Financial support for anaerobic digestion (AD) plants in Northern Ireland could be higher than necessary, according to a new report.

The investigation into renewable electricity generation by the Northern Ireland Audit Office has raised questions about the calculations used for designing the incentive scheme for AD plants.

“The modelling used by the former Department for Enterprise, Trade and Investment to set the level of support for generating stations using biogas could be providing higher levels of financial support than necessary to investors in this technology,” the audit office states.

The Northern Ireland Renewables Obligations (NIRO) is the incentive scheme for renewable electricity generation in Northern Ireland.

The audit office report found “strategic shortcomings” in the design of NIRO, with concerns raised about small-scale wind turbines, as well as AD plants.

When compared to a similar scheme in Britain, the report identified a “higher level of financial support” was available for small-scale wind energy in Northern Ireland.

“The potential rate of return could be in excess of 20%, with a payback period [on the original investment] of less than four years,” according to the audit office.

The NIRO is a market-based scheme, where payments for renewable energy generation come from electricity suppliers, which means it is ultimately funded by consumers’ electricity bills.

Read more in this week’s Northern Ireland edition of the Irish Farmers Journal.