Firming capacity and the aero-derivative gas turbine

We are seeing no end to the construction of solar farms on the NEM, additionally rooftop solar continues to penetrate at a great rate of knots. This is leading to the duck curve becoming more pronounced, particularly in Queensland.

I think most of us in the industry would like to see this rate of growth of renewable energy continue and to see our reliance on higher CO2 emission technologies drop.

If we are to displace older coal plant with a low carbon power supply; and this supply is also dispatchable over many hours (or indefinitely), then it is clear that additional firming capacity is required on the NEM. This firming capacity is required so that the high rates of change in net demand can be dealt with (as we climb the duck’s neck each evening) and so that we can cover peak demand in the evening after the sun has set (as we pass over the duck’s head).

Batteries and pumped storage hydro certainly have a place in providing firming capacity and will play a big role in our future. Currently both technologies struggle with Capex, Lithium Ion batteries struggle with degradation and depth of discharge and, there are limited opportunities for pumped storage hydro without adversely impacting land use and habitat (not to say that these issues cannot be overcome).

A less capital intensive option is the aero-derivative gas turbine.

The aero-derivatives are fast start (in the order of seven to ten minutes) and fast ramp (50% per minute), meaning that they are highly responsive. These fast response characteristics are well suited to the extreme rates of change that occur (and will become more extreme) as the sun sets and the evening peak consumption period commences.

With a small amount of battery storage, you are able to modulate net output between zero and 200% output in 100s of milliseconds (which might be handy in a world of five minute settlements). To achieve this, you keep your gas turbine on base load and modulate the charge/discharge cycle of the batteries to match prices driving up and down (if you are expecting prices to modulate from zero to VOLL every five minutes). The storage also allows you immediate dispatch of 100% of capacity while the gas turbine starts. I can see this having value when five minute settlements are introduced into Australia.

The aero-derivative is very efficient (ISO 40-44%) and therefore low carbon intensity (in the order of 0.5 tonne per MWhr on typical Australian east coast natural gas). When working in concert with a solar farm, you end up with the net average carbon intensity dropping substantially for the combined product (0.167 tonnes per MWhr for eight hours of solar combined with four hours of gas turbine). While this is not the (almost) perfect 0.000 that you might get with solar and pumped storage or solar and batteries, it is certainly an improvement on base load coal (in terms of carbon intensity) and not a bad economic outcome in terms of Capex dollars per tonne of CO2 saved.

Arche Energy is highly experienced in the development of aero-derivative gas turbine projects and stands ready to assist on your project or to find firming capacity for your portfolio.

Arche Energy has undertaken an extensive review of the bulk of the NEM and can very quickly identify sites in most NEM Zones suitable for development into a gas turbine or hybrid gas turbine/battery storage based power plant. Arche Energy is also working on development phase projects that might suit your portfolio or corporate objectives.

Please contact me for more detail.

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