Baw Baw Pumped Hydro Energy Storage 1

(RENEW 153)

The growing need for deep and medium storage*

A bit over two years ago, this blog published an article suggesting a large-scale Pumped Hydro Energy Storage (PHES) in Gippsland could smooth the transition out of brown coal. This post, and several to follow**, offer some further insights on the need, potential configuration, and context of environmental impacts, of a Baw Baw PHES scheme.

In 2018 the Australian Energy Market Operator implemented a long-term blueprint for ensuring the ongoing performance, reliability, and least-cost transformation of the east-coast grid: the Integrated System Plan (ISP). The latest revision, released in July, considers five future scenarios: ranging from ‘slow change’ (with government intervention to extend the life of existing coal plants); to ‘step change’, where rapid action is taken to reduce emissions to meet and exceed our Paris climate goals. To anyone interested in Australia’s energy system, and emission reduction pathways, this document is an essential read.

The ISP makes it clear that a key requirement across scenarios will be an increase in dispatchable generation. This is needed to complement the large volume (over 26 Gigawatts) of low-cost, but variable, renewable energy projects forecast to come online in the next two decades, replacing the nation’s ageing fleet of coal generators. Between 6 and 19 Gigawatts (a billion watts) of such capacity will, depending on the scenario, be required over the next two decades, and is expected to be either gas turbine, lithium battery, or PHES technology. For context, Australia’s largest gas turbine facility is the 0.6 GW, four-unit Colongra station; the massive Snowy 2.0 expansion is 2 GW; and what was – until recently – the world’s largest battery in South Australia is 0.15 GW. The scale of new capacity required is, by any measure, enormous.

An energy storage facility is classed as either shallow or deep, determined by the length of time it can operate at full output before its energy is drained. Less than two hours is considered ‘shallow’: useful for bridging short ‘peak’ periods each day, like when solar drops off and demand peaks after sunset. 24 hours or more is ‘deep storage’, which can operate across seasons. It may build up charge, for instance, in spring when demand is low and wind and solar output high (see image above), and then discharge at the height of summer (or depth of winter) when power demand soars. ‘Medium’ storage sits between these two – typically between 4 and 12 hours of charge. As the proportion of variable renewable capacity increases, the greater the need first for medium, then deep, large-scale storage to meet demand. Despite advances in battery technology, and their fast-response, grid-stabilisation capabilities, the economics and practicalities of ‘deep storage’ batteries are still considered distant.

A Baw Baw PHES would not be an ‘alternative’ to Snowy 2.0: it, and a pipeline of other storage and transmission projects, will be needed to accelerate the transition from a fossil-powered grid. In the next post, we look at ways the Baw Baw scheme can be engineered and staged to provide deep (and ‘medium’) storage – as well as an insurance policy for the grid – over the coming decades.

* Our guest contributor is a Gippsland-bred engineer, working in the power industry

**To follow on over the next month or so are (2) further engineering insights and refinements (3) environmental impacts and (4) how to progress