Your questions answered: Microgrids 201: Integrating renewables and battery storage into your power solutions
This presentation is designed to educate energy professionals (CSEs, owners, distributed energy managers) regarding microgrid and distributed generation projects incorporating battery storage with multiple energy sources including renewables. During this webcast, the presenters discussed the unique benefits and challenges of incorporating battery storage solutions into a microgrid, and provided real-world examples of successful projects including lessons learned and best practices identified.
Presenter Tom Drake, regional sales manager for Gas Power Systems, MTU Onsite Energy, responded to questions not answered during the live Microgrids 201: Integrating renewables and battery storage into your power solutions webcast on June 18, 2019.
Question: What are typical battery energy storage systems for hospitals and or schools? Are there turnkey installations for these energy storage systems? Are there any special heat mitigation systems needed for energy storage systems?
Tom Drake: Battery solutions are always designed to the application. There really isn’t a cookie cutter solution. Heat from the inverter is managed by the HVAC system.
Q: How do gas powered systems integrate with renewable and battery storage type microgrids?
Drake: This was the focus of the presentation. Batteries and engines are used to support the nondispatchable renewable energy resources.
Q: How long do batteries last under load, i.e. when should they be replaced?
Drake: Depends on the application. MTU Energy Pack is designed for 3,600 cycles. Performance guarantees are issued after the specific application is understood.
Q: Can rural solar power be used in a local microgrid?
Drake: Yes. One of the emerging trends is pairing solar PV with diesel generators and batteries for a lower cost of power.
Q: Some generator manufacturers rebrand PV systems and inverters, allowing them to offer comete systems: generators, PV and control. What does MTU have to offer in regard to PV?
Drake: At this time, we don’t plan to offer PV systems rebranded as MTU’s.
Q: Why do you call them renewable sources?
Drake: They aren’t specifically renewable, but paired with renewable, they can optimize those resources.
Q: My understanding is solar energy is expensive due to the panels’ cost in addition to the storage system cost. Is it worth installing the system in residential scale or utility scale?
Drake: In North America, incentives and market pricing dictate the location of solar paired with battery energy storage systems. High prices in California and a push for renewables allow for favorable return on investments (ROIs).
Q: If you’re absorbing energy from the grid while you’re discharging your storage device, how can you ensure your storage device is supplying your equipment and not pumping energy back into the grid? Or does it not matter if it’s going into the grid; you’ll be selling that energy at the same cost as you’re buying it?
Drake: They can’t be charged and discharged at the same time. The switchgear and protective relays will ensure that power is not fed back onto the grid.
Q: Where are high C and low C batteries applicable?
Drake: Quick discharge rates are good for frequency and voltage regulation and long discharge rates are good for backup power and time shifting of renewables.
Q: What is resource adequacy and how do you determine what it should be?
Drake: When either local generation capacity or transmission/distribution capacity is insufficient to support loads, batteries can be added to the system to manage the loads.
Q: By what means are the batteries charged – photovoltaic or utility?
Drake: Batteries can be charged by various energy resources.
Q: Do you have any medium- to large-scale systems in Canada that would help support a 40,000-population university?
Drake: The size of the electrical load is more important than the population.
Q: Do you have a financial model (spreadsheet) that we can use to product ballpark ROI numbers for peak shaving systems?
Drake: Yes, we use a program to model ROI depending on the application.
Q: Can we use electric car batteries as storage during nighttime when they are overcharged?
Drake: There is the potential for those to be used in that application.
Q: Has any special considerations been given to charging the battery bank (1 MW scale) with PV, e.g., charge controlling, battery charge rate, typical charge rate?
Drake: No, the transformer and inverter are bi-directional, able to discharge and recharge. The main consideration is the rate of charge and discharge needed for the application.
Q: When is NFPA 855 coming out?
Drake: It will be released on August 20, 2019.
Q: What’s the typical NEMA rating on the enclosures? Are they vented or designed with rupture panels?
Drake: I’m unsure of the NEMA rating, but it is a fully engineered enclosure system with control areas, HVAC system and fire suppression.
Q: Are there any NFPA or UL or other national/international agencies that have codes/standards to govern battery energy storage system (BESS) design?
Drake: Yes, UL and CSA both have various standards.
Q: When power is lost, how does battery storage provide uninterruptible power before the generator starts?
Drake: That would be part of the switchgear and intelligent controls to monitor loss of power and that time would be measured in milliseconds.