Roskilde
University
A sustainable energy future
Construction of demand and renewable energy supply scenarios
Sørensen, Bent
Published in:
International Journal of Energy Research
DOI:
10.1002/er.1375
Publication date:
2008
Document Version
Early version, also known as pre-print
Citation for published version (APA):
Sørensen, B. (2008). A sustainable energy future: Construction of demand and renewable energy supply
scenarios. International Journal of Energy Research, 32(5), 436-470. https://doi.org/10.1002/er.1375
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1
A sustainable energy future:
Construction of demand and renewable energy supply scenarios.
Bent Sørensen
*
Roskilde University. Department of Environmental, Social and Spatial Change, Energy. Environment and Climate Research Group
Universitetsvej 1, Bld. 11.2, PO Box 260, DK-4000 Roskilde, Denmark
SUMMARY
The creation of energy scenarios, usually describing future situations of interest, involves three steps: 1: Determining
the activities in the target society that involves energy of one or another form. Examples of carrying out such an analy-
sis are presented, with end-use demands distributed on energy forms (qualities) as the deliverable outcome. 2: Deter-
mining the available energy resources in the society in question. This is done for renewable energy resources and pre-
sented as potential energy supply, with a discussion of the aggressivity of exploiting such sources. Finally 3: Matching
demand and supply under consideration of the energy forms needed, with use of intermediate conversions, storage and
transmission, and signaling unused surpluses that may be exported from the society in consideration, or deficits that
have to be imported. An example of such a matching is presented in an accompanying article.
KEY WORDS
: scenario technique, energy modelling, demand analysis, supply assessment, resource appraisal
1. ENERGY SYSTEM MODELLING – GENERAL CONSIDERATIONS
The aim of the present work is to model a range of options for the future energy system of a given
society, say a country, with consideration of the surrounding energy systems (such as those of
neighbouring countries) that may come into play by exchange of energy including purchase of fuels
or other energy services. Due to the considerable inertia in the system, caused by existing equip-
ment and infrastructure, the time horizon is chosen as around fifty years, in order to capture the pos-
sibility of a complete change in the mix of energy sources and the ways of converting, transmitting
and using energy in society. It is thus the target of the study to provide material for decision-makers
that may help them in selecting an optimal energy solution with high economic benefits for the so-
ciety in question. On the other hand, going thus far into the future induces uncertainties and necessi-
tates the formulation of assumptions that may turn out to be incorrect. For this reason, the method-
ology selected is that of scenario analysis, renouncing on finding a single optimal solution and in-
stead analysing a number of alternative scenarios for their advantages and disadvantages. This will
enable decision-makers to apply their preferred weights describing the importance of various factors
such as direct economy, environmental impacts including climate change, supply security and ro-
bustness against (at least some) errors in assumptions. The scenarios contemplate a number of solu-
tions based on equipment or strategy not fully developed or tested. Although surprises in terms of
new solutions appearing within the planning period are possible, the method employed makes them
less probable, because the 50-year horizon is short enough to make it highly likely that all technolo-
gies that can be made ready within that period are already known at present, in some (possibly
early) stage of development and readiness.
*
E-mail: boson@ruc.dk. Web: energy.ruc.dk. Support from the Energy Research Programme of the Danish Energy
Agency (EFP-033001/33031-0021) is acknowledged.
Received 4. February 2007
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2. ENERGY SYSTEM MODELLING – METHODOLOGY
2.1 Demand options
The definition of energy demand used here is true end-use energy, i.e. the energy derived after the
final conversion taking place at the end-user for supplying some demanded energy service. This
energy can be defined rigorously once the demand of energy services is determined, on the basis of
a vision of the activities of the future society (Sørensen, 2004, Chapter 6).
This definition is independent of the efficiency of the possibly several energy conversion steps tak-
ing place between primary energy and end-use energy service. These important aspects will be dis-
cussed in section 2.2, and together with the end-use energy they determine the entailed requirement
for primary energy supplies.
In order to model energy trade between the country focussed upon and its neighbours, the patterns
of surplus and deficit must be determined (as function of time) for each region. This implies that
demand scenarios and conversion efficiency assumptions have to be made not only for say Den-
mark, but also for the energy exchange partners such as the Nordic countries and Germany, which
are already connected to Denmark by electric power grids. If the primary interest is on a single
country, the demand models for the neighbouring countries do not have to be as detailed as for the
primary country, but in many cases, simultaneous studies of a croups of countries with energy-
connections is the objective.
The following is a list of relevant precursor end-use demand scenarios, using Denmark and its
neighbouring countries as an example but still retaining a level of generality. By “precursor scenar-
ios” is meant a set of preliminary scenarios, out of which final scenarios may be selected for closer
investigation. The basis for the precursor scenarios are assumptions regarding desirable activity
levels and energy intensities of the activities, as they have appeared in the energy debates in recent
years, in Denmark and in Europe broadly. They claim no completeness, but try to display enough
diversity to serve as a useful span of the challenges facing the energy planner. Out of these, a more
limited number of scenarios will typically subsequently be selected or reformulated for closer dis-
cussion and concrete simulation efforts.
a) Run-away precursor scenario.
In the run-away scenario, the energy demand grows at least as quickly as the overall economic ac-
tivity (measured e.g. by the gross national product). This has historically been the case during peri-
ods of exceptionally low energy prices, notably in the years around 1960. Conditions for this sce-
nario, in addition to low energy prices, would include measures such as encouraging transportation
work (many passenger-kilometres facilitated by more roads, cheap air connections and decentralisa-
tion of the locations of homes, work places and leisure facilities, many ton-kilometres of freight
haul facilitated by decentralisation of component production and shipment of small-size cargos). In
the building sector, more square metres of living space and more square metres per unit of eco-
nomic activity, and in the electricity sector, more appliances and other equipment. Building style
developments could create a perceived need for air conditioning and space cooling. For industry,
there could be increased emphasis on energy-intensive production, although this is hardly relevant
for countries such as Denmark. However, service sector activities and their energy use could in-
crease substantially, with retail shopping areas greatly increased and use of business-promotion by
light and other energy-demanding displays. For leisure activities, traditional nature walks or swim-
3
ming could be replaced by motocross, speedboat use and other energy-demanding activities, similar
to the habits already seen to expand in North America.
b) High energy-growth precursor scenario.
The high energy-growth scenario is similar to the run-away scenario, but with a slower increase in
energy demand. This could in the transportation sector be due to a certain saturation tendency in
transport activities, due to higher value placed on the time lost in travelling on more congested
roads and in more congested air space. For industry, continued decrease in energy-intensive produc-
tion may lead to a demand growing less than the economic activity. In buildings, heat use may in-
crease less than floor area, due to zoning practices etc. Generally, activity level and energy demand
may see a certain amount of decoupling, reflecting the fact that the primary demands of a society
are goods and services, and that these can be provided in different ways with different energy im-
plications. A certain effect of this type damps the energy demand in the high energy-growth sce-
nario as compared with the run-away scenario, but due more to technological advances and altered
Danish industry mix than to a dedicated policy aimed to reduce energy demand.
c) Stability precursor scenario.
The stability scenario assumes that the end-use energy demand stays constant, despite rearrange-
ments in specific areas. Specifically, the energy demand in the building sector is assumed to satu-
rate (considering that the number of square metres per person occupying the building, whether for
work or living, will not continue to increase, but reach a natural limit with enough space for the
activities taking place, but not excessive areas to clean and otherwise maintain). In the industry sec-
tor, an increasingly knowledge-based activity will reduce the need for energy-intensive equipment,
replacing it primarily by microprocessor-based equipment suited for light and flexible production.
Industrial energy use will decline, although industry like the service and private sectors will con-
tinue to add new electronic equipment and computers. In other sectors, dedicated electricity demand
will increase substantially, but in absolute terms more or less compensated for by the reductions in
the industry sector. For transportation, saturation is assumed both in number of vehicles and number
of passenger- or ton-kilometres demanded, for the reasons outlined above (in the section on the high
energy growth scenario). Reasons for considering this possible could include the replacement of
conference and other business travel by video conferencing, so that an increase in leisure trips may
still be included. Presumably, there has to be planned action for this to be realistic, including aban-
doning tax-rebates for commercially used vehicles and for business travel, and possibly also efforts
in city planning to avoid the current trend of increasing travel distances for everyday shopping and
service delivery. The stability scenario was used as the only energy demand scenario in an earlier
study on the possibilities for hydrogen in the Danish energy system (see Sørensen et al., 2001;
2004, Sørensen, 2005).
d) Low energy-demand precursor scenario
In the low energy-demand scenario, full consideration is paid to the restructuring of industry as-
sumed for countries such as Denmark, from goods-orientation to service-provision. Already today,
many Danish enterprises only develop new technology and sometimes test it on a limited Danish
market: once the technology is ready for extended markets, the production is transferred to other
companies, usually outside Denmark. This change in profit-earning activities has implications for
the working conditions of employees. Much work can be performed from home offices, using com-
puter equipment and electronic communications technology and thereby greatly reducing the de-
mand for physical transportation. Also in the retail food and goods sector, most transactions be-
tween commerce and customer will be made electronically, as it is already the case in a number of
sub-sectors today. An essential addition to this type of trade is the market for everyday products,
where the customers until now has made limited use of electronic media to purchase grocery and
4
food products, probably by reasons of a perceived need to e.g. handle the fruit to see that it is ripe
before buying it. Clearly, better electronic trade arrangements with video inspection of actual prod-
ucts could change the reservations of current customers. If everyday goods are traded electronically,
the distribution of such goods will also be changed to an optimal dispatch requiring considerably
less transport energy that today’s personal shopping. All in all, a quite substantial reduction in en-
ergy demand will emerge as a result of these changes, should they come true. The economic devel-
opment is further de-coupled from energy use and may continue to exhibit substantial growth.
e) Catastrophe precursor scenario.
In the catastrophe scenario, a reduced energy demand is due to the failure to achieve a desirable
economic growth. In the case of Denmark, reasons could be the current declining interest in educa-
tion, particularly in those areas most relevant to a future knowledge society. In this scenario there
would be a lowering of those enabling skills necessary for participating in the international industry
and service developments, and the alternative of importing these intellectual skills is seen as having
been missed by an immigration policy unfavourable to precisely the regions of the world producing
a surplus of people with technical and related creative high-level education. Although there are pes-
simists that see this scenario as the default, i.e. the situation Denmark is moving towards unless
strong policy measures are taken in the near future, the stance here is that the traditional openness of
the Danish society will also this time work to overcome the influence of certain negative elements.
A key reason that this may be likely is the smallness of the Danish economy in the global picture,
implying that even if Denmark should choose to concentrate on less education-demanding areas
such as coordination and planning jobs in the international arena (requiring primarily language and
overview skills), these could easily provide enough wealth to a nation of open-minded individuals
willing to serve as small wheels in larger international projects. This would make the economic de-
cline a passing crisis to be followed by the establishing of a small niche existence for Denmark,
which in energy terms would imply returning to one of the central scenarios described above. Only
in case Denmark becomes internationally isolated, will this option fade away and the catastrophe
scenario become reality. For other countries, some aspects of these threats are also evident, but the
discussion will have to be repeated for each country on its specific premises.
2.2 Energy conversion system
Countries such as Denmark have a long tradition for placing emphasis of efficient conversion of
energy. Following the 1973/4 energy crises, particularly detached homes (where the occupants are
also the owners making decision on investments) were retrofitted to such an extent that the overall
low-temperature heat use in Denmark dropped by 30% over a decade. CO
2
- and pollution-taxes on
electricity has probably been a significant cause of the appliance-purchasing pattern, where the low-
est energy-consuming equipment has taken a dominant part of the market. The same trend is at least
partially seen in automobile purchasing, where a non-linear energy-efficiency dependent annual
registration tax has made the sale of the most energy-efficient vehicles much higher in Denmark
than in other European countries with similar fuel costs. This trend is only partial, because there is
still a substantial sale of luxury cars and 4-wheel-drive special utility vehicles not serving any ap-
parent purpose in a country with hardly any non-paved roads. If the initial registration tax on auto-
mobiles were similarly made energy efficiency-dependent, the effect would be much greater. The
Danish utilities are known for constructing some of the highest-efficiency conventional power-and
heat plants in the world (using coal, natural gas and wood scrap or other biomass-based fuels), and
Danish wind turbines are also known for high efficiency. The transmission losses are fairly low, but
Denmark currently has a smaller coverage with underground coaxial cables that many other Euro-
