Bioenergy, Hydropower

Not too late: IPCC identifies renewable energy as a key measure to limit climate change

Issue 4 and Volume 10.

The Intergovernmental Panel on Climate Change (IPCC) recently released the Summary for Policymakers of its Working Group 3 report Climate Change 2007: Mitigation of Climate Change, a document which was painstakingly approved sentence by sentence over 4 days in May 2007 by 120 government delegations in Thailand. Here Ralph Sims brings together its main findings.

The first report in the Intergovernmental Panel on Climate Change (IPCC) 4th Assessment series, by Working Group 1, outlined the latest knowledge on Climate Science. The second, by Working Group 2, covered the possibilities for the Adaptation of ecosystems – glaciers receding, sea level rising, droughts etc. The third report, on Mitigation, attempted to compile the latest scientific knowledge relating to low-carbon emitting technologies; their costs and potentials for greenhouse gas (GHG) emission avoidance; their long-term prospects out to 2100 for stabilizing atmospheric GHGs; a detailed list of policy options; and a discussion of the opportunities for sustainable development and equity linked with GHG abatement. The three short Summaries for Policy Makers (SPM) can be found at with the full reports being released as soon as possible over the next few months.

Overall, the message being delivered by Working Group 3 is a strong but positive one. Action is required. The situation is urgent – but not yet beyond repair. Many energy efficiency and energy supply technologies and practices to reduce greenhouse gas emissions are available now, including renewable energy. And mitigation measures will bring many other benefits, some of which are in fact expected to save money.

On a more negative note, however, the report confirmed that since the 3rd Assessment Report in 2001, GHG emissions continue to rise fast – if not accelerate – and that this is in spite of all the low-carbon technologies available, all the mitigation policies in place, the higher global energy prices and the Kyoto Protocol having come into force. The ‘long, loud and legal’ government policies that would have greatly assisted the more rapid deployment of renewable energy in the past few years have simply not happened except in two or three exceptional countries.

Emissions of the major GHGs covered by the Kyoto Protocol increased by 70% between 1970 and 2004 (Figure 1). Without additional measures, global GHG emissions are expected to continue to rise, reaching somewhere between 25%-90% above 2000 levels by 2030. This is instead of the preferred pathway to peak as soon as practical, then start the downhill trend that is clearly needed if we are to combat climate change.

FIGURE 1. Greenhouse gas emissions from energy-related and all other major sources have increased from around 28 Gt CO2-eq in 1970 to reach nearly 50 Gt CO2-eq in 2004. Note: All gases have been converted to CO2-equivalents based on their comparative global warming potentials.

The IPCC report states: ‘In order to stabilize the concentration of GHG in the atmosphere, emissions would need to peak and decline thereafter. The lower the stabilization level, the more quickly this peak and decline would need to occur. Mitigation efforts over the next two to three decades will have a large impact on opportunities to achieve lower stabilization levels.’

Working Groups 1 and 2 clearly showed that climate change has already begun and some adaptation is inevitable. Our job in Working Group 3 was to try to show how different stabilization levels could be achieved given various possible emission reduction pathways, and at what increased costs on the economy in terms of reduced GDP in each case. So, for example, under a very optimistic scenario, emissions would need to peak within the next decade and then reduce quickly to reach the necessary atmospheric stabilization level of around 445-535 ppm CO2-eq (parts per million of all the GHG by volume converted to carbon dioxide equivalents). This would be a real challenge given that current GHG concentrations in the atmosphere are already at around 430 ppm CO2-eq (including over 370 ppm of CO2), and with no signs of growth slowing down. To achieve stabilization at these levels would cost around 3% of global gross domestic product (GDP) in 2030. Even then this would still give a 2.0°C-2.8°C rise in average temperature above pre-industrial levels, resulting in whatever changes to the world’s climate this would inevitably bring.

Some areas are likely to experience more frequent and severe droughts as a consequence of climate change SXC PHOTO LIBRARY

To stabilize at a higher concentration around 535-590 ppm CO2-eq would need emissions to peak before 2030, and would give a 2.8°C-3.2°C average global temperature rise, but the global cost would be cheaper, at up to 2.5 % of GDP by 2030. If, however, we, as a global society, are prepared to invest no more than 1.2% of our global GDP by 2030 to combat the problem and are then willing to accept the risks of greater climate change events as the result of a 3.2°C-4.0°C temperature rise, then stabilizing atmospheric GHG concentrations at a very high 590-710 ppm would enable emissions to continue to rise till they eventually peaked before 2060. Worldwide carbon prices of around $20-$80/tonne CO2-eq by 2030 would be consistent with this target. (A price of $20/tonne CO2-eq equates to additional costs of around $10/barrel of oil; $0.05/litre of gasoline; $0.02/kWh of coal-fired electricity and $0.006/kWh of gas-fired electricity).

Of course, what the world will be like under these varying temperature increases, what the costs of adaptation and extreme weather events might be in comparison with the costs of mitigation, and what risks society is prepared to take, are the key questions yet to be answered.

What we are now still lacking is any real sense of urgency by government policy makers, given that these IPCC analyses and the UK’s Stern Review earlier this year clearly show that immediate action is advisable. Overall, the message is that given urgent action, acceptable emission reduction targets are achievable by deployment of a portfolio of technologies that are currently available and also by deployment of those that are expected to be commercialized in coming decades.

One other significant finding of the report is that studies from all regions of the world point to substantial health benefits obtained by reducing GHG emissions, especially from renewable energy implementation, because of the associated lower air pollution. So much so, in fact, that the value from the health benefits could offset a substantial fraction of the costs of GHG reductions.

Technology solutions

A wide range of mitigation options using a range of technologies are outlined in the report. The costs and economic potential for each sector (energy supply, transport, buildings, industry, agriculture, forestry and waste) were calculated against being above the baseline reference scenario (which is in effect business-as-usual based on existing policies already in place). Many energy efficiency measures were accounted for in the buildings, industry and transport chapters to give considerable economic potential opportunities for categories up to $20, $50 or $100/tCO2-eq, (Figure 2) and some even for net cost benefits (i.e. below $0/tCO2-eq). Where any electricity savings occurred (such as replacing incandescent light bulbs), then these were allocated to the appropriate sector (such as buildings) and not double counted in the energy supply sector.

FIGURE 2. Estimated sectoral economic potential for global mitigation for OECD, economies in transition (EIT) and developing country regions as a function of carbon price in 2030 compared to the baseline of the Reference scenario from the IEA World Energy Outlook, 2004.

The Energy Supply chapter included key mitigation technologies and practices currently commercially available, such as improved generation plant efficiency, better distribution, fuel switching from coal to gas, nuclear power, combined heat and power (CHP), early applications of carbon dioxide capture and storage (CCS) such as removing and storing CO2 from natural gas and renewable heat and power. In addition, key technologies likely to become commercial before 2030 were included in the analysis of future mitigation potentials. These included CCS for coal-, gas-, and biomass-fired power generation plants; advanced nuclear power designs; ocean energy systems; concentrating solar power and solar photovoltaics.

TABLE 1. Generalized data for selected global energy resources (including potential reserves), annual rate of use (from a total of 490 EJ in 2005), share of total primary energy supply in 2005, and comments on associated environmental impacts. (Data aggregated from numerous sources.)

So-called ‘geo-engineering options’ which hit the headlines from time to time, such as inserting material into the upper atmosphere to block sunlight, are described as ‘largely speculative and unproven, and with the risk of unknown side-effects’. More practically perhaps, the report says: ‘Investments in the worldwide deployment of low-GHG emission technologies as well as technology improvements through public and private research, development and demonstration would be required for achieving stabilization targets as well as cost reductions.’ This is where renewable energy has a considerable role to play.

Renewable energy options

Fossil fuels can be partly replaced by renewable energy sources to provide heat (from biomass, geothermal or solar), electricity (from hydro, wind, geothermal, bioenergy, solar PV and concentrating solar power), CHP plants and transport fuels. Ocean energy is still immature and was assumed unlikely to make a significant contribution to overall power needs by 2030. Net GHG emissions avoided were used in the analysis since most renewable-energy systems emit small amounts of GHG from the fossil fuels used for manufacturing, transport, installation and from any cement or steel used in their construction. Overall, net GHG emissions are generally low for renewable-energy systems (Figure 3) with the possible exception of some biofuels for transport, where fossil fuels are used to grow the crop and process the biofuel.

FIGURE 3. GHG emission comparisons for 1 GWh of electricity generated by alternative power generation technologies, including coal and gas plants with CCS attached.

An attempt was made to compare the wide range of energy resources in terms of their environmental resource (based on a large number of references in the literature) (Table 1). (Note several energy sources included in the report have not been included in the tables shown here). Similarly, some comparative indication of present and projected cost ranges were considered (Table 2). The wide range depicts the national/regional resource variations. Ideally, each country and state will undertake its own analysis to determine its specific mitigation costs and potential for emission reductions using this IPCC report as a guide.

Mitigation potential in the electricity sector

For the electricity generation sector, the IEA World Energy Outlook ‘Reference scenario’ was used as a baseline to start the analysis (Figure 4). The energy related CO2 emissions in 2002 were around 9.5 Gt CO2 and projected to rise to around 16 Gt CO2 by 2030 as electricity demand increases from 16,074 TWh in 2002 to a projected 31,650 TWh by 2030 under ‘business-as-usual’ based on existing policies. Although electricity demand doubles, the Gt CO2 emissions do not due to a changing mix of generation technologies as assumed in this baseline.

The potentials for energy efficiency measures in the building and industry sectors (Figure 2) could reduce the demand for electricity from 31,650 TWh to around 22,000 TWh by 2030, thereby reducing emissions to around 10 Gt CO2 (Figure 4). Detailed analyses were undertaken for each technology to provide an indication of the increased capacity of new plants needed to meet growing demand; the capacity for new plants needed to replace existing stock turning over at the end of plant life; and the existing power plants assumed to be remaining in operation by 2030. The potential rate of build for nuclear, wind, ocean energy, etc (including constraints from inadequately trained personnel) were taken from the literature where possible and used to assess the electricity supply mix by 2030.

FIGURE 4. Increase in electricity sector carbon dioxide emissions in the IEA World Energy Outlook (2004) baseline from 2002 to 2030. The projection is reduced by energy efficiency, substitution for fossil fuelbased generation and the uptake of CCS after 2015, all for <$50/tCO2.

CCS was assumed not to be fitted to new commercial power plant until after 2015 and then with relatively slow growth up to 2030. Concentrating solar power (CSP) plants were assumed to be more widely deployed over this period and geothermal too, though this was constrained to 2% of electricity demand due to suitability of locations, resource consents etc.

Overall, the assumptions for a carbon price of up to $50/t CO2-eq showed that nuclear power would increase from 16% of total power generation today to 18% of an expanded market by 2030. Renewable energy at 18% today (mainly large hydro) would also increase, taking a market share of around 35% by 2030. CCS would be associated with around 6% of total generation by that time. Thus, fossil fuel generation without CCS would then account for around 42% of power generation (Figure 4), and the GHG emissions from the power sector would be reduced accordingly.

So the potential is there for halving the 2002 emissions from the electricity sector given the appropriate policies to encourage energy efficiency and a transition to low carbon-emitting technologies.

Renewable energy potentials

In the report, all relevant renewable energy technologies are described in detail and reasons provided for their assumed contribution to the energy supply mix by 2030. Of the 35% share of electricity from renewable energy as projected by 2030, large and small hydro could provide around half; wind around a fifth; bioenergy also a fifth (but with a possibly greater share from adding in CHP that was not able to be analysed in detail in the report due to a lack of data in the literature); geothermal at around one twentieth (again with a possible increase from CHP applications); and CSP and solar PV having a similar combined contribution of around one twentieth.

TABLE 2. Present and projected costs ($2006) in 2030 for a range of energy resources and carriers.

Assessing the renewable energy potentials from renewable energy heating and cooling technologies was not possible simply because there is insufficient data available. Some countries have managed to ascertain the total installed boiler capacity of heat plants, achieved by surveying the name-plates of the equipment. However, since a given boiler could be run for 10, 100 or 8000 hours a year, the amount of heat energy actually provided by a boiler in a year is usually not metered. The diverse nature of heat plants makes assessment of the energy use very difficult.

Biomass and bioenergy

This is such a wide ranging topic that a cross-cutting group was established across Working Group 3 chapters to identify how much biomass might become available by 2030 and whether this would meet the projected bioenergy demand. Biomass can be sourced from industry, agriculture, forestry and wastes, so each chapter (7, 8, 9 and 10) provided an assessment of the biomass resource available for energy purposes (allowing for competition for land use, water, chemicals and materials). Conversion of the biomass into useful bioenergy was covered in chapter 4 and the bioenergy as used for the transport, buildings and industry sectors (chapters 5, 6 and 7) was then assessed. Based on this ‘bottom-up’ approach it appears there will be sufficient biomass available up to at least 2030 to meet the growing demand for bioenergy products and services. Each country has individually to consider competition for land and water use, whether the biomass is produced on a sustainable basis, the supply chain logistics, future markets, etc.

Biofuels were a key part of the analysis, with land use, resource availability, water constraints, second generation biofuels, possible blends with gasoline and diesel all under evaluation. The result was a projection that biofuels will increase from their current 1% share of road transport fuels to around 5%-10% by 2030. Any CO2 savings could become partly offset if other liquid transport fuels such as coal-to-liquids, oil sands, etc. also gained an increasing market share.

In summary

Energy efficiency is often cheaper than increasing energy supply and could significantly reduce CO2 emissions and save money, particularly from buildings.

For the energy supply sector, investment in energy infrastructure is projected to be at least US$20 trillion between now and 2030. Decisions made relating to heat and power plant selection will have long term impacts on GHG emissions due to the slow rate of stock turnover.

Improved vehicle efficiency generally brings benefits and lower costs, but other consumer considerations come into play. Market forces alone, including rising fuel costs, are therefore not expected to lead to significant emission reductions.

FIGURE 5. The biomass resource from several sources is converted into a range of products for use by the transport, industry and building sectors.

Biofuels are projected to supply 3% of transport fuel by 2030, but changes in fuel prices and technology developments might boost this to up to 10%.

By 2020, about 30% of the projected GHG emissions in the building sector can be avoided ‘with net economic benefit’ since around one third of the potential is below $0/tCO2-eq.

Post-consumer waste contributes less than 5% of global GHG emissions, but mitigation action is possible at ‘low cost’ and it could also promote sustainable development. Waste-to-energy is often a useful bioenergy solution to waste treatment and disposal.

Changes in lifestyles and consumption patterns that emphasize renewable energy and resource conservation can contribute to developing a low-carbon economy that is both equitable and sustainable.

Ralph E. H. Sims is Professor of Sustainable Energy, Massey University, New Zealand
e-mail: [email protected]

The author of this article was the co-ordinating lead author of the chapter team for Energy Supply over the 3 year writing and review process. Of the 13 chapters in the report, this one received the greatest attention, with over 5000 review comments that were responded to, and with the sections on nuclear and renewable energy receiving a major share of them.