Page 3 - Module_5

This is a SEO version of Module_5. Click here to view full version

« Previous Page Table of Contents Next Page »
3
FAO/UNEP/UN-Energy Bioenergy Decision Support Tool -
MODULE 5: Land Resources
LAND USE INTENSITY FOR ENERGY PRODUCTION
The LUI of energy systems essentially provides some frst-order
indication of the types of land use pressures associated with
the transition to sustainable energy systems; the LUIs of energy
systems can vary by several orders of magnitude, especially for
renewable energy. Nuclear and fossil fuels have low land use
intensities, while renewable energy systems exhibit considerable
variation, ranging from modest requirements for geothermal and
solar PV to extremely high requirements for bioenergy systems.
An example of land use intensities with respect to electric power
production in the U.S. is given in Table 1. The systems with the
lowest LUI are nuclear, coal and geothermal, although geothermal
also has underground impacts that other sources do not have.
Solar and wind have LUIs that are 1-2 orders of magnitude
higher while biomass has LUIs that are 2-3 orders of magnitude
higher. However, since biomass energy systems normally have
co-products and since the land can often accommodate other
uses, the effect of the land impacts can be signifcantly less. For
some sources such as wind and solar, the overwhelming majority
of land impacts are due not to the land occupied, but rather to the
fragmentation and the effects on birdlife (McDonald et al 2009).
It is also important to note the considerable difference in the
quality and timeframe of land impacts due to energy consumption
and not just quantity as measured by LUI. In some cases, land
resource impacts are not easily reversed; in the case of coal,
hundreds of years may be needed for recovery or reclamation
from the toxic effects of coal mining. In the case of nuclear power,
the consequences on the affected land of a serious accident
might require tens of thousands of years for recovery. Conversely,
land use changes associated with renewable energy systems
are generally not toxic and may be reversible. Land resource
impacts due to bioenergy are qualitatively different from those
of other energy systems; land used for bioenergy can in some
circumstances be converted back to its previous use or to some
other use, especially if the previous uses were agricultural. There
may nevertheless be serious—and in some cases irreversible—
impacts, when high biodiversity land (High Biodiversity Environ-
ments) or land with high carbon content is used for bioenergy
production (High Carbon Content Environments).
AVAILABILITY OF LAND FOR BIOENERGY
PRODUCTION
Agricultural reform, climate change and energy security have
been central drivers in renewed enthusiasm for liquid biofuels for
transport, which have also been seen as providing new opportuni-
ties for economic revitalisation in rural areas, in developing and
developed countries alike. At the same time, growing demand is
raising concerns about greater amounts of land being devoted
to bioenergy production, which might displace food production
and lead to undesirable environmental impacts such as loss of
biodiversity or degradation of ecosystem services.
It is diffcult to estimate the global quantity of land devoted to
bioenergy production due to the co-products involved and the
rapid changes in bioenergy markets. Under current trends,
the land requirements for liquid biofuels could reach 35 to 166
million hectares by 2020, according to some estimates (UNEP,
2009). A far greater amount of land is required to support the
use of woodfuels for traditional bioenergy uses: the total biomass
for traditional uses currently amounts to more than 80% of all
biomass used for energy globally (IEA, 2009). However, determin-
ing how much of that traditional biomass use is sustainable (i.e.
has not surpassed the sustainable yield of the relevant forest area)
can generally only be estimated for a specifc region (FAO, 2010b).
The distribution of land globally is rather uneven with respect to
population. Figure 1 shows per capita land by type for various
regions and countries. Some developing regions, such as
sub-Saharan Africa and Brazil, are well above the world average;
by contrast, many regions in Asia are below the world average.
On average, one expects that there will be more land pressures
and more constrained options for liquid biofuels for transport
in many regions of Asia. Even in some parts of Asia, however,
there are less populated and highly productive regions that have
signifcant potential. Yet in terms of the major world regions
and bioenergy trade, it seems likely that only Latin America and
sub-Saharan Africa could become major exporters.
Table 1: Land use intensity for various electric power production systems
Type
Reference
capacity
Land use intensity
for Installed Power
(km2/GW)
Land use intensity for
Electricity Generation
(km2/TWh/yr)
Assumptions and/or Type of impact
low
high
low
high
Coal
85%
18,6
126,6 2,5
17
Area disturbed by mining
Hydropower 44%
62,2
354,8 16,1
92,1
Area submerged by lake
Biomass
Electricity 75%
2844
4294 432,9
653,6
Area for growing woody feedstock (willow)
Geothermal 85%
7,5
103,6 1,0
13,9
Area covered by plant and access infrastructure,
fragmented habitat
Solar
Thermal 29%
25,9
51,8 10,2
20,4
Area covered by plant and access infrastructure,
fragmented habitat
Solar
Photovoltaic
(PV)
28%
51,8
129,5 21,1
52,8
Area covered by plant and access infrastructure,
fragmented habitat
Onshore
Wind
35%
199,4
242,8 65,0
79,2
Area covered by turbine and access infrastructure,
fragmented habitat
Nuclear
91%
3,02
4,78 1.9
2.8
Area covered by plant, as well as area for uranium
mining and waste storage
Source: Adapted from McDonald et al (2009)