A survey by the Environmental Protection Agency based on consumption per year shows that global brands, including computer companies, topped the list in 2012.

Intel had the greatest use of renewable energy, with three trillion watt-hours of power: that's 3 terawatt-hours (3TWh), which represents 100% of its electricity requirements.

Microsoft came second with 1.936TWh, but still sources one fifth of its electricity from conventional sources.

Apple came 10th in the list, with 537.4GWh, or 85% of its requirements.

Three companies in the top ten generate more than their requirements: Whole Foods Market, a retailer of natural and organic foods with seven stores in the UK, comes fourth in the list and generates 107% of its power, or 800.3GWh,

Kohl's, a chain of department stores, generates 105% or 1.5TWh, while Staples generates 101% of its requirements, or 636GWh.

Walmart only generates 4% of its power from renewables, but has a target of generating all of it. Nevertheless it comes in fifth, because of its size, with 751.4GWh.

In sixth place is the US Department of Energy, setting an example with 14% of its power (698.5GWh); eighth comes Starbucks with 70% (592.5GWh), followed by aerospace company Lockheed Martin, which consumes 546.4GWh, or 30% of its requirements from renewables.

Looking at the whole top 50 companies, 16 of them receive 100% of their energy needs from renewable sources, and eight of them exceed the 100%.

Apple's data centres are now 100% fuelled by renewable energy, remarkable considering that it came under attack only a few years ago for using coal excessively.

Walmart's pledged this week to put solar power on at least 1,000 US rooftops by 2020. It will produce or buy 7 billion kilowatt hours (kWh) of renewable energy globally every year, a 600% increase over 2010 levels, but also reduce energy intensity per kWh by 20% from 2010 levels by switching all of its lighting to LEDs, employing building energy management systems and installing efficient HVAC and refrigeration systems.

This will save it more than £1bn a year on energy costs and reduce greenhouse gases to the equivalent of taking 1.5m cars off the road.

The EPA data also shows that 20 companies, organizations, and municipalities themselves generated on-site at least 6 million kWh in 2012, and, together, consumed more than 780 million kWh of green power.

In Britain, companies and organisations are increasingly seeing investment in renewable energy as a valuable business activity, whatever their core business is, because of the income it can generate and future price security.

Ikea, for example, the world's biggest furniture retailer, recently committed to doubling its renewable energy investments to $4bn by 2020, and achieving 100% of energy consumption from renewable sources for its stores as well as its supply chain. Significantly, it cited the principal reason as being "part of a drive to reduce costs as cash-strapped consumers become more price sensitive".

Other companies, such as sportswear maker Puma and PepsiCo, are following suit, as part of their competitive strategy to win customers.

All of these companies are helping to reduce costs of renewable energy. Prices for wind turbines have fallen 23% in the last three years, and the cost of solar panels by more than half in two years, according to Bloomberg New Energy Finance.

This is helping employment too. According to the Solar Foundation, solar power employs people in every American state, more than does coal mining, and more people work in solar power in Texas than in ranching these days.

The International Hydropower Association's report on last year shows that, globally, hydropower increased by 30 GW of installed capacity, and pumped storage added another 2-3 GW.

Global wind capacity also increased by 19% in 2012, with nearly 45 GW of new installations, a 10% increase on 2011, according to the Global Wind Energy Council (GWEC)'s Annual Market Update, although this is a slightly slower increase in growth than in the previous year.

National policies are helping to increase prospects for renewable energy as well.

On Wednesday, India's prime minister, Manmohan Singh, used his inaugural address to the 4th Clean Energy Ministerial, to announce that India will double the amount of renewable energy it can generate in the next four years to 55 GW.

"It is proposed to double the renewable energy capacity in our country from 25,000 MW in 2012 to 55,000 MW by the year 2017. This would include exploiting non-conventional energy sources such as solar, wind power and energy from biomass," Singh said.

He also announced a national target of increasing the efficiency of energy use to achieve a reduction of up to 25% in the energy intensity of India's GDP by 2020.

China has also improved its renewable energy policies, increasing its ambition and raising its deployment targets.

In Britain, wind energy generated more than 5 gigawatt-hours (GWh) of electricity consistently over a 48-hour period in March for the first time, enough to power more than 10% of the country's overall electricity needs, and the equivalent of nearly four out of every 10 homes. Also, a record 5.296 GW of wind was present on the grid at one point, measured as average generation over a half-hour period, according to Elexon, which tracks half-hour averages of generation.

Despite all this, progress in renewable energy is still not happening fast enough, according to the International Energy Agency (IEA).

In Tracking Clean Energy Progress 2013, the agency's input to the 4th Clean Energy Ministerial conference, which finished yesterday, it says that, despite some advances in renewable energy and developing world energy policies, the global energy supply is not getting cleaner. In fact, progress is “alarmingly slow”.

"Despite having the power to create policies and market conditions that advance clean energy technologies, governments are failing to do so at a pace commensurate with the scale of the decarbonization challenge," it says.

In other words, demand is exceeding the supply of renewable energy, with most of the remainder coming from coal.

Putting these two trends together, in the private and public sectors, it seems that the most far-sighted companies are leading the world's switch to renewable energy, while governments are lagging behind.

Story: David Thorpe, News Editor