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FAO/UNEP/UN-Energy Bioenergy Decision Support Tool -
MODULE 5: Land Resources
Module 5: Land Resources
With a growing world population, a changing climate and increas-
ing material demands, land is becoming a scarce resource, with
many different and sometimes competing demands. Global trends
suggest that increasing land pressures will require considerable
care in managing biofuels expansion, in order to prevent loss
of biodiversity, damage to ecosystem services and release of
carbon from sensitive areas (UNEP, 2009). For the assessment of
bioenergy options, the key functions and potential conficts that
need to be addressed in relation to land resources include the
following:
• habitat, housing and various economic sectors;
• food and livestock production;
• serving as carbon sinks to help address climate change;
• host land used for biodiversity which provides preservation;
and
• protection of ecosystem services that can support human
activity.
In this Module, a review is given on the key drivers and analytical
approaches associated with the allocation of land resources for
bioenergy production. An overview of land use for bioenergy
systems is frst provided, followed by a summary of the principles
and assessment methods for determining the appropriate
locations for bioenergy production. The question of where to
produce bioenergy requires consideration of both the suitability
of different land types for energy crops as well as the availability
of land based on current and planned uses. Special emphasis
is given to the assessment of impacts related to biodiversity,
GHG emissions (due to land use change), food security and
the provision of ecosystem services. The possibility of using of
marginal or degraded lands for bioenergy production is also
reviewed briefy; where feasible, some additional value-added
might be obtained when using land that has been abandoned or
has low-vale uses.
Consideration is also needed for the possibility that subsistence
farmers or small landowners might be driven off the land to make
way for bioenergy production; they may move into natural areas
and place additional environmental and resource pressures.
Improving land tenure systems and creating secure rights to land
for productive uses and habitation is needed to reduce such
pressures; such issues are not addressed in this module but are
considered briefy elsewhere in the DST
<Module 6: People and
Processes>.
The importance of land tenure has been noted by
the Convention on Biological Diversity as being especially relevant
for indigenous peoples in the context of biofuels expansion and its
impacts on biodiversity (CBD, 2010).
This module is concerned mainly with dedicated bioenergy
feedstocks that are obtained from agricultural crops or energy
plantations. The removal of wastes and residues can also have
some negative environmental impacts but such impacts are
qualitatively different and would generally be evaluated in a
different manner. When the source of biomass is solely or mainly
from wastes and residues, a simplifed approach could be used
in which the analysis might be focused on the effects of the
diversion of wastes and residues, and the identifcation of any
impacts that need to be addressed.
Land Use Efficiency
The conversion effciency of sunlight into energy stored by
plants is typically 1-3%, and therefore bioenergy—as the stored
form of solar energy—is much more land-intensive than other
energy sources (Fritsche et al, 2010. Signifcant quantities of
land—as well as water and nutrients—may be needed to grow
biomass feedstocks (except for wastes/residues and aquatic
biomass). The associated environmental impacts (both positive
and negative) are therefore generally more signifcant relative to
the energy produced than those of other energy systems. In this
section, some defnitions and metrics are presented for land use
associated with bioenergy systems and some comparisons for
other energy sources in the case of electricity production. It can
nevertheless be diffcult to make direct comparisons between
bioenergy and other energy systems, due to the fact that there
will often be co-products and multiple potential conversion paths
for bioenergy systems, which will generally not be the case for
other energy systems. Land use is a complex topic that is beyond
the scope of this brief exposition; however, in this section, an
overview of key elements related to land use requirements for
bioenergy is provided.
DEFINITIONS AND TERMS
As with any system that requires signifcant quantities of land,
there will be major couplings between the bio-physical properties
and the socio-economic context of bioenergy use. In order to
conduct assessments and provide advice for policymakers, it is
therefore important to defne some key terms. Land cover refers
to “the observed physical and biological cover of the earth’s land,
as vegetation or man-made features.” In contrast, land use is “the
total of arrangements, activities, and inputs that people undertake
in a certain land cover type” (FAO/UNEP, 1999; IPCC, 2000).
Determination of the suitability of land for bioenergy production
is based on the analysis of land cover data along with climatic,
soil and other bio-physical data (see Land Suitability Assessment
below). Assessment on the availability of land considers what
activities are occurring in given areas, and requires a fairly broad
assessment of the existing types of land use and their impacts
and/or value. Land use change refers to transformations in the
category of land use, such as forested land that is converted for
agricultural uses.
The energy or power density is normally expressed in Watts per
unit of land (W/m2) and provides an initial estimate of the energy
or power delivered, based on the quantity of land needed for the
energy system, including cultivation are in the case of bioenergy.
The highest delivery of high-quality (electric) renewable energy
per unit of land is likely to be from solar PV, which could capture
on the order of 10-20% or roughly 10-40 W/m2 for European
conditions when placed on south-facing surfaces (MacKay, 2008).
In tropical and sub-tropical regions, the energy or power density
would be much higher. Wind power would typically have a much
lower power density and bioenergy lower still.
The land use intensity (LUI) is a static measure of the land
needed for continuous operation and that which is unavailable or
otherwise impacted with respect to other uses. The LUI, when
evaluated in a comprehensive manner, can include somewhat
indirect effects such as fragmentation of habitats. The LUI is
therefore more comprehensive as an indicator of environmental
impacts than the energy or power density. Furthermore, the
calculation of power density is somewhat more location-specifc
than LUI because it is based mainly on the energy that can be
instantaneously extracted whereas the LUI includes various
impacts that are then averaged across the power or energy that is
available.