A second public inquiry into the proposed Den Brook wind farm gets under way on Thursday.

It is understood the outcome could affect the future of wind farms across the UK.

Campaigners are confident of preventing Renewable Energy Systems (RES) from building nine 125m wind turbines between Bow, Spreyton and North Tawton.

The Den Brook Judicial Review Group (DBJRG) is still £15,000 short of the estimated £50,000 cost of fighting the case.

One of the group's directors, Mike Hulme, 60, whose home is 1,100m from the site of the nearest proposed turbine, said costs were increasing because more work than anticipated was having to be done with solicitors and barristers.

He said: "It's not easy raising money in the current economic climate and we've been on this so long. The group has 600 to 700 financial supporters but we raised the best part of £50,000 to go to the High Court last year.

"We've had lots of donations but they're much smaller than in the past. I can't knock what we've had, but the tail isn't keeping up with the head. I don't know how we're going to deal with it."

RES first applied for planning permission in 2005. Permission was granted in 2006, but the Secretary of State quashed this in 2008 following legal challenges put forward by the DBJRG. Both sides are reconvening before inspector Andrew Pykett on Thursday for a second inquiry.

Despite the lack of funds at the moment, the DBJRG will have legal representation for the duration of the inquiry.

"It's a major case and it could be of substantial worth to the legal people if we're successful," said Mr Hulme. "It's going to have implications nationally."

The South Molton wind farm inquiry has been adjourned. Mr Hulme said it was useful as a "dry run" for the Den Brook inquiry. He said: "Our noise expert was there, as well as the RES noise expert and solicitor who were both acting for a different company."

The crux of the campaigners' case is that data supplied by RES shows the company has significantly underestimated the effect of atmospheric conditions on the levels of noise likely to be produced. The group is also making submissions on the landscape.

Mr Hulme said: "Wind turbines are being built so high, the blades are sweeping through different layers of air. The swooshing turns to a whoomphing or thumping."

He experienced this when he stayed near a wind farm in Lincolnshire, at Deeping St Nicholas, for three days.

He said: "There was a whoomph every second to second-and-a-half for a couple of hours at a time. It came and went with different wind directions and speeds. When it goes on day in, day out, it's like Chinese water torture. The family I was staying with eventually decided to abandon their home because it was horrendous."

Mr Hulme said he had nothing against the principle of wind turbines but if the developers could not find a way to mitigate the noise the proposals were unacceptable.

He was feeling very confident about the inquiry. He said: "I think we've got an extremely good case and the best team available working for us."

Rachel Ruffle, of RES, said: "The evidence RES is presenting at the inquiry reinforces what we have always said about the project - that it is a low-impact, well-sited, sensitively designed wind farm that should be allowed to go ahead in order to meet important renewable energy targets.

"Our latest noise analysis, carried out for us by independent noise experts, reconfirms that the wind farm will be within noise limits and will not, therefore, cause a noise nuisance to local residents."

She added that numerous companies in the local area had contacted RES hoping to tender for the construction work.

The inquiry starts at 10am at Okehampton Community College. It is expected to last eight days.