Jacobs group manager of power transmission and distribution Dr Kerim Mekki talks about the possibilities of utility-scale storage and why Australia reminds him of Africa.
How are you involved in the surge of wind and solar projects planned for this year and next?
We are the purchasing manager and owner’s engineer on the AGL Silverton wind farm and worked on the Nyngan and Broken Hill solar plants, 153MW of utility-scale solar. As consultants we are mostly here to provide engineering services; we support clients from an early stage to the commissioning and delivery. We can be on the owner’s engineer side, we can be supporting the contractor with designs, we can be on the due diligence side with bankers.
Are your clients thinking about storage?
We’ve done one of the first large battery storage systems, which is bigger than 25MW. It’s quite a progressed project, near commissioning stage, but that’s all I can tell you. The difficulty with battery storage is it all tends to be quite confidential.
What role do you see batteries filling?
We’ve been an early adopter of battery storage. The next interesting phase in Australian networks and markets will be how the batteries provide synthetic inertia and how that will promote more penetration of renewables in the system.
But some people say batteries can’t provide inertia…
Yes and no. The battery systems respond so fast that the concept of inertia is gone. Before your primary control steps in everything is driven by inertia; the concept of synthetic inertia is not the optimal response really from a battery system but the frequency control. It’s a high-performing piece of equipment and the fact that it’s so fast to respond makes it an excellent tool. It’s worth discussing how we regulate frequency but the more difficult aspect is how we reward someone providing frequency control.
Where do you see the most efficient use for storage?
I see a very powerful use of batteries in replacing spinning reserve, typically in a power plant. If you have five turbines running you will keep one at a low generation point so that if a unit trips it can pick up the slack and avoid any frequency drama. Typically this spinning reserve thermal unit is operating at a low point, so it’s very inefficient. It’s not designed to be efficient at this point. That’s a function battery storage can provide very easily. Suddenly if there is an event the battery comes into the picture and compensates for the time to start another unit – 5 minutes, 20 minutes, depending on your generation type – and provides this spinning reserve capability. That is a very smart usage of battery storage.
Is the technology advanced enough to fulfil the role?
Yes. I’ve been working on this about six months. I wouldn’t have said yes in the first two months but now, yes, I’ve seen how capable it is.
What’s your view on existing transmission limiting opportunities for projects?
The network design of the last 50 years wasn’t meant for distributed generation. A typical example is the limitation you will find in different areas of the network, where the operation is at 220kV. Being at 275kV will allow a lot of renewable scale projects to be viable. There are bottlenecks at the moment for projects to connect. Five or 10 years ago there wasn’t any discussion about these projects, so it’s a big shift for the network to update and enable connections.
Around the Hunter Valley in NSW there is acknowledgment that one renewable project by itself won’t be able to pay for the infrastructure for it to connect but if there is a mass of them concentrated in one location then there can be a mechanism to get connection at a decent price, which can be split between the participants.
And now tell us a little bit about yourself…
I’m a product of the French engineering school and have been moving around for five years in developing countries working on World Bank projects – Afghanistan, Morocco, Egypt, Algeria, Swaziland, Togo, Benin, Burkina-Faso, Romania, a range of countries. Mostly we were rebuilding assets after civil wars, so a lot of interesting travelling.
What’s really interesting is if you look at the way Australian networks operate – the way the loads are distributed and the length of line – there are a lot of similar issues in Africa because the density of population is not that high and it’s not unusual to have to bring a couple of hundreds megawatts over a thousand kilometres, which you won’t find in Europe, North America or most of Asia.