„Optimising the cost-effectiveness of a biogas power station by means of smart use of ecologically produced power combined with smart networking of all systems involved.“
Head of Office South, Germany
For Biogas Gröber Ruf GmbH & Co. KG, a producer of regenerative power in Fuchstal, southern Germany, Mr Kirmaier was responsible for completing a turnkey UPS storage solution (160 kVA / 462 kWh).
PN: Mr Kirmaier, would you kindly tell us about your customer and their field of business, in brief?
Kirmaier: Biogas Gröber Ruf GmbH & Co. KG – as the name implies – is a company which generates energy on a climate-neutral basis. Using the gas generated from biomass, the customer drives BTTP (Block type thermal power station) gas motors which generate electricity and heat with a high degree of efficiency. In close partnership with local farmers, the customer – which is based in Fuchstal, Bavaria – obtains the required biomass from cultivation in the region. In addition, the customer makes use of the roof areas of its operational buildings to generate photovoltaic energy.
We have come to appreciate how future-oriented and innovative this customer is. We immediately noticed that this Company’s fundamental policy is to give priority to the sparing and intelligent use of ecologically generated power.
The Company’s affiliations include its capacity as a partner of the Fuchstal Energy Future project, which is funded by the Federal German Ministry for the Environment and Natural Conservation. Photovoltaic systems, a hydro power station, a municipal wind farm and Biogas Gröber Ruf’s biogas system have all been combined, within this project, to form an innovative energy grid that spreads across a number of communities.
The goal of logically applying renewable energy sources then gave rise to the customer’s further considerations with a view to optimisation. We were able to provide the customer with tremendous support. Previously, in phases where there was no solar radiation – in other words on rainy days or at night – the plant’s own electrical power needs in terms of operating the system were covered on a round-the-clock basis by the biogas BTTP. The power draw entailed in that context, representing approximately 9% of the generated power, was consequently no longer available to be fed into the power supply grid.
By virtue of investing in an energy storage system which provides for buffer storage of the surplus solar power generated in the daytime – and not required to cover the plant’s own needs – it was possible to achieve a significant increase in the proportion of own-generated solar power that could be used in-plant. That meant that only a residual quantity – approximately 2% of the more ecologically valuable biomass power (also available at night) – could be drawn upon to cover the plant’s own requirements.
It was possible to increase the proportion of own consumption of generated solar power to the commendable figure of 80%. And there is a further benefit from a commercial viewpoint, because under EEG (German-language abbreviation for Sustainable Energy Regulations) the biomass power feed earns higher payment than solar power does.
PN: In other words, a greater proportion of the more financially profitable biomass electricity can be fed in: an undeniably attractive layout. Mr Kirmaier, you cover southern Germany. Prior to this project, did you already have an ongoing business relationship with Gröber Ruf GmbH & Co. KG?
Kirmaier: For us, this customer was a “new acquisition”. On the other hand, our initial contact with them came about via a company which is networked with ourselves. For a considerable time, Mr Ruf had been searching in vain for a system partner who could be entrusted – in the capacity of a fully responsible turnkey partner – with the operation of an energy storage system consisting of a combination of the components of a current transformer, a battery system and incorporation in the energy management system. Their company then received a crucial hint – from a company which is in partnership with ourselves (in the field of battery technology) – thus putting them in touch with BENNING.
- Energy accumulator + UPS
- Modular system
- Connection direct to 400 V AC
- No transformer needed
- Inverter output 160 kW
- Flexible expansion capability
- Modular-design li-on energy accumulator
- Projected useful battery life: 10 years
- Reserve capacity for UPS consumers
- Reserve capacity for particular operating cases
PN: Accordingly, we could say – possibly with a little exaggeration – that you won the order because BENNING is the only supplier who was prepared to accept such a complicated challenge?
Kirmaier: In fact it was the customer who later told us (in the course of a project meeting) about the long and futile search they had previously undertaken, to find a suitable provider. And they emphasised how particularly concerned they had been (on top of all the technical and financial aspects) by the fact of the need to have competent consultation at the outset when it came to the eventual order being issued.
Perhaps I could best characterise the situation’s complexity as follows:
The infrastructure already in place with the customer consisted of several biogas generators, a solar power system and various feed inverters. The plant’s consumption and energy feed was controlled by an EMS – energy management system – already in place with the customer. In addition to the hardware, in other words, there was the communications link for our UPS and storage systems together with the BMS – Battery Management System – feeding into the customer’s data flows.
PN: You mentioned technical aspects, just now. Why did the customer want a combination of battery systems and UPS plant? Would an energy storage system not have been adequate?
Kirmaier: Amongst other functions covered by the UPS system, it also provides for an increase in the operational reliability of the plant, because the sophisticated automation system consisting of sensors, evaluation computers, actuators, feed pumps and managed stirring drives could not tolerate any grid fluctuations / failures. Any fault would have given rise to considerable complications in the operation of the plant. And a worst-case occurrence would have given rise to safety-critical situations, because plant parameters such as gas pressure or volumetric levels would then have been unavailable.
In order to avoid such a scenario, a portion of the energy which is available from the batteries is not released to cover our own needs, but is kept in reserve to guarantee continued supply for the sensitive plant technology.
In the event of any grid failure, the ENERTRONIC modular Storage system – which operates simultaneously as a storage system and as a UPS – will cut in and support the reliable continuation of operation by virtue of its energy reserve.
In addition to the basic function which covers the storage and release of the climate-neutral production of electrical power, then, the system – without any significant additional costs – provides absolutely interruption-free, continued power supply to sensitive supplies should any grid failures arise. This comes in conjunction with an extended service life, since it filters out any of the grid impurities such as harmonics or transient voltages that would otherwise reduce the service life of the plant components – most of which are expensive.
PN: So, looking once again at ENERTRONIC modular Storage: Could you kindly provide us with a brief description of which system components were installed and commissioned by BENNING Service in the autumn of 2020, please?
Kirmaier: The outcome of the early-2020 planning & analysis phase was the requirement, on the hardware side, for a system consisting of ENERTRONIC modular Storage with 160 kVA output (4 modules, each providing 40 kVA), a BMS and a li-on energy accumulator of modular layout, with an energy capacity of 462 kWh (2 x 7 x 33 kWh). It was not viable – for financial reasons – to consider a solution with conventional lead batteries, although the ENERTRONIC modular Storage solution is also suitable for such an application. It was possible to make connection directly at the low-voltage level (400 V AC / VDE AR-N4105). This approach meant that there was no need for the plant to invest in its own transformer. The system’s design is based upon maximum availability, with redundancy. The advantages of modular architecture – such as quick & straightforward servicing, flexible scaling and modest space requirements – were as convincing as the benefits of high system energy efficiency, added safety and a quicker breakeven time.
PN: Just there, you emphasised on the hardware side. Why was that?
Kirmaier: That’s right: an important module of the project was the smart networking of the already existing EMS (type S7) with its new components and specifically with the BMS. The corresponding integration was carried out by our engineers hand-in-hand with the customer’s EMS specialists. The Monitoring and Control Unit (MCU) – developed by ourselves and used in many areas of industry and telecommunications – provides for the widest range of manufacturers to be connected up to the EMS with a wide range of supported protocols and interfaces.
PN: Mr Kirmaier, many thanks for speaking to us today. It was most interesting for us to learn how a biogas power station can be operated with such great efficiency – by virtue of investing in an energy accumulator system with UPS capability – can be operated not only with greater safety but also using the various payment models under EEG (sustainable energy regulations) – looking at things from the commercial viewpoint – and with such impressive efficiency as to ensure a rapid ROI (return on investment).
Benefits of storage systems with UPS capability
- Economy of operation can be achieved via:
- Peak shaving
- Load levelling
- Optimisation of power draw (“7000-hour rule”)
- Day-to-night energy transfer
- Energy reserve can be defined flexibly
- Storage during low-load phases
- Additional output during high-load phases
- Suitable for lead and lithium batteries
- Own consumption optimised
- Safe UPS operation (VFI-SS-111)
- Power factor correction
Advantages of the ENERTRONIC modular Storage
- Maximum availability
- Minimised operating costs
- Variable component concept can be achieved by:
- Storage and UPS function
- De-centralised, parallel architecture
- Hot plug system with modular expansion facility
- Flexible battery configuration (secondary battery, group battery, individual battery)
- Can be used in conjunction with regenerative energy systems such as solar power, hydro or wind systems
- Option of connection to low-voltage grid as per VDE AR-N4105
- High efficiency
- Rapid return on investment