Moving from principles to action on energy supply and climate change mitigation requires a long-term perspective. Energy infrastructure takes time to build up; new energy technologies take time to develop. Policy shifts often also need many years to take effect. Any analysis that seeks to tackle energy and environmental issues therefore needs to look ahead at least half a century.

Scenarios are important in describing possible development paths, to give decision-makers an overview of future perspectives and to indicate how far they can shape the future energy system. Two different kinds of scenario are used here to characterize the wide range of possible pathways for a future energy supply system: a Reference scenario, reflecting a continuation of current trends and policies, and the Energy [R]evolution (E[R]) scenarios, which are designed to achieve a set of dedicated environmental policy targets.

The Reference scenario is based on the reference scenario published by the International Energy Agency (IEA) in World Energy Outlook 2009 (WEO 2009).91 The Reference scenario only takes existing international energy and environmental policies into account. Its assumptions include, for example, continuing progress in electricity and gas market reforms, the liberalization of cross-border energy trade, and recent policies designed to combat environmental pollution. The Reference scenario does not take into consideration additional mechanisms to reduce greenhouse gas emissions, beyond what are already in place or planned. As the IEA’s projection only covers a time horizon up to 2030, the Reference scenario has extended that horizon by extrapolating key macroeconomic and energy indicators forward to 2050. This provides a baseline for comparison with the Energy [R]evolution scenarios.

The Energy [R]evolution scenario has a key target of reducing worldwide carbon dioxide emissions down to a level of around 10 gigatonnes per year by 2050, in order to keep the increase in global temperature under +2°C. A second objective is the global phasing-out of nuclear energy. First published in 2007, then updated and expanded in 2008, this latest revision of the E[R] scenario also serves as a baseline for the more ambitious Advanced Energy [R]evolution scenario. To achieve its targets, the Advanced scenario is characterized by significant efforts to fully exploit the large potential for energy efficiency, using currently available best-practice technology. At the same time, all cost-effective renewable energy sources are used for heat and electricity generation as well as the production of biofuels. The general framework parameters for population and GDP growth remain unchanged from those of the Reference scenario.

The Advanced Energy [R]evolution Scenario is aimed at an even stronger decrease in CO2 emissions, especially given the uncertainty that even ten gigatonnes allowed per year might be too much to keep global temperature rises at bay. All general framework parameters, such as population and economic growth, remain unchanged. The efficiency pathway for industry and “other sectors” is also the same as in the basic Energy [R]evolution scenario. What is different is that the Advanced scenario incorporates a stronger effort to develop better technologies to achieve CO2 reduction. So the transport sector factors in lower demand (compared to the basic scenario), resulting from a change in driving patterns, a faster uptake of efficient combustion vehicles, and—after 2025—a larger share of electric and plug-in hybrid vehicles.

Given the enormous and diverse potential for renewable power, the Advanced scenario also foresees a shift in the use of renewables from power to heat. Assumptions for the heating sector therefore include a faster expansion of the use of district heat and hydrogen, and more electricity for process heat in the industry sector. More geothermal heat pumps are also used, which leads, combined with a larger share of electric drives in the transport sector, to a higher overall electricity demand. In addition, a faster expansion of solar and geothermal heating systems is assumed.

In all sectors, the latest market development projections of the renewables industry92 have been taken into account (see Table 5.11: “Assumed annual average growth rates for renewable energy technologies”). In developing countries in particular, a shorter operational lifetime for coal power plants, of 20 instead of 40 years, has been assumed in order to allow a faster uptake of renewables. The speedier introduction of electric vehicles, combined with the implementation of smart grids and faster expansion of super grids (about ten years ahead of the basic Energy [R]evolution scenario) allows a higher share of fluctuating renewable power generation (photovoltaic and wind) to be employed. The 30% mark for the proportion of renewables in the global energy supply is therefore passed just after 2020—ten years ahead of the basic Energy [R]evolution scenario.

The global quantities of biomass and large hydro power remain the same in both Energy [R]evolution scenarios, for reasons of sustainability.

These scenarios by no means claim to predict the future; they simply describe three potential development pathways out of the broad range of possible “futures.” The Energy [R]evolution scenarios are designed to indicate the efforts and actions required to achieve their ambitious objectives and to illustrate the options we have at hand to change our energy supply system into one that is sustainable.

5.1 scenarios background

The scenarios in this report were jointly commissioned by Greenpeace and the European Renewable Energy Council from the Institute of Technical Thermodynamics, part of the German Aerospace Center (DLR). The supply scenarios were calculated using the MESAP/PlaNet simulation model adopted in the previous Energy [R]evolution studies. Some detailed analyses carried out during preparation of the 2008 Energy [R]evolution study were also used as input to this update. The energy demand projections were developed for the 2008 study by Ecofys Netherlands, based on an analysis of the future potential for energy efficiency measures. The biomass potential, judged according to Greenpeace sustainability criteria, has been developed especially for these scenarios by the German Biomass Research Centre. The future development pathway for car technologies is based on a special report produced in 2008 by the Institute of Vehicle Concepts, DLR for Greenpeace International. For details on these studies, as well as the assumptions on population and economic growth rates, see the 2010 global Energy [R]evolution report.