Mercury’s pioneering direct grid-connected battery: it’s large and in-charge

24 September 2018

During the recent two-day EMANZ Conference that I attended in Auckland with our Energy Manager, Tânia Coelho, I was struck by the surge of genuine enthusiasm for and commitment to renewable energy from the diverse group of Energy Managers and others who attended.

In this regard, our country is in the fortunate position that 85% of our electricity supply already comes from renewable energy, mainly hydro-electricity, geothermal and wind-generation based.

Successive National and Labour Coalition Governments have made a strong and binding commitment to New Zealand meeting its global carbon emission reduction obligations.

To achieve these commitments in practice, New Zealand will need a sustained and integrated programme, to utilise rapidly evolving technology in this area.

The following guest post by James Flexman, Wholesale Markets Manager, Mercury highlights some of the excellent work in the inter-related areas of solar power and battery storage, that their company is championing.

Innovative Battery Technology Has Potential to Disrupt Fundamental Aspect of Electricity Market

The crazy thing about the electricity market, the thing that sets it apart from almost all other markets, is its immediacy. Electrons are the ultimate NOW product. They’re right here, right now, turn on the switch, see the light.

New Zealand’s sophisticated spot market and all its intricacies have been developed to work with electricity’s time-bound quirk of physics and deliver reliable, affordable and mostly renewable electricity to Kiwi homes and businesses.

But now this non-negotiable is being challenged. There’s a ‘disruptive technology’ on the scene that, like a kind of Timelord, has the potential to substantially diminish the impact of time and timing on the generation, dispatch and ultimate use of electricity. We’re talking about the exciting new opportunity created by super-batteries that can charge up with electricity from the grid and store it, before being re-dispatched into the electricity market.

Grid-Connected Battery Research & Development

Last week Mercury launched its own 1MW/2MWh battery storage facility at our R&D centre in South Auckland. For context 2MWh of electricity could power 400 homes for a winter evening peak for 2 hours. On its own, it’s not going to change the world and it’s also definitely not for the short-term gain. The rate of return based on trading 2MWh of electricity in and out of the national grid means it would take many years to break even on the $3 million investment.

Being directly connected to the grid, and able to send energy into the market like a little 1MW power station makes this battery a Kiwi first. And there’s potential for much more.

So what are we expecting in the medium to long-term from this pilot?

The clue is in where the battery has been installed – in Mercury’s R&D Centre in South Auckland. For us, it’s all about the ‘R’ part of ‘R&D centre’: Research. And at a time when the Government is calling for greater investment in R&D in this country, I’d like to do a quick shout-out celebrating the constant ongoing investment in R&D undertaken by Kiwi businesses every day of the week.

The battery is a pilot, a toe in the water, part of the New Zealand electricity market’s ongoing exploration of battery storage as the technology evolves, to work out what part batteries will play in the energy generation eco-system of this country. We believe there’s potential here. Reflecting on the first generation in New Zealand (for power, not gold processing) at Reefton, it was a 20kW generator – and look what hydro generation has grown to and its role in our economy now.

Battery Pilot a Milestone for Innovation

And it’s a true innovation. Mercury is the first company in New Zealand to install a battery system that is directly connected to Transpower’s high voltage national grid and to use the battery to participate in both the energy and reserves markets. Others have explored other ways that battery storage could interact with our current energy landscape – Counties Power together with Genesis, Vector and Alpine Energy have all commissioned batteries that can participate in the energy market, but these are also used to manage local networks better.

Being directly connected to the grid, and able to send energy into the market like a little 1MW power station makes this battery a Kiwi first. And there’s potential for much more. The storage facility is on the site of Mercury’s mothballed thermal power station next door to Transpower’s Southdown switchyard which is capable of moving over 100MW in and out of the grid.

However, despite the facility being able to accommodate battery storage of this size (similar to the much publicised South Australian battery project that Tesla committed to (and did) build within 100 days), trading at this scale will only start once the R (Research) has turned to D (Development). But once this happens, (when battery technologies develop further and costs of large-scale batteries drop), the lessons we have learnt from our investment in 2018 will give us a fast start to capitalise on this exciting opportunity.

Grid-Connected Battery Research May Lead to Paradigm Shift

There is also some other work that Mercury has been doing that will benefit us as well as all future battery traders. This work (which also involves Transpower and the Electricity Authority) is addressing current regulations that need to be adjusted to accommodate the participation of battery stored electricity in all aspects of the NZ reserves market.

The use of large-scale batteries to store energy from times of lower usage and make it available when it’s most needed could make a real difference to the way power is supplied to homes and businesses over the coming decades, particularly as populations grow. At scale, the lowest parts of the demand curve will be raised as electricity will be generated and stored in batteries and the highest peaks of demand will be offset by electricity being re-dispatched from the batteries back into the market.

In a future world, when the investment that companies like Mercury are making in R&D has led to large-scale battery storage in New Zealand, this flattening of the supply-demand curve should lead to more efficient use of current generation capacity.

We see all these future developments as great reasons for our research investment now. And we’re proud to be pioneers in this field that has so much potential to change the New Zealand energy market to everyone’s benefit.


See how the direct grid-connected battery will work in New Zealand’s energy eco-system