CEE April-June 2012

by 50 to 85 per cent below 2000 levels by 2050 and begin to decrease (rather than continuing current increase) no later than 2015. Fie 2. Slura of aousY_,_ ia coul alobaJ primuy mUJY tupply In 2008 (492 ~). Data ..rce LEA (ZOIOa). Drivers of carbon dioxide emissions Since about 1850, c... u.a pcrcm< global use of fossil fuels Nucbrl.O (coal, oil and gas) has pcrano increased to dominate energy supply (Figure 1), both replacing many traditional uses of bio-energy and providing new services. The rapid rise in fossil fuel combustion (including gas flaring) has produced a corresponding rapid growth in C0 2 emissions. The amount of carbon in fossil fuel reserves and resources (unconventional oil and gas resources as well as abundant coal) not yet burned has the potential to add quantities of C0 2 to the atmosphere - if burned over coming centuri es - that would exceed the range of any of the scenario considered. Renewable energy to mitigate climate change Renewable energy (RE) supply sources are effective in lowering C0 2 emissions because they have low carbon intensity with emissions per unit of energy output typically 1 to 10 per cent that of fossil fuels. On a global basis, it is estimated that RE accounted for 12.9 per cent of the total 492 exajoule (1EJ = 1018 joule) of primary energy supply in 2008. The largest RE contributor was biomass (10.2 per cent), with the majority (roughly 60 per cent) of the biomass fuel used in traditional cooking and heating applications in developing countries, but with rapidly increasing use of modern biomass as well. Hydropower represented 2.3 per cent, whereas other RE sources accounted for 0.4 per cent. In 2008, RE contributed approximately 19 per cent of global electricity supply (16 per cent hydropower, 3 per cent other RE). Global electricity production in 2008 was 20181 TWh (or 72.65 EJ). Deployment of RE has been increasing rapidly in recent years. Under most conditions, increasing the share of RE in the energy mix will require policies to stimulate changes in the energy system. Government policy, the declining cost of many RE technologies, changes in the prices of fossil fuels and other factors have supported the continuing increase in the use of RE. While RE is still relatively small, its growth has accelerated in recent years. In 2009, despite global financial challenges, RE capacity continued to grow rapidly, induding wind power (32 per cent added), hydropower (3 per cent added), grid-connected photovoltaics (53 per cent added), geothermal power (4 per cent added) and solar hot water/heating (21 per cent added) (REN 21 2010). Biofuels accounted for 2 per cent of global road Dir«t Solar En.rgy 0.1 per «nt En.rgy 0.002 per""" transport fuel demand in 2008 and nearly 3 per cent in 2009. The annual production of ethanol increased to 1.6 EJ (76 billion litres) by the end of 2009 and biodiesel production increased to 0.6 EJ(17 billion litres). Of the approximate 300 gigawatts (GW) of new electridty generating capacity added globally over the two years period from 2008 to 2009, 140 GW came from RE additions. Collectively, by the end of 2009 developing countries hosted 53 per cent of global RE power generation capacity (including all sizes of hydropower), with China adding more capacity than any other country in 2009. The USA and Brazil accounted for 54 and 35 per cent of global bioethanol production in 2009, respectively, while China led in the use of solar hot water. At the end of 2009, the use of RE in hot water/heating markets included modern biomass (270 GWth), solar (180 GWth) and geothermal (60 GWth). The use of RE (excluding traditional biomass) in meeting rural energy needs is also increasing, including small hydropower stations, various modern bioenergy options and household or village PV, wind or hybrid systems that combine multiple technologies (Figure 2). Most RE technologies have low specific emissions of C0 2 into the atmosphere as compared to fossil fuels, which makes them useful tools for addressing climate change. For a RE resource to be sustainable, it must be inexhaustible and must not damage the delivery of environmental goods and services including the climate system. For example, to be sustainable, biofuel production should increase net C0 2 emissions, should not adversely affect food security, or require excessive use of water and chemicals or threaten biodiversity. To be sustainable, energy must also be economically affordable over the long term; it must 37