Environmental Engineering Reference
In-Depth Information
growing poplars have been known for many years. They include: land prices, planting stock, fuel,
labor, site preparation, maintenance, fertilizer, irrigation, harvesting, drying, handling, trans-
portation, taxes, and insurance as well as market values at harvest (Lothner 1983; Yemshanov
and McKenney 2008). These variables have not changed over the years, but the absolute costs
and revenues have changed markedly (Isebrands 2007). Economic variables also vary with the
technology used to produce fuels and chemicals from biomass. There are many conversion tech-
nologies possible for use with woody biomass- new and old. They include pyrolysis, gasificaton,
liquefaction, ethanol production by hydrolysis, and other biochemical processes (Phelps 1983).
Unfortunately, although all are technically feasible, none are presently economical on a commer-
cial basis without subsidy (Christersson 2008). Recent developments suggest cellulosic ethanol
will become economic (Decker 2009).
A major limitation can be the availability of markets and proximity to markets (Hoffman and
Wieh 2005). For example, without a viable market, nurserymen are reluctant to risk investment in
scaling up genetically improved clones, and without large numbers of improved plant materials,
large biomass plantations are not possible (i.e., “the chicken and egg” effect). With such uncertainty,
financial credit is often difficult to secure. These factors affect the mindset or psychology of farmers
who might change from traditional crops to biomass crops (van Rees 2008).
When it comes to cellulosic ethanol from biomass, there are a number of hurdles to commercial-
izing the process (Alexander and Gordon 2009). One is difficulty in raising capital for a project
without a cash flow. Another hurdle is the need to convince farmers that a market for their product
will emerge. Moreover, there is uncertainty about the production and transportation costs of a new
crop and product. In addition, the land availability for cellulosic ethanol biomass may be distant
from the access to populated areas where the ethanol is needed, thereby increasing costs. Finally,
there is a political hurdle that is termed the: “blend wall”, i.e., the percent of ethanol blend allowed
in gasoline. Unless the blend percentages are increased, this factor could be a major hurdle. All of
these factors are inherent in the development of a new crop with new conversion technology (Sims
et al. 2009). Dallenmand et al. (2008) summarized the challenges faced with implementing biomass
energy in the EU. These challenges include (1) supply industry with raw material year-round, (2)
ensure a harvest window, (3) ensure harvest and collection efficiency, (4) improve energy processing
technologies, (5) develop reliable storage and transport systems, (6) optimize feedstock quality, (7)
optimize biomass pellet technology, and (8) develop efficient logistical structure such as fuel depots.
All of the limitations and challenges are a part of the development of any new crop and conversion
te ch nolog y.
15.4.5 f
uturE
c
onSidErationS
and
c
oncluSionS
Despite the numerous limitations and challenges to commercializing poplar bioenergy, there are
a number of promising developments and opportunities for poplar biomass ahead. For example,
there are some important policy developments that will affect biomass for energy. At the 17
th
European Biomass Conference in Germany in July, 2009, high officials from the German Ministry
of the Environment and the U.S. Department of Energy spoke about their country's commitment
to biomass as an alternative energy source. Moreover, the United States is now participating in
International Climate Change talks. This development should help short rotation woody crops reach
their potential for part of a carbon management framework (Tuskan and Walsh 2001). Zabek and
Prescott (2005) have shown that the carbon content of poplar biomass plantations ranges from 74
to 89 Mg/ha in 14 years. Moreover, in China, which has the largest number of poplar plantations
in the world, Fang et al. (2006) has shown that the carbon sequestration potential in China alone is
3.8 × 10
7
mt/ha per year.
As the CO
2
concentration in the world increases, there are some potential opportunities for pop-
lar culture. Liberloo et al. (2006) working at the EUROFACE site has shown that poplars are grow-
ing much faster in a CO
2
rich environment.
So, it is hoped that landowners worldwide someday will
