The Abbott government will appoint a “windfarm commissioner” to handle complaints about turbine noise and a new scientific committee to investigate, again, their alleged impacts on human health, in a late-night deal with anti-wind senators over amendments to renewable energy legislation.

A leaked draft letter from the environment minister, Greg Hunt, to the crossbench senators – obtained by Guardian Australia – details the promises the government has made to win the senators’ support for wood waste to be included as a source of renewable energy – a proposal opposed by Labor but which the government has insisted be included in the broad deal it struck with the ALP to reduce the renewable energy target.

The draft letter follows meetings on Wednesday between Liberal Democratic party senator David Leyonhjelm and the prime minister, Tony Abbott, and between Hunt and the eight senators who sit on the crossbench.

Hunt writes he has agreed “subject to the passage” of the government’s desired amendments to a long list of new regulation and monitoring of windfarms, including:

• Appointing a national windfarm commissioner to handle complaints from “concerned community residents about the operation of wind turbine facilities” and publish new sound monitoring data and information about the hours that turbines operate and the noise they generate.

• Appointing an “independent scientific committee” in consultation with members of an anti-wind Senate inquiry and “key industry and regulatory bodies”. The committee will “provide research and advice to the minister on the impact on the environment and human health of audible noise (including low frequency) and infrasound from windfarms”.

• Pledging the government will issue a statement that it “will respond actively and in good faith to the findings of the Senate select committee on wind turbines”. The committee is investigating claims about the impact of turbines on health.

• Writing to the Clean Energy Finance Corporation to ensure “significantly increased uptake of large-scale solar and energy efficiency”. Government policy is to abolish the Clean Energy Finance Corporation.

Asked about the leaked letter during Senate question time, the minister representing the minister for the environment, Senator Simon Birmingham, confirmed the government was “consulting crossbenchers to address concerns they have” but denied a deal had been done.

He said it was misleading to say a deal had been done because the letter was an unsigned draft.

But the crossbench senators said the letter represented a good offer from the government, and they were now negotiating to “strengthen some of the items relating to wind farms” before a deal was announced on Monday, when the renewable energy bill is expected to pass the senate.

Many of the crossbenchers pushing the anti-wind farm measures sit on a committee which on Thursday produced an interim report. Many of its recommendations are similar to the measures agreed to by Hunt in the leaked letter, but the committee also recommends that windfarms be charged a levy to fund the new scientific committee, and that they be denied government subsidies if they do not comply with the new guidelines.

Last week the prime minister said he found windfarms noisy and “visually awful” and disclosed that the government’s aim in the RET deal was to reduce the number of wind turbines as much as possible, given the makeup of the Senate.

Leyonhjelm, the Family First senator, Bob Day, and the independent senators John Madigan and Jacqui Lambie are all concerned about the growth of wind energy in Australia.

Facebook Twitter Pinterest Leyonhjelm swore at a group of satirical protesters at an inquiry into wind energy last week. Link to video

The government struck the deal implementing the reduced renewable energy target of 33,000 gigawatt hours with the Labor party and does not need the crossbench votes to get it through the Senate. Leyonhjelm told the Senate on Wednesday he would vote against it.

But at the last minute the government also included the burning of native forest wood waste in the activities eligible under the RET. Labor has said it will try to amend the legislation in the Senate to remove wood waste burning and the government needs the crossbench votes to defeat this amendment.

Leyonhjelm, Madigan and Day have been using their votes on the amendment to leverage concessions from the government to constrain the growth of the wind industry.

In an interview with the Sydney radio announcer Alan Jones, Abbott said: “I do take your point about the potential health impact of these things … when I’ve been up close to these windfarms not only are they visually awful but they make a lot of noise.

“What we did recently in the Senate was to reduce, Alan, capital R-E-D-U-C-E, the number of these things that we are going to get in the future … I frankly would have likely to have reduced the number a lot more but we got the best deal we could out of the Senate and if we hadn’t had a deal, Alan, we would have been stuck with even more of these things …

“What we are managing to do through this admittedly imperfect deal with the Senate is to reduce the growth rate of this particular sector as much as the current Senate would allow us to do.”

In a report released in February the National Health and Medical Research Council concluded that “there is currently no consistent evidence that windfarms cause adverse health effects in humans”.

The council is is offering grants worth $500,000 for five years for more research on windfarms and human health.

A Sydney University review of 25 studies into the possible health effects of wind turbines found none had produced evidence they were detrimental to human health and in 2014 the Australian Medical Association issued a statement saying the available evidence did not support the idea that windfarm noise harmed humans.