The most optimistic of the four in-depth scenarios projects renewable energy accounting for as much as 77% of the world’s energy demand by 2050, amounting to about 314 of 407 Exajoules per year. As a comparison, 314 Exajoules is more than three times the annual energy supply in the United States in 2005, which is also a similar level of supply on the Continent of Europe according to various government and independent sources.

Range in recent levelized cost of energy for selected commercially available RE technologies in comparison to recent non-renewable energy costs. Technology subcategories and discount rates were aggregated for this figure. Source: SRREN. Click to enlarge.

77% is up from just under 13% of the total primary energy supply of around 490 Exajoules in 2008. Each of the scenarios is underpinned by a range of variables such as changes in energy efficiency, population growth and per capita consumption. These lead to varying levels of total primary energy supply in 2050, with the lowest of the four scenarios seeing renewable energy accounting for a share of 15% in 2050, based on a total primary energy supply of 749 Exajoules.

According to the four scenarios analyzed in detail, the decadal global investments in the renewable power sector alone range from 1,360 to 5,100 billion US dollars to 2020 and 1,490 to 7,180 billion US dollars for the decade 2021 to 2030. For the lower values, the average yearly investments are smaller than the renewable power sector investments reported for 2009.

The six renewable energy technologies reviewed are:

• Bioenergy, including energy crops; forest, agricultural and livestock residues; and second-generation biofuels;
• Direct solar energy including photovoltaics and concentrating solar power;
• Geothermal energy;
• Hydropower, including run-of-river, in-stream or dam projects with reservoirs;
• Ocean energy, ranging from barrages to ocean currents and ones which harness temperature differences in the marine realm; and
• Wind energy, including on- and offshore systems.

The upper end of the scenarios assessed, representing a cut of around a third in greenhouse gas emissions from business-as-usual projections, could assist in keeping concentrations of greenhouse gases at 450 parts per million, the report said. This could contribute towards a goal of holding the increase in global temperature below 2 °C—an aim recognized in the United Nations Climate Convention’s Cancun Agreements.

The findings, launched Tuesday after being approved by member countries of the IPCC in Abu Dhabi, United Arab Emirates, are contained in a summary for policymakers of the Special Report on Renewable Energy Sources and Climate Change Mitigation (SRREN). The summary is a short version of a roughly a thousand page comprehensive assessment compiled by for IPCC’s Working Group III. The full report is scheduled for release on 31 May.

With consistent climate and energy policy support, renewable energy sources can contribute substantially to human well-being by sustainably supplying energy and stabilizing the climate. However, the substantial increase of renewables is technically and politically very challenging.

—Professor Ottmar Edenhofer, Co-Chair of Working Group III

The report shows that it is not the availability of the resource, but the public policies that will either expand or constrain renewable energy development over the coming decades. Developing countries have an important stake in this future—this is where most of the 1.4 billion people without access to electricity live yet also where some of the best conditions exist for renewable energy deployment.

—Ramon Pichs, Co-Chair of the Working Group III

The report will feed into the broader work of the IPCC as it prepares its Fifth Assessment Report (AR5). The AR5 Synthesis Report is scheduled for finalization in September 2014.

The SRREN, approved by government representatives from 194 nations, has reviewed the current penetration of six renewable energy technologies and their potential deployment over the coming decades.

While the report concludes that the proportion of renewable energy will likely increase even without enabling policies, past experience has shown that the largest increases come with concerted policy efforts.

Though in some cases renewable energy technologies are already economically competitive, the production costs are currently often higher than market energy prices. However, if environmental impacts such as emissions of pollutants and greenhouse gases were monetized and included in energy prices, more renewable energy technologies may become economically attractive.

For most of them, costs have declined over the last decades and the authors expect significant technical advancements and further cost reductions in the future, resulting in a greater potential for climate change mitigation.

Public policies that recognize and reflect the wider economic, social and environmental benefits of renewable energies, including their potential to cut air pollution and improve public health, will be key for meeting the highest renewables deployment scenarios.

Increasing the share of renewables requires additional short-term and long-term integration efforts. Studies clearly show that combining different variable renewable sources, and resources from larger geographical areas, will be beneficial in smoothing the variability and decreasing overall uncertainty for the power system.

There is a need for advanced technologies to optimize the infrastructure capacity for renewables. Additionally, there is a need for balancing supply and demand, like advanced demand and supply forecasting and plant scheduling.

Key Findings from the Summary for Policymakers

• Of the around 300 Gigawatts (GW) of new electricity generating capacity added globally between 2008 and 2009, 140 GW came from renewable energy.

• Despite global financial challenges, renewable energy capacity grew in 2009—wind by more than 30%; hydropower by 3%; grid-connected photovoltaics by more than 50%; geothermal by 4%; solar water/heating by more than 20% and ethanol and biodiesel production rose by 10% and 9% respectively.

• Developing countries host more than 50% of current global renewable energy capacity.

• Most of the reviewed scenarios estimate that renewables will contribute more to a low carbon energy supply by 2050 than nuclear power or fossil fuels using carbon capture and storage (CCS).

• The technical potential of renewable energy technologies exceeds the current global energy demand by a considerable amount—globally and in respect of most regions of the world. Under the scenarios analyzed in-depth, less than 2.5% of the globally available technical potential for renewables is used—in other words more than 97% is untapped underlining that availability of renewable source will not be a limiting factor.

• Accelerating the deployment of renewable energies will present new technological and institutional challenges, in particular integrating them into existing energy supply systems and end use sectors.

• A combination of targeted public policies allied to research and development investments could reduce fuel and financing costs leading to lower additional costs for renewable energy technologies.

• Public policymakers could draw on a range of existing experience in order to design and implement the most effective enabling policies—there is no one-size-fits-all policy for encouraging renewables.

Key Renewable Energy Technologies and Their Potential

• Bioenergy technologies can generate electricity, heat and fuels from a range of feedstocks. Some bioenergy systems, including ones that involve converting land into agricultural biomass and energy crops, can generate more greenhouse gas emissions than they save. Others, such as advanced systems converting woody wastes into liquid fuels, can deliver 80% to 90% emission reductions compared to fossil fuels.

  Bioenergy, mainly for traditional cooking and heating in developing countries, currently represents over 10% of global energy supply or ca. 50 Exajoules per year. While the share of bioenergy in the overall renewables mix is likely to decline over the coming decades, it could supply 100 to 300 Exajoules of energy by 2050, the expert review concludes.

• Direct Solar Energy technologies include photovoltaics and concentrating solar power (CSP). They can produce electricity, heat and light. Currently, direct solar contributes only a fraction of one percent to total global energy supply.

  Potential deployment scenarios range from a marginal role of direct solar energy in 2050 to one of the major sources of energy supply. The actual deployment will depend on continued innovation, cost reductions and supportive public policies.

  In the most ambitious climate stabilization scenarios solar primary energy supply by 2050 reaches up to 130 Exajoules per year, which can be attributed to a large extent to photovoltaic electricity generation. In some scenarios, its share in global electricity generation reaches up to a third by 2050, but in the majority of scenarios remains below one tenth.

• Geothermal Energy utilizes heat stored in the Earth’s interior directly or to generate electricity, with currently about 0.7 Exajoule per year. By 2050, geothermal deployment could meet more than 3% of global electricity demand and about 5% of the global heat demand.

  Global geothermal technical potential is comparable to the global primary energy supply in 2008. However, Geothermal Energy does not reach the technical potential limit in any of the scenarios analyzed, with the deployment rate remaining below 5% for both the regional and global level.

• Hydropower projects encompass dam projects with reservoirs, run-of-river and in-stream projects and range from small to large scale. The installed capacity by the end of 2008 contributed 16% of worldwide electricity supply, making hydropower the largest renewable energy source in the electricity sector.

  According to long term scenarios, hydropower’s share in global electricity supply may decrease to 10 to 14%. Despite absolute growth in hydropower supply, the expected energy demand growth and continuing electrification could result in a decreasing share.

• Ocean Energy technologies are diverse and use the kinetic, thermal, and chemical energy of seawater. Most are at the demonstration and pilot project phases. Due to its nascent stage of development, they are unlikely to significantly contribute to global energy supply before 2020.

  Ocean energy is currently only represented in very few scenarios. As shown by the review, projected deployments could result in energy delivery of up to 7 Exajoules per year by 2050.

• Wind Energy’s primary application of relevance to climate change mitigation is to produce electricity from large wind turbines located on land or offshore. The wind power capacity installed by the end of 2009 met close to 2% of worldwide electricity demand.

  The review shows a high expansion rate in Europe, North America and, more recently, in China and India. A greater geographical distribution of deployment is likely to be needed to achieve the higher deployments indicated by the scenario literature. Under the demand projection of some scenarios global wind power share grows to more than 20% by 2050.

Resources

• Special Report on Renewable Energy Sources and Climate Change Mitigation (summary for policymakers)