Sustainable Energy

Are these the greenest countries in the world?

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Energy from the wind, sunlight, tides and geothermal heat is fast becoming an increasingly major part of the world's energy mix -- as can be seen in the vast range of renewable energy projects taking place across the world, from China to the U.S.

CNBC's "Sustainable Energy" takes a look at a quarterly index from professional services firm EY, which ranks 40 countries "on the attractiveness of their renewable energy investment and deployment opportunities, based on a number of macro, energy market and technology-specific indicators."

Read on as we profile the top 10.

(10) Netherlands

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The Netherlands moved up two places to tenth in EY's index. From December 2015, the next four years should see 700 megawatts of energy coming from offshore wind farms each year.

This year also saw a court ruling ordering the Dutch government "to tighten its greenhouse gas emissions rules." EY commented that this was the first time that a government had been "legally ordered to do more to address climate change."

The Dutch government has said it is committed to boosting wind and solar energy. By 2023 it aims to generate at least 16 percent of energy from renewable sources, with a "fully sustainable energy supply by 2050."

(9) Chile

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Chile climbed to ninth place in the index, with EY commenting that the success of renewable projects had helped to drive down energy prices in the country.

This came about after what EY described as a "landmark decision" to open up the country's energy auctions to renewables such as solar, enabling greater competition.

In September 2015, Acciona Energy announced plans to build Latin America's largest photovoltaic power plant in Chile. The $343 million project will be located in the Atacama desert and have a capacity of around 0.25 gigawatts.

(8) Brazil

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Along with Paraguay, Brazil is home to the vast—and controversial—Itaipu dam, which generated 87.8 million megawatt hours in 2014 and provides the country with roughly 17 percent of its energy needs, as well as 75 percent of Paraguay's energy.

Overall, the country's thirst for renewables is increasing.

Last year saw $7.6 billion in renewable investments, a 93 percent increase on the previous year, according to the Frankfurt School–UNEP Collaborating Centre for Climate and Sustainable Energy Finance.

"To say that Brazil's investment climate is currently challenging would be an understatement," EY said, but also highlighted the country's plan to install 24 gigawatts of wind capacity and 7 gigawatts of solar by 2024.

(7) France

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EY praised France for its adoption of a law committing itself to cut the proportion of nuclear energy from 75 percent to 50 percent and generate 40 percent of electricity from renewable sources by 2030.

At the end of 2014, France had 9,285 megawatts of installed wind power, according to the European Wind Energy Association, while its solar capacity was 5.6 gigawatts, according to Reuters.

(6) Canada

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Sixth in EY's index, renewables provide roughly 16.9 percent of Canada's energy supply. The country is the world's third-largest producer of hydroelectricity and the Canadian government says that "moving water" is its most important renewable source.

However, efforts to diversify away from hydro are underway and the government says that wind and solar photovoltaic are the country's fastest growing sources of electricity.

According to EY, the province of Ontario, which is home to both Toronto and the national capital of Ottawa, will need to find an extra gigawatt of capacity "to reach its target of 10.7 gigawatt non-hydro renewables by 2021."

(5) Japan

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August saw fifth-placed Japan restart its first nuclear reactor since the Fukishima disaster of 2011.

The country has set itself impressive targets when it comes to clean energy. It announced this summer that it aimed to cut greenhouse gas emissions by 26 percent by 2030, compared to levels in 2013, according to Reuters.

(4) Germany

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Despite falling in the index from third to fourth place , EY said that Germany "remains the jewel in Europe's renewable energy crown, enjoying a relatively high degree of government support and policy stability."

EY added that Germany – Europe's largest economy – also has the highest solar capacity on the planet, with 38.9 gigawatts installed at the end of June 2015.

Germany has set itself ambitious targets for renewable energy. The country's Federal Ministry for Economic Affairs and Energy says that it wants to produce between 40 and 45 percent of electricity from renewables by 2025, with that number rising to between 55 and 60 percent by 2035.

(3) India

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One of the world's fastest-growing economies, third-placed India has set itself incredibly ambitious renewable energy targets.

In June 2015, the Indian government formally announced its plan to have 100 gigawatts of solar power capacity installed by 2022.

(2) China

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Ranked second in the index, China is currently embarking on a huge renewables push, and EY noted that the country's five-year outlook for wind and solar installations was "still double that of the U.S., reflecting the magnitude of the investment and deployment opportunities that are being driven by the fundamentals of surging energy demand and an environmental imperative."

China saw $83.3 billion of renewable energy investments in 2014, a 39 percent increase on 2013, according to the Frankfurt School–UNEP Collaborating Centre for Climate and Sustainable Energy Finance.

(1) United States

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The U.S. came top of the index, with EY praising President Barack Obama's Clean Power Plan, which it said, "Represents a much-needed long-term national framework that could accelerate the shift to a low-carbon economy."

Announced in August, the plan has a target of reducing CO2 emissions by 32 percent by 2030 compared with 2005. In addition, the White House says that renewable energy generation will increase by 30 percent by 2030 if the plan is fully implemented.

In 2014, preliminary data showed that renewables made up roughly 10 percent of U.S. energy consumption, according to the Energy Information Administration.