A huge expansion of renewable energy will be launched by the government next week, when it sets out its plans for meeting its commitments to cut carbon dioxide emissions.

The plans have raised concerns about their cost, estimated at at least £100bn ($162bn), which will push up energy bills, hitting poor and vulnerable consumers.

Proposals have also been criticised by some companies and campaign groups as insufficiently radical.

Ed Miliband, energy secretary, will on Wednesday set out a package designed to show how the government will meet its self-imposed target of cutting carbon emissions by 34 per cent by 2020, and its commitment to the European Union that 15 per cent of the country’s energy will come from renewable sources by the same year.

The principal measures will include an extension of the renewables obligation, the subsidy scheme for renewable electricity, and new “feed-in tariffs” for small domestic and commercial generators to sell their electricity to the grid.

The government is likely to trim slightly its objective for renewable electricity – mostly wind power – as a proportion of total generation, from a previously suggested 32 per cent to 29 per cent. However, even that figure represents a huge increase on today’s proportion of about 5 per cent.

There will also have to be a steep increase in the proportion of residential and industrial heating from renewable sources such as waste, from 1 per cent today to about 12 per cent. The government plans to consult on a new financial incentive to support that.

Another initiative also being evaluated is a new scheme to provide home insulation in low-income communities, and pilot projects are expected to be launched next week.

However, the impact on bills of the huge cost of the investment needed by the energy industry is causing growing concern. Meeting the renewables target alone is expected to cost £100bn, with at least another £100bn needed in the rest of the energy industry.

To alleviate the effect of paying for that investment on the bills paid by vulnerable people, officials have been discussing a new statutory social tariff for pensioners on lower incomes claiming the pension credit. They would be entitled to lower bills, paid for by the companies charging more to other customers.

The government will also next week set out its low-carbon industrial strategy and plans for cutting the emissions from transport. However, outlines of the plans that have emerged in recent days seemed insufficiently far-reaching to some, both in the energy industry and in campaign groups.

Dieter Helm, an energy expert at New College Oxford, said the enormous investment needed in renewables would have been hard to finance even when financial markets were strong, and would be even more difficult following the credit crunch.

The returns to investors would need to come from the public through higher energy bills. “The question is: how is the government going to persuade the electorate to pay for it?” he said. “Because ultimately it is the voters that will be paying.”