What Is Cycle Charging & Is it Green?

The growing interest in Battery Energy Storage Systems (BESS) is an example of this – a battery-run energy storage unit to produce cleaner, immediate energy. But what is cycle charging? And, more importantly, is this process considered ‘green energy’?  

For the purpose of this article, we’ll refer to real data from one of our BESS units on a Tier 1 construction site in Sydney.  

Here, we’ll focus on the process of cycle charging of the battery in BESS units, like our POWR2 POWERBANKS, if this is considered ‘green energy’ and what this could mean for construction sites.  

So, let’s say we have a BESS paired with a diesel generator to power a temporary site office complex. 

Cycle Charging (CC) is when the battery takes the role of being the main supply of energy for the office complex and the generator charges the battery when required. This means you’re essentially placing a battery into the power generation mix between the load (in this case the office complex) and the diesel generator.  

You can control when you want the generator to start charging the battery through programming the battery State of Charge (SOC). For example, you can set the generator to kick-in to re-charge the battery once the SOC depletes to 20%.  

Once the SOC reaches 20%, the battery will send a signal to the generator that it’s ready for charging. The generator will start, warm itself up and once it’s ready, begin charging the battery. While the battery is charging, it will power the office complex simultaneously.  

When the battery reaches a SOC of 98%, it will signal the generator to cease sending energy, cool down and turn itself off. The battery will now re-assume the role of providing power to the load until it depletes to the 20% SOC setpoint again.  

Welcome to cycle charging. 

In the case of our temporary office example, CC was able to lower overall diesel fuel consumption. Instead of the generator powering the complex 24/7, it’s only operating for about 30% of the daily cycle.  

While this depends on the load, this is carefully taken into consideration for each client when a unit is deployed. In any case, the battery can keep the diesel generator offline for extended time periods. Below is a graph displaying how cycle charging can benefit your operations:  

This graph displays real data of the load consumption (red), the battery SOC (blue line) and the generator operating profile (green).  

As you can see, the construction site was able to reduce the generator run time significantly by utilising a battery to perform CC. In this case, the benefits of this include:  

• Reduced diesel consumption
• Reduced operating hours (longer duration between servicing and refuelling)
• Optimal operating load for the generator (zero chance of glazing due to low loads)
• Silent running for a majority of the day

While we have used a temporary office complex as an example, CC benefits are totally dependent on a few variables. This is why Blue Diamond will scope the parameters of your project and your power needs up provide a customised solution.  

With that said, battery technology counteracts many drawbacks of using diesel on construction sites, especially for those experiencing uneven loads on a diesel generator. 

For more information on the benefits of utilising a BESS unit for your construction project, click here.  

It’s complicated.  

On one hand, CC is an easy way to drastically begin reducing carbon and emissions. From what you can see in the data, CC is able to significantly reduce the run time of the diesel generator resulting in a huge decrease of fuel consumption and harmful emissions. Also, when the on-site generator is running, it does so at full power, making it far more efficient. So yes, it counts as green energy.  

On the other hand, green energy doesn’t mean it’s renewable energy. Having a BESS is an excellent way of storing renewable energy, however, generally it isn’t possible to solely rely on solar or wind. Because of this, in the case of the POWR2, the battery will always be paired with a diesel generator. So, until we begin to look at Renewable Diesel options like Hydrogenated Vegetable Oil (HVO), we will always be using fossil fuels to provide energy.  

 This is where we see great potential with CC utilising a diesel generator. Over time, we can transition to HVO and future renewable fuels or where space allows we can easily introduce solar panels to reduce diesel consumption even further. 

As the journey to Net Zero is gaining momentum, it is essential for construction sites to utilise readily available technology like BESS units to start making a difference. The key here is to start. Blue Diamond is ready to support your energy transition and help the Australian construction industry kick-start the journey into new technologies for smarter construction. Get in touch with the team today.