Watercare Services Ltd is a significant user of electricity from its water and wastewater treatment processes consuming 165 GWh in 2016/17. Of this, 30% is currently generated from biogas (cogeneration) and hydro leaving some 115 GWh supplied from the national grid. This represents a significant operational cost and provides opportunities for Watercare to explore alternative energy sources including enhanced cogeneration, solar PV and battery storage. Benefits are reduced costs to serve our customers, improved system resiliency and wider environmental benefits for New Zealand.
This paper highlights the challenges of reducing operational energy costs at a large water utility and the exciting possibilities presented by ever-more affordable distributed electricity generation technologies such as solar PV and battery storage, as well as next-level wastewater treatment technologies that optimise the production and use of biogas.
Starting with a new Energy Policy in 2016, several initiatives are now underway to improve energy conservation and investigate the financial benefits of self-generation, in particular photovoltaic solar panels. Starting with several pilot projects to confirm the real-world benefits including reduced electricity costs, the initiative will create new revenue streams from the export of surplus solar electricity back to the grid and pairing with battery storage.
Although in its infancy, battery storage compliments green energy technologies such as solar, hydro and biogas by storing the generated power and controlling the release of that energy. This can be optimized to maximise revenue by exporting to the grid when tariffs are high, reduce imported electricity costs by offsetting demand and avoiding high tariff peak periods, and possibly support wider community electricity infrastructure.
Water utilities require security of supply to ensure pumping and treatment processes continue during power outages. Battery storage technologies can provide this security in lieu of using traditional diesel generators that can be operationally complex. Security of supply is also a shared common interest with electricity network companies in areas where there are known power supply issues and population growth pressures. Partnerships are being formed where there is a shared interest to jointly fund, co-locate, or prioritise use of the battery storage solution by the water utility.
There is significant potential for large electricity users such as water utilities to become more energy independent using green energy and realise a sea-change in approach where electricity supply is not simply seen as an outsourced service, but becomes a fundamental part of the business that can be channelled to drive efficiency and innovation.