The UK could be primarily powered by a secure and inexhaustible supply of renewable energy by 2030 without the need for new nuclear power plants, according to a report commissioned by WWF. Between 60% and 90% of the nation's electricity could come from wind, solar, tidal and other sustainable sources, with the rest supplied via an international supergrid and gas power stations.

"This report is inspiring, but also entirely realistic. It shows that a clean, renewable energy future really is within our grasp," said David Nussbaum, chief executive of WWF-UK. "Failure to commit to a high-renewables future would leave us facing the prospect of dangerous levels of climate change and high energy prices."

The soaring cost of energy bills has become a major political issue, with the prime minister, David Cameron, recently convening a meeting of industry energy leaders. The new report notes that meeting an existing 2020 renewable energy target will increase household bills by 4%, but that this could be more than offset by cuts in usage through better energy efficiency.

"Developing a low carbon and sustainable power sector in the UK is first and foremost a question of political will," concludes the report, which comes at a time when the Conservative party's commitment to be the "greenest government ever" is being seriously questioned.

The report states backing renewables would create hundreds of thousands of jobs and new economic growth. "Investing in clean energy offers us a means to tackle the two most crucial market failures that now confront the world: the financial crisis and climate change," said Nussbaum. "The only question that remains is, are we bold enough to take it?"

The report was welcomed by a host of businesses, including one the UK's "big six" energy suppliers, SSE. "It's a useful addition to the debate," said Keith MacLean, SSE's policy and research director. "Sufficient certainty that renewables will be a long term part of the energy system, well beyond the current 2020 cliff edge, is needed in order to allow the industry to mature and put renewables on a path of cost reduction that will steadily reduce and eliminate the need for support."

WWF's Positive Energy report differs from previous analyses by including a continuation of renewable energy building after 2020, as well as big increases in energy efficiency. The energy scenarios at the core of the report were developed by GL Garrad Hassan, the world's largest renewable energy consultancy and part of the GL Group, which also works in the oil and gas industries. In the highest renewables scenarios (90% of capacity), ambitious action on energy efficiency reduces the capital costs of renewables, gas and supergrid interconnectors from £216bn to £170bn. The report calls for a firm renewable target for 2030, to give long-term and stable financial support for the renewable industry.

The WWF report sets out a far more ambitious role for renewable electricity than the 45% predicted by the government's official advisers, the Committee on Climate Change, in its renewable energy review in May. But WWF points out that the build rates in its scenarios are actually lower than the government's own forecasts in its national renewable energy action plan and significantly below industry projections on realistic build rates. The difference is that in WWF's scenarios, rather than build rates falling rapidly after 2020, growth is maintained.

The electricity not generated from renewables in the report's scenarios comes instead from gas power. In the most ambitious 90% scenarios, the carbon emissions from those gas plants do not need to be captured and stored underground in order to meet the UK's climate change targets, but in the less ambitious 60% scenarios, about one-third of the gas plants would require carbon capture and storage (CCS) technology to be fitted. There are no coal plants of any sort in the scenarios, or nuclear plants.

The report warns of the danger in the less ambitious scenarios of being "locked-in" to high carbon emissions, because once unabated gas plants are built, operators will want to run them as much as possible to make a return. In the 60% scenarios, without significant supergrid interconnectors, the gas plants would run just 33% of the time.

The warning that a new "dash for gas" could lock in high carbon emissions is echoed in another report published on Tuesday, from MPs on the Commons select committee on energy and climate change. The MPs state the current proposals for electricity market reform put too much emphasis on building new gas plants to fill the gap left by the closure of about 19GW of nuclear, oil-fired and coal-fired plants by 2020, and not enough on decarbonising the power sector over the course of the 2020s in which gas without CCS will have "only a very limited role". The climate and energy secretary, Chris Huhne, told the Guardian last month that the government "will not consent so much gas plant so as to endanger our carbon dioxide goals".

The MPs' report also echoes WWF's call for more action on energy efficiency. "The government could be doing a lot more to reduce unnecessary energy wastage," said Tim Yeo MP, the Conservative chairman of the committee. "It needs to look at how it can use building regulations and energy efficiency standards for electrical appliances to cut waste and save cash on people's energy bills."

The committee's report additionally calls for much more gas storage capacity in the UK, to minimise the damage from supply interruptions or price spikes. The UK's current storage capacity is just 14 days' worth of gas, states the report, "a dangerously low level compared with France which has 87 days' worth of gas storage, Germany 69 and Italy 59."

Energy minister Charles Hendry said: "Energy security is right at the heart of the coalition's energy policy. We are reforming the electricity market to encourage investment in new power stations. We have also legislated for a mass roll-out of energy efficiency measures across Britain's housing stock through the green deal."