Energy from increasingly-competitive renewable sources such as wind and solar has quadrupled globally in just a decade, the United Nations said Thursday, but insatiable demand saw power sector emissions rise 10 per cent. This is more than triple the amount of the previous decade. The figure excludes large hydropower projects and is equivalent to 1.2 terawatts (TW) of new renewable energy capacity this decade. That's more than today's entire U.S. electricity generation units and half of the 2.4 TW of total power capacity installed over the same period.The increase stems from a fall in interest rates in major economies and a slump in costs, with the "levelised" cost of solar photovoltaics down 81%, onshore wind down 46% and offshore wind down 44% this decade.The levelised figure is the cost of generating a megawatt hour of electricity; the upfront capital and development cost; the cost of equity and debt finance and operating and maintenance fees.Worldwide investment in renewables since 2009 is on course to hit $2.6 trillion (2.35 trillion euros) by the end of the year, largely driven by "spectacular" falls in the price of solar panels, the UN's annual assessment of green energy trends said.The world's renewable capacity -- power generated from solar, wind, geothermal and biomass -- rose from 414 gigawatts in 2009 to 1650 gigawatts this year, and renewables now account for 12.9 per cent of all electricity generated on Earth.Solar accounted for the largest single share of the more than 2300 GW of additional power capacity installed globally in the past decade, outpacing fossil fuels such as coal and gas.The biggest investing country during the decade is set to be China, which committed $758 billion between 2010 and mid-2019. Over the same period, Europe invested $698 billion and the United States spent $356 billion, the report said.Yet despite the surge in carbon-free solar and wind, emissions from power have continued to rise, with the world belching out more manmade greenhouse gases in 2018 than any year on record.Inger Andersen, executive director of the UN Environment Programme, hailed Thursday what she termed a "decade of incredible growth in renewables"."This shows that the transition of the energy sector is on its way," Francoise d'Estais, head of the UNEP finance unit's Energy and Climate Branch, told AFP."It's still not rapid enough for the world to meet both climate and development goals."Authors of the report, compiled in conjunction with the Frankfurt School of Finance and Management and Bloomberg New Energy Finance (NEF), said the switch to renewables was largely driven by cost competitiveness.The price of energy generated by solar photovoltaics has fallen 81 per cent since 2009, while onshore wind energy is now 46 per cent cheaper than a decade ago."If you time travel back we would be astounded by what has happened since then," said Angus McCrone, chief editor of Bloomberg (NEF)."The image of renewables was that they were fairly expensive, dependant on subsidies, and a bit of a rich economy luxury in a sense.Certainly that was the argument from the fossil fuel side."Last year renewables saved the equivalent of two billion tonnes of carbon dioxide emissions, the report said.Yet overall emissions from energy continue to rise, imperilling the temperature goals laid out in the Paris climate deal as global demand shows no sign of abating."Counting for renewables growth is only half the story," Ulf Moslener, head of research at the Frankfurt School, told AFP."When I'm on a diet I can't just count the salads I'm eating but also the chocolate cakes. So it's a case of trying to substitute fossil fuels out of the market and I see that as quite a challenge."The report highlights 30 nations that have invested at least $1 billion in renewables in the past decade -- many of whom are also significant producers and users of fossil fuels.For example China, which produces around 29 per cent of manmade CO2, is far and away the biggest investor in renewables, ploughing in $760 billion since 2010.Without naming China specifically, McCrone said some nations had something of a "split personality" when it came to energy."They want to retain the market for the fossil fuels that they derive income from," he said."On the other hand they don't want to be left behind in the technological race and do nothing on renewables.""While this demonstrates huge and lasting progress, the pace must increase. Renewables are now firmly embedded in the power generation sector but only represent 26.3% of total electricity produced – 12.9% if we exclude large hydro," the report said."Fossil fuel subsidies, which run into the hundreds of billions of dollars each year, are slowing progress," it added.Around 529 GW of new coal plants have been added this decade, 487 GW of new wind capacity and 438 GW of new gas-fired power generation.Although more new capacity was added for solar than coal or gas, it does not directly translate into new power generation because solar is intermittent and dependent on sunlight.(Inputs from AFP and Reuters)