By Kenneth Norris, Contributing Editor, Pulp & Paper International
NEW YORK,
Sept. 13, 2011
(RISI) -
Biomass from cellulosic bioenergy crops could play a much larger role in future energy systems than previously thought. A new study, "The Economic Potential of Bioenergy for Climate Change Migration with Special Attention Given to Implications for the Land System," by Alexander Popp, et. al., concludes biomass could contribute up to 25% of the worldwide energy needs by 2100.
Looking at the long-term economic potential for bioenergy, the study states that the amount of energy produced from biomass would depend on how much stress is placed on the available land and water resources. Some of this stress could possibly increase climate effects.
The more realistic result, according to the researchers with the Potsdam Institute for Climate Impact Research, is to expect biomass to contribute approximately 20% of the expected global energy demand in conjunction with forest conservation and improved technology for agricultural yields. Adjusting the way land is currently used for crops and livestock would help limit the possible effects of climate change.
Using specialized grassy and woody bioenergy crops, Popp says the world can produce enough biomass to contribute up to 100 Exajoules (Ej) by 2055 and 300 Ej by 2095. If forest conservation efforts are included with this production, energy production from biomass is slightly reduced to 70 Ej by 2055 and 270 Ej by 2095.
In comparison, total worldwide energy consumption in 2008 was 475 Ej, a figure that is expected to increase to 780 Ej by 2035, according to the International Energy Outlook 2010 report by the US Energy Information Administration, a division of the US Department of Energy. By 2100, estimates put global energy consumption as high as 1,000 Ej. (One exajoule is approximately 95 quadrillion or 95,000,000,000,000 British Thermal Units, BTUs.)
"Protecting natural forests decreases biomass availability for energy production in the medium, but not long run," says the study. Integrated policies for energy, land use and water management will be required because "our trade-off analysis indicates that forest protection combined with large-scale cultivation of dedicated bioenergy is likely to affect bioenergy potentials, but also to increase global food prices and increase water scarcity."
The study also says that improving carbon capture and storage (CCS) technology used in combination with bioenergy production could result in ‘negative emissions' of greenhouse gases, which would mean actually removing carbon dioxide from the atmosphere. Better CCS technology may also help mitigate the emissions generated by cutting down forests concluded the researchers. But the study does not address other specific environmental concerns, such as the climate effects of replacing virgin forests with forest plantations.
Playing catch-up
Popp's study uses an integrated modeling framework that takes the economic considerations of the land and energy sector into account. As energy production theoretically moves to a low-carbon transition, the amount of bioenergy available is calculated based on possible climate change scenarios. In the modeling framework, bioenergy competes directly with other currently existing energy options on the basis of costs.
The difference between the two main scenarios is whether forest conservation is taken into account which considering available biomass for bioenergy production. In the demand scenario without forest conservation, "biomass from dedicated bioenergy crops will contribute 25% to the total global demand for energy carriers," says the study and, "95% of the bioenergy production will be converted into secondary energy in combination with carbon capture and storage (CCS)." The second demand scenario, where forests are excluded for conservation and to mitigate the effects of climate change, "affects the availability of cost-efficient biomass for energy production significantly."
The use of carbon capture and storage technology plays heavily in the study's findings, depending on infrastructure developments and new storage capacities to help achieve the bioenergy levels in the forest conservation scenario. In the long term, "the use of biomass in the energy system is competitive, mainly due to the option of generating negative emissions in the energy system by using CCS," says the study.
Other factors could also affect the proportion of biomass available for bioenergy. The study states that its assumption of the global availability of cellulosic biomass is taken without any trade restrictions, which could overestimate bioenergy potentials. As the biomass trade, such as wood pellets, ethanol and palm oil, increase to meet a growing demand, the volume of biomass for bioenergy would be affected. Competing application of biomass for soil improvement and animal feed could also reduce the numbers.
However, Popp states that the overall results of the study are "in the lower range of recent studies of bioenergy potentials." The wide differences between the studies often vary on land availability for biomass plantations, and current and future yields in crop production. By using a trade-off between land expansion and improved technology leading to higher yields, this study is able to take into account population growth, demands for food and water, as well as anticipated improvements in technology.
The study concludes that bioenergy from lingo-cellulosic energy crops can be a cost-efficient contribution to the energy mix of the future. Without any protections for the world's forests, the potential for biomass as an energy resource could be "a considerable amount of the world's primary energy demand up to 2095." However, by protecting untouched tropical forests and other high-carbon ecosystems, biomass' bioenergy potential may be diminished in the medium term, but could gain as time and technology catch up.
