Renewable energy technologies have the potential to meet world energy demand many times over and are now ready for use on a large scale. Wind and solar power are the fastest- growing energy sources in the world. By some estimates, "new renewables" (which excludes large-scale hydropower and traditional biomass) already account for more than 100,000 megawatts (MW) of grid-connected electric capacity. Globally, new renewable energy supplies the equivalent of the residential electricity needs of more than 300 million people.

In 1999, the International Energy Agency noted that

The world now uses 10 times as much wind energy as it did only a decade ago, and solar power consumption has risen sevenfold. Political support for renewables is on the rise as well. Several countries have recently passed strong new legislation to support renewable energy, opening markets in a rapidly growing list of countries.

In fact, the European Union (EU) has established a target for renewables of 12 percent of total energy by 2010. National goals in Germany and Denmark have helped stimulate rapid wind power development that has in turn led to more ambitious goals. The Danish company BTM Consult, which projects that wind power could supply 10 percent of global electricity by 2020, argues that nations should set wind-specific goals, backed up by legally enforced mechanisms such as those now popular in Europe. The United States aims to increase wind power's share of electricity to 10 percent by 2010—compared with about 0.1 percent today—but it has yet to provide such policy support.

The forces for and against change were on full display at the World Summit on Sustainable Development, held in Johannesburg, South Africa, in summer 2002. The European Union and Brazil proposed the adoption of specific numerical targets for the use of new renewable energy worldwide. Strong opposition arose from the fossil fuel industry and from the governments of most oil- producing nations and major fossil fuel users such as China and the United States. The battle in Johannesburg ended in a watered-down, non-numerical goal to increase renewable energy use. But while the world is sharply divided on what kind of energy future must lie ahead, many nations now view renewable energy as a credible alternative to fossil fuels.

The rapid expansion of renewable technologies over the past decade has been fuelled by a handful of countries that have adopted ambitious and deliberate government policies aimed to advance renewable energy. These successful policy innovations have been the most important drivers in the advancement and diffusion of renewable technologies such as wind and solar photovoltaics (PVs).

The ultimate step in the decarbonization process is the production and use of pure hydrogen. As noted earlier, the gradual displacement of carbon by hydrogen in energy sources is well under way. Between 1860 and 1990, the ratio of hydrogen to carbon in the world energy mix increased more than sixfold.

Hydrogen—the universe's lightest and most abundant element—is known most commonly for its use as a rocket fuel. It is produced today primarily from the steam reformation of natural gas for a variety of industrial applications, such as the production of fertilizers, resins, plastics, and solvents. Hydrogen is transported by rail, truck, and pipeline and stored in liquid or gaseous form. Though it costs considerably more to produce than petroleum today, the prospect of hydrogen becoming a major carrier of energy has been revived due to advances in another space-age technology: the fuel cell.

An electrochemical device that combines hydrogen and oxygen to produce electricity and water, the fuel cell was first used widely in the U.S. space programme and later in a number of defense applications such as submarines and jeeps. While these cells were traditionally bulky and expensive, technical advances and size and cost reductions have sparked interest in using them in place of internal combustion engines (ICEs), central power plants, and even portable electronics.

Nongovernmental organizations, working with local communities, can make a difference on a small scale, as in Thailand, but alone they will not bring about the transformation necessary for movement toward a renewably powered world.

Additional environmental costs of conventional energy production and use include destruction wrought through resource extraction; air, soil, and water pollution; acid rain; and biodiversity loss. Conventional energy requires vast quantities of fresh water. Mining and drilling affect the way of life and the very existence of indigenous peoples worldwide. In China, the environmental and health costs of air pollution, due mainly to coal burning, totaled approximately 7 percent of gross domestic product (GDP) in 1995. The World Bank estimates that under business as usual, these costs could rise to 13 percent of China's GDP by 2020. After a decade-long study, U.S. and European researchers calculated that the environmental and health costs associated with conventional energy are equivalent to 1-2 percent of the European Union's annual GDP, and that the price paid for conventional energy is significantly lower than its total costs.  These estimates do not include the costs of climate change— potentially the most expensive consequence. Global economic losses due to natural disasters, which are in line with events anticipated as a result of global warming, appear to be doubling with each decade, and annual losses from such events are expected to approach $150 billion over the next 10 years.

The direct economic and security costs associated with conventional energy are also substantial. Nuclear power is one of the most expensive means of generating electricity, even without accounting for the risks of nuclear accidents, weapons proliferation, and problems associated with nuclear waste. Political, economic, and military conflicts over limited resources such as oil will become more significant as demand increases worldwide. Similarly, the price of fossil fuels will become increasingly erratic as demand rises and conflicts rage in oil- rich regions, which in turn would affect the stability of economies around the world. The economic costs of relying on imported fuels are extremely high—it is estimated that African countries spend 80 percent of their export earnings on imported oil. Likewise, the benefits of reducing imports can be significant. If not for Brazil's 25-year ethanol program, which now displaces 220,000 barrels of oil per day, the country's foreign debt would be about $140 billion higher, according to one estimate.

Some governments are striving to surpass Kyoto goals and take a longer- term perspective. The United Kingdom has a goal of cutting its carbon emissions to 20 percent below 1990 levels by 2010. In March 2000, the government unveiled a new package of policies including a climate change levy, negotiated agreements with energy-intensive sectors and car manufacturers, and a requirement that electricity suppliers generate at least 10 percent of their power with renewable energy sources. An expert committee appointed by the Swedish government has looked even further ahead and mapped out a long-term national strategy for halving greenhouse gas emissions by 2050. Key parts of the plan include tighter efficiency regulations for housing, industry, and offices; the introduction of a car tax; and the expansion of subsidies for wind power.

Decarbonization may be an especially useful concept for developing countries. As experience with industrial nations has shown, emission "baselines"—the starting point against which trends are measured— using net emissions can be highly problematic because they are subject to changes in economic growth rates. This is even more so for developing nations, where emissions trends have been volatile in recent years. A 1999 U.N. Development Programme (UNDP) study asserts that "baselines constructed using carbon emissions per unit GDP...tend to be less variable and less subject to factors beyond the control of policymakers, and arc thus a better indicator of whether a country is continuing to make progress in de-coupling emissions from economic development."

The UNDP study, which contains casestudies of Argentina, Brazil, China, India, Mexico, and several African nations, finds that these countries are slowing emissions growth through a range of policies adopted more for their social, economic, and environmental benefits—energy savings, lower air pollution, reduced oil imports—than for their carbon cuts. This suggests a seemingly counter-intuitive lesson for all nations: that it may be easier to implement decarbonization policies when their non-climate benefits are emphasized.