Emissions Scenarios - IPCC

136 Scenario Driving Forces
Table 3-6: Global renewable energy potentials for 2020 to 2025, maximum technical potentials, and annual flows, in EJ. Data
sources: Watson et al.. 1996; Enquete-Kommission, 1990?
Consumption Potentials by Long-term Technical Annual
1860-1990 1990 2020-2025 Potentials Flows
Hydro 560 21 35-55 >130 >400
Geothermal - 20 >800
Wind - - 7-10 >130 >200,000
Ocean - - 2 >20 >300
Solar - - 16-22 >2,600 >3,000,000
Biomass 1,150 55 72-137 > 1,300 >3,000
Total 1,710 76 130-230 >4,200 >3,000,000
(Nakicenovic etal., 1996) and shown in Table 3-6. A summary
of the literature of renewable resource development potentials
consistent with IPCC WGII SAR, including a detailed regional
breakdown, is given in Christiansson (1995) and Neij (1997).
Hydropower cun'ently provides some of the cheapest electricity
available in the world, although the potential for new capacity
is limited in some regions. WEC (1994, 1995a) estimates the
gross world potential for hydroelectric schemes at about 144 EJ
per year, of which about 47 EJ per year is technically feasible
for development, about 32 EJ per year is economically feasible
at present, and about 8 EJ per year is currently in operation.
IPCC WGII SAR (Nakicenovic etal, 1996) gives a comparable
medium-teiTn potential of between 13 and 55 EJ, and a
maximum technical potential above 130 EJ.
Other important renewable energy resources are wind and
solar, as well as modem forms of biomass use. Biomass
resources are potentially the largest renewable global energy
source, with an annual primary production of 220 billion oven
dry tons (ODT) or 4500 EJ (Hall and Rosillo-Calle, 1998).
The annual bioenergy potential is estimated to be in the order
of 2900 EJ, of which 270 EJ could currently be considered
available on a sustainable basis (Hall and Rosillo-Calle, 1998).
Hall and Rao (1994) conclude that the biomass challenge is
not one of availability but of the sustainable management,
conversion, and delivery to the market place in the form of
modem and affordable energy services. It is also important to
distinguish between harvesting and deforestation; the fonner
results in afforestation, and the latter in conversion of forest
land for other uses, such as agriculture or urban development.
The use of biomass as an energy source necessitates the use of
land. Based on estimates by IIASA-WEC (1995), by 2100
about 690-1350 million hectares of additional land would be
needed to support future biomass energy requirements for a
high-growth scenario. However, the additional land
requirement for agriculture is estimated to reach 1700 million
hectares during the same period. These land requirements can
^ All estimates, excluding biomass, have been converted into thermal
equivalents with an average factor of 38.5%.
be fulfilled if the potential additiofial arable land is taken into
account (at present this is mostly covered by forest). Hence,
land-use conflicts could arise, and particularly for Asia which
is projected to require its entire potential of arable land by
2100. Africa and Latin America may have sufficient land to
support an expanded biomass program. One estimate (WEC,
1994) shows that Africa can support the production of biomass
energy equivalent to 115% of its current energy consumption
(8.6 EJ).
Some authors stress that increased demand for bioenergy could
compete with food production (Azar and Bemdes, 1999). They
note that the competitiveness between food and bioenergy
production is not realistic in most energy-economy models;
rather it is treated in an ad hoc fashion with the assumption that
enough land is secured for food production. In reality an
increasing competitiveness of bioenergy plantations may cause
food prices to jump. Some developing regions, in particular
Africa, are often assumed in scenarios to become major
importers of food (Azar and Bemdes, 1999).
Unlike hydropower, most of the technologies that could
harness these renewable energy fonns are in their infancy and
are generally still high cost (although wind power is becoming
increasingly competitive in some areas). Conversely, the
potential for improvement in technical performance and costs
is substantial. Thus, the future resource potential of these
renewables is lai'gely determined by advances in technologies
and economics (discussed in Section 3.4.4).
Advances in renewable energy technologies could materialize
to a significant extent even in the absence of climate policies,
albeit conventional wisdom holds that such policies could
accelerate their dilfusion considerably. According to IPCC
WGII SAR (Nakicenovic et al, 1996), in the medium-term (to
2025) the largest renewable energy potentials lie in the
development of modem biomass (70 to 140 EJ), solar (16 to 22
EJ), and wind energy (7 to 10 EJ) as indicated in Table 3-6. In
the long term the maximum technical energy supply potential
for renewable energy is evidently solar (>2,600 EJ), followed
by biomass (>1,300EJ).