The NI Renewables Obligation (NIRO) scheme was robustly defended by senior civil servants at Stormont on Wednesday.

It follows last month’s report from the NI audit office which found that financial returns from anaerobic digesters (AD) and small-scale wind turbines could be higher than initially projected.

“For a scheme as complex and far-reaching as NIRO, which ran for 12 years and accredited 24,000 generators, it is natural that any review would leave us with recommendations to follow up on,” said Thomas Byrne from the Department for the Economy (DfE).

When I look back at the decisions made, it followed the evidence

The department is currently conducting a review into the financial returns from NIRO in response to the audit office report. But a repeat of the Renewable Heat Incentive (RHI) debacle, where the scheme was unexpectedly changed mid-way through, seems unlikely.

DfE officials insist that the costs associated with renewable electricity technologies and the returns from NIRO were always kept under regular review. “When I look back at the decisions made, it followed the evidence,” Byrne said.

It means we have a greater opportunity here because the use of AD deals with the waste and is part of the solution

The audit office report queried why there are 3.5 times more AD plants per square kilometre in NI compared to Britain, but again this was defended by DfE officials.

“It is not really a surprise. The number of ruminants, cattle mainly, is 23 per square kilometre in NI and that compares to 9 per square kilometre in England,” said Richard Rodgers.

“It means we have a greater opportunity here because the use of AD deals with the waste and is part of the solution,” the DfE official added.

The key point raised throughout the briefing with MLAs was that NIRO was essential for NI to exceed the target of having 40% its electricity coming from renewable sources by 2020. “We are confident that it (NIRO) is value for money,” Rodgers said.