When coupled directly with solar, energy storage has obvious benefits – the opportunity to increase self-consumption of PV-generated electricity, as well as adding uninterruptible backup power supply, especially at smaller scales. However, the use of larger scale storage to contribute to grid stability, offers an interesting ‘twofer’ (two-for-one) driver for PV and other renewable energy that is being explored at a 67.8MW solar farm in Germany by developer BELECTRIC.
Firstly, and most importantly from a ‘bigger picture’ point of view, it can help render arguments against the variable nature of PV as somewhat redundant, as stable grids can accommodate greater penetrations of renewable energy. Secondly, as in the case of the latest project from BELECTRIC, grid storage batteries could provide additional revenue streams, from playing into the market for ancillary services to the grid, such as frequency regulation. Andy Colthorpe spoke about the project with BELECTRIC’s UK managing director Duncan Bott and Tim Mueller, chief executive officer of BELECTRIC’s solar research and innovation subsidiary, Adensis.
Alt Daber is a pretty big solar project. Can you tell us about some of the thinking behind the installation of a 2,000kWh energy storage facility once the solar portion of the project was completed?
Tim Mueller: We started Alt Daber as a PV power plant and began building in 2011 and it was also completed that year. We were thinking it would be very nice to add a storage system to this power plant. We came to this idea because the Transmission Network Operator (TNO) which was connecting the Alt Daber PV plant would have a lot of problems getting the energy away from this PV plant.
We were thinking – how could we aid this problem, how could we help? The first idea was always storage systems and we had started maybe three years before with the design of a storage system which would be suitable for PV power plants in stationary applications. So we were thinking, why not apply it to our power plant in Alt Daber?
When it comes to solar coupled directly with storage, a lot of the talk we have heard has centred on ‘load shifting’ applications, often conferring the direct benefit or value onto the owner of the PV system rather than using the batteries for grid stabilising. Why is the Alt Daber project more concerned with using storage for grid stability?
TM: The more we got involved in [looking at storage for Alt Daber], the more we found out that to store energy to shift it from one hour to another or to shave the peak, would be a nice idea but would not be profitable. So it’s not the time yet to do that – for business models to shift energy from one hour to another, using electrical storage systems. But in the end we thought, well, it should be something we have to do, or have to construct within the next couple of decades, otherwise we will not have a higher penetration of renewable systems at some point. We were thinking, what would be possible commercially and what would also be necessary?
We found out that for the moment the biggest problem is not to shift energy but the biggest problem right now is to stabilise the grid, so this is something that is a bit ahead but we will need that already in the next couple of decades or even the next few years.
That’s the technical side – what are some of the market drivers for this kind of grid stabilising project, specific to Germany, which made the Alt Daber project possible?
TM: In Germany, it [the grid] is pretty stable but still we will need it. Frequency regulation is one of the main regulatory possibilities to stabilise the grid. This is done by conventional power plants which are more and more being pushed out in Germany and Europe. At the same time, we also need grid stabilisation capacity. In order to not stop the trigger for the building of PV power plants we need to replace that grid stabilisation technology, we need to replace conventional power plants wherever they go out of business. So this is what we did in Alt Daber.
We installed the storage system, battery plant, with the purpose of doing frequency regulation, commercially under the German grid regulation market. There is a weekly tender and you offer your power, your frequency regulation or frequency response power and you are awarded, or not, depending on the price you offer. We have done a lot of talks with National Grid in the UK and they’re doing very similar things
Do you think these kind of devices, storage in combination with solar, could make large-scale solar more attractive to governments and electricity network operators? The theory would suggest it should but as we know, the politics and economics behind these things do not always follow the science and technology as closely as we would hope!
Duncan Bott: The various network operators around the world are starting to progress towards the recognition that historically, it was thought that renewable energy was disruptive to the network and now that’s starting to shift towards a recognition that actually, renewable energy can offer solutions to stabilising the national networks and we are progressing toward recognising how that is achievable.
Through the innovation of technologies, which BELECTRIC is trying to be something of a market leader on, we can now add additional business models to what was once just this simple model of produce, export and sell energy. So I guess what we’re doing here is demonstrating that it’s not just about the battery in the box. There’s a lot more behind the hybridisation of solar and these technologies, and solar and these business models, to enable us to make that step forward in the future into the world of either lesser subsidies or no subsidies.