Realising the Economic Value of Renewable Energy from Biosolids

Biosolids management poses a range of financial, regulatory, environmental and social challenges for wastewater utilities. However, alternative biosolids management approaches can offer opportunities to derive greater environmental and economic value from biosolids, improve resilience and enable a more circular economy through co-treatment of organic waste. Hunter Water, AECOM and the Institute for Sustainable Futures (ISF) have assessed a range of centralised biosolids and co-treatment (biosolids and organic waste) options involving energy recovery as an alternative to the current biosolids management approach to an alternative centralised approach. Four scenarios were constructed to examine the resilience of various investment pathways under a range of plausible futures. The resilience of each pathway to a range of market and regulatory shocks, such as the banning of land application of biosolids and changes to regulation, was also explored. A centralised anaerobic digestion (AD) facility with energy recovery is more cost effective than Hunter Water’s current biosolids management approach. It will also improve resilience to future market and regulatory shocks and reduce Hunter Water’s carbon footprint by up to 10%. Thermal treatment offers greater resilience to potential regulatory and market shocks than both the current biosolids management approach and AD options. However, thermal treatment options have higher life cycle cost and a relatively immature regulatory approval pathway. The financial and economic benefits of co-treatment are countered by new commercial and financial risks. Co-treatment is not critical to the business case for centralised biosolids treatment and energy recovery at Hunter Water.