected in the scenarios, it is essential that technical improvements and innovations take place in all areas to relieve the pressure on the resources, let it be energy production and storage, use of energy, or use and reuse of biomass, materials and land.

Numerous uncertainties prevail behind the scenario projections. As mentioned above, the sustainability criteria of biomass will need to be developed further, and once that happened, the new criteria may affect the question to which extent different biomass grades will be considered to be carbon neutral and thus applicable to reduce greenhouse gas emissions in the future. If the palette of biomass sources usable for achieving emission reduction targets is narrowed, the use of other, more costly, carbon neutral energy forms would need to be increased. Future LULUCF (i.e. land use, land use change and forestry) policies are partly tied to that issue. For instance, if changes in carbon stored in forest land would be fully accounted as a part of the annual CO₂ emissions of the countries that might bring changes to forest policies and decrease both the roundwood supply and wood use in the countries affected.

Regarding agro-biomass, the question of the population development, development of the dietary habits and technological change in agriculture are decisive in determining the availability of land for energy biomass supply. Another important and uncertain issue is the impact of climate change on the future harvest levels.

Political choices both in individual countries and internationally are of great importance in shaping the future global use of energy. In two of the scenarios analysed, it was assumed that the climatic warming is limited to 2 oC. This calls for strong commitment of the countries toward achieving this goal to be taken soon. If this will not happen, as it was assumed in the third scenario, less biomass will be used for energy globally. Still, the decisions already made in the EU create raising markets for bioenergy technology.

In the forest sector, the analyses show that the demand for wood pulps is increasing particularly in the production of traditional and new packaging materials, household and sanitary papers, textiles, fluff pulp and novel fibre uses. This development more than offsets the declined demand for wood in production of printing and writing papers, the demand for which is projected to decline globally. The same kind of wood raw material is also used in the production of boards, like OSB and particle boards. While there is some competition over wood fibre between the forest industries and the energy sector, the production of the former is not much affected. Yet, the pulpwood prices increase some due to increased competition. The production and consumption of solid wood products, sawn wood and plywood increase considerably as well, and this eases the supply of sawmill chips and logging residues. Overall, the model analyses show that the most important increases in the forest industry production will take place outside the EU, because the markets are already relatively mature in Europe.