杏吧原创

Editorial: 鈥�No more excuses over switch to clean energy鈥�

THE age of renewable energy is upon us. Within three years, the amount of electricity generated worldwide from wind, solar and hydro energy will exceed what is made using natural gas, according to the Agency.

鈥淲ithin three years the electricity generated from wind, solar and hydro will exceed that from gas鈥�

The IEA also predicts that green power will provide double the electricity of nuclear plants 鈥� and outstrip every other electricity source except coal 鈥� by 2016. If all goes well and current national energy plans come true, coal could be overtaken shortly after 2035.

The growth in renewables isn鈥檛 yet enough to stop dangerous climate change. Green power is on the rise, but so is our appetite for energy, so new coal and gas-fired power stations are in the pipeline.

But the good news is that renewables are the fastest growing power source. Already, they account for one-fifth of global power generation, and the IEA believes that will rise to 25 per cent by 2018. Between 2012 and 2018, renewable energy generation is predicted to increase by 40 per cent, with over a third of this growth occurring in China. Renewables are on the rise in most regions with only Russia lagging behind, says Adam Brown of the IEA in Paris, France.

鈥淥ver the last few years there鈥檚 been a big step forward,鈥� he says. 鈥淭he technologies are well-developed and costs have come down.鈥�

Globally, the biggest source of green electricity is hydropower, followed by onshore wind. Big dams like China鈥檚 Three Gorges have given hydropower a bad reputation 鈥� displacing human populations, wiping out wildlife and disrupting water flows. As a result, the World Bank stopped funding large-scale projects in the 1990s, but started again in the past decade. 鈥淭here are now well-developed procedures for managing the sustainability of dams,鈥� says Brown. A planned dam on the Congo river, for instance, will not flood any land: the river flows at such high volumes that a reservoir isn鈥檛 needed.

Why do hydropower and onshore wind dominate? Unlike solar and offshore wind, they can be as cheap as coal or gas 鈥� both are tried and tested technologies that have been fine-tuned to be efficient and cost-effective. The IEA expects almost 75 countries to use onshore wind by 2018. Even Texas, famous for its oil and gas, has embraced wind power: wind supplied 7.4 per cent of its electricity in 2012, .

Solar could catch up as costs rapidly fall. of the University of California, Berkeley, predicts a 70 per cent reduction in the cost of solar-generated electricity between now and 2020. Already, it is cheaper than electricity from diesel generators 鈥� popular in developing nations 鈥� thanks largely to cost savings from mass production.

The IEA says 2013 should be a decisive year for concentrating solar power, which uses mirrors to focus the sun鈥檚 rays, generating heat to power a turbine (see photo). Several big projects 鈥� such as a at Crescent Dunes in Nevada 鈥� are almost complete. 鈥淚f these projects get over the finishing line, that will lend credibility and bring costs down,鈥� says Brown.

To ease the transition to renewable energies 鈥� and ensure a reliable electricity supply 鈥� new power plants can combine renewables and fossil fuels. Biofuels are mixed in with coal in co-firing plants, cutting greenhouse gas emissions. The concentrating solar plant nearing completion at Ivanpah, California, its turbines on cloudy days. And General Electric is planning a power plant in Karaman, Turkey, that will combine . Big emissions cuts are cheap when renewables and gas are used in this hybrid mode, says Kammen ().

All the signs are good, but energy analysts warn that major changes in policy are still needed to avoid tipping over the 2 掳C threshold that constitutes dangerous global warming.

The elephant in the room is coal, which is cheaper than all other forms of energy and releases more greenhouse gases for every unit of energy generated. By 2018, it will still account for 40 per cent of global electricity generation.

The IEA has looked at national energy plans and estimates that if they are followed, renewables should catch up with coal shortly after 2035 (see graph). Even so, coal will still generate roughly one-third of our electricity supply. It can be cleaned up to some extent, either by capturing and storing the emissions, or by switching to clean-burning technologies like . But these solutions are far from economical.

What鈥檚 needed, say energy analysts, are assurances that investors can safely put their money into renewables and expect to make a bigger profit in the long-run than if they invested in fossil fuels.

鈥淭he best way is to agree a global price for carbon,鈥� says Will Straw of the Institute for Public Policy Research in London. This would make coal prohibitively expensive, and new gas-fired power plants less tempting.

Emissions trading schemes are one way to make pollution costly. Regional ones already exist in Europe, Australia, several US states, Canada, New Zealand and Kazakhstan. China, Brazil, Mexico and 10 other nations have plans for more. Small trading systems can be linked into regional ones, or even a global one.

The latest figures show that renewable electricity has made huge inroads without any global plan. If governments finally take decisive action, the future could be very low-carbon indeed (see editorial, 鈥�No more excuses over switch to clean energy鈥�).

This article appeared in print under the headline 鈥淥ur green future starts now鈥�