Renewable energy is in greater demand than ever before, and with wind and solar power fully established, there is a race on to see which countries are making the most of their hydro and marine power potential.

Just two percent of the world's coastal waters have wave power densities that are great enough for extracting wave energy. To create hydro, a hilly landscape and an abundance of water ways and rivers is critical. Both these facts mean that not every country is able to produce marine and hydro power, so this is not a race every country can enter - but there are five in particular that hold excellent potential.

Australia - and its vast coastline

"Just two percent of the world's coastal waters have wave power densities that are great enough for extracting wave energy."

Australia has 34,218 kilometres (21,262 m) of coastline (excluding all offshore islands) and is an area identified with some of the world's best marine power potential across its southern coastline.

For example, the total wave energy crossing the 25 metre depth isobath between Geraldton and the southern tip of Tasmania is more than 1300 TWh/year, estimated at about five times the total electricity requirements of Australia. It also has many rivers and creeks that can, and have, been used to harness hydroelectricity power. One drawback however is the extremely hot temperatures, which can result in high evaporation rates.

Currently hydroelectricity accounts for 6.5-7% of Australian electricity generation. Hydroelectric power has been generated in Australia for more than a century in various large and small projects, but perhaps the largest and most significant is the Snowy Mountains Scheme. The scheme was set up between 1949 and 1974 and consists of sixteen major dams, seven power stations, a pumping station and 225 kilometres of tunnels, pipelines and aqueducts.

While Australia is harnessing hydro power without much hesitation, their tidal and wave power industry still hasn't taken flight, with only two tidal and wave facilities currently set up. Although according to Clean Energy Australia, a not for profit industry association, 2011 report found that in that year, more than 15 companies had been actively investigating wave and tidal energy projects in Australia. Wave resources are mostly being explored along the southern and western coastlines, while the northern coastline is the focus for those exploring tidal resources.

North America - already exploiting hydro power

Rich in coastal waters and rivers, North America has huge hydro and marine power potential, which it is slowly developing. Hydro power already provides nearly seven percent of the nation's electricity, and it holds tremendous potential for expansion. Last year alone, the US awarded grants to around 14 different hydro power projects around the country.

A report by the US Department of Energy revealed that wave and other water power resources across the US could potentially provide 15% of the nation's electricity by 2030, with areas such as Hawaii being identified as having enough energy to generate more than 80 terawatt hours of electricity a year if developed to their maximum potential. Alaska was also identified as having a high potential for wave energy developments, along with some areas of the East Coast, which have strong tides that could be tapped into to produce energy.

One project currently being laid out is the Roosevelt Island Tidal Energy project, where 30 turbines are being installed along the strait that connects the Long Island Sound with the Atlantic Ocean in the New York Harbor. The turbines are scheduled to be fully installed by 2015 and will use the flow of the river and tides to generate 1,050 kilowatts of electricity - enough to power 9,500 New York homes.

They are also developing a fish friendly turbine expected to change the hydro industry in the USA and with excellent potential for exportation. Scientists and engineers at the Electric Power Research Institute (EPRI) have designed a new turbine which reduces fish passage injury and mortality, while effectively maintaining power production.

South Korea - riding on its tidal currents

Pike Research, which provides rigorous examinations of emerging clean-tech markets, estimates South Korea will be one of the top countries producing tidal stream energy in the world.

"In 2010 South Korea commissioned 'the four rivers project' which aimed to regulate four rivers and provide the region with clean energy."

This is likely due to its west and southern coasts being known for high tides and strong tidal currents.

In a 2006 report by the Coastal Engineering Research Department, wave energy resources along the South Korean coast were estimated at 650MW, and the country has been developing technology since 2000. In 2008 South Korea embarked on, what was at the time, the world's largest tidal power project along the Wando Hoenggan Water Way off the South Korean coast, which is expected to be up and running by 2015.

Hydro power has already taken off in South Korea considerably, with 40% of the country's energy being generated by it. Since 2001, several large hydro and nuclear plants in South Korea have been run by Korea Hydro & Nuclear Power (KHNP), which is a subsidy of the Korea Electric Power Corporation. The country is also taking its expertise in the field abroad, with South Korean companies said to be in the running for two major hydroelectric construction contracts in Georgia, the Korea Herald Newspaper reported. The country has also pledged its fullest support to the development of hydro power in Sri Lanka.

In 2010 South Korea commissioned 'the four rivers project' which aimed to regulate four major rivers and provide the region with clean energy. Mavel, the company in charge of the projects, announced in February that it had successfully commissioned two of the projects, and would do so with the others by the end of 2012.

The UK - taking small but important steps

Along with South Korea, the UK is being heralded as one of the leaders in wave and tidal power technology, with some of the best - and unique - testing facilities in the world.

But despite this there has been added pressure on the government to invest more into the industry so it becomes a front runner and doesn't lag behind. Currently the UK industry is taking small but extremely significant steps towards harnessing wave and tidal power, thanks to developments such as the Searaser - a cost effective underwater pump which creates power from the swells and tides of the ocean - and it currently possesses seven out of the eight large-scale prototypes deployed anywhere in the world.

According to The Carbon Trust, which provides support to business trying to cut carbon emissions in the UK, marine power could create 10,000 jobs by 2020. By 2050 the global market could be worth £340bn, with the UK claiming about one-fifth of the business.

According to the Department for Energy and Climate Change, the UK currently generates about 1.3% of its electricity from hydro power. Most of this is generated from large scale schemes in the Scottish Highlands. Recent studies estimate there is a remaining viable hydro potential of 850-1,550MW in the UK. This represents approximately 1-2 percent of current UK generating capacity.

Most of this would be found in small scale hydro plants dotted around the country. Currently some old water mills are being refurbished and brought back into the energy supply network. In 2010, the environment agency mapped the UK for hydro power potential and identified 26,000 locations where turbines could be installed to generate power from the water, but half the sites are environmentally sensitive so would need special engineering to avoid killing fish.

China - the Asian giant goes full steam ahead

"China already utilises the advantages of hydro power - at the end of 2012 its hydro power capacity was 213.4 gigawatts - the highest in the world."

With one of largest populations in the world China needs a lot of energy. While most of its energy comes from non-renewable sources, the country is aiming to have 20% of its energy come from renewable sources by 2020.

With 18,000km of coastline and 6,500 islands, China has great tidal and wave power potential. One project it is working on is Blue Energy, a 120km tidal energy generating bridge across the Bohai Strait.

It is estimated to be able to generate more than 70,000MW of power a year. Also in the Zhejiang area, in Taizhou City, there are an estimated thousand megawatts of energy up for grabs, along the 630 kilometres of coastline.

China already utilises the advantages of hydro power - at the end of 2012 its hydro power capacity was 213.4 gigawatts - the highest in the world. However, China is still planning on going full steam ahead with hydro power projects, although some of these are courting controversy.

For example, there has been much scepticism and apprehension around China's proposal to up-scale and build further dams in the Yangtze River, which is already the world's largest power station in terms of installed capacity.

Many believe the project is too large and there are too many damaging sociological and environmental factors. There are also many other hydro power projects planned by the Chinese Government, who believe this is the way to go in regards to meeting their reduced emissions targets and aiming for eight ten-gigawatt hydro power bases by 2015. These will be based along the Jinsha River, Yalong River, Dadu River, Lancang River, Nujiang River, the Yellow River, the Brahmaputra River and others besides.