Diesel generators are widely used for off-grid power, but fuel costs represent a significant operating expense. Battery storage integrated with generator systems can reduce diesel cost with battery storage by minimizing generator runtime and operating generators at optimal efficiency points. Injet HanCang has developed hybrid systems that reduce diesel cost with battery storage across mining, telecom, and industrial applications. This article presents the technical approach, fuel saving data, and economic analysis.
Battery storage reduces diesel consumption through three mechanisms.
The first mechanism is load leveling. Generators operate inefficiently at partial load. A typical diesel generator has efficiency of only thirty percent at twenty percent load but reaches forty percent efficiency at eighty percent load. By using battery storage to handle low-load periods, the generator can be turned off or operated at higher load, reducing fuel consumption per kilowatt-hour produced.
The second mechanism is peak shaving. Generators must be sized for peak loads, which may occur for only a few hours per day. The generator operates at low load for most of the day. Battery storage supplies the peak load, allowing a smaller generator to operate at higher average load. The smaller generator has lower fuel consumption than the larger generator at the same average load. The third mechanism is generator start reduction. Generators consume fuel during start-up and warm-up periods. By using battery storage to bridge short-duration power needs, the generator starts fewer times per day. Injet HanCang data shows that reducing starts from twenty-four per day to six per day saves approximately five percent of fuel through reduced start-up consumption.
Injet HanCang has measured fuel savings across multiple installations designed to reduce diesel cost with battery storage. The table below shows data from three representative sites. Site Type Generator Size Battery Size Previous Fuel per Day Current Fuel per Day Fuel Saving Telecom tower 50 kilowatts 200 kilowatt hours 110 liters 38 liters 65 percent Mine camp 300 kilowatts 1000 kilowatt hours 580 liters 210 liters 64 percent Water pumping 150 kilowatts 500 kilowatt hours 310 liters 115 liters 63 percent The telecom tower site previously ran a fifty-kilowatt generator continuously to power a twenty-kilowatt load. The generator operated at forty percent load, achieving efficiency of thirty-two percent. With battery storage, the generator runs only six hours per day at full load to recharge the battery. The generator now operates at fifty kilowatts output, achieving efficiency of thirty-eight percent. Fuel consumption per kilowatt-hour delivered decreased from zero point four two liters to zero point one five liters.
Injet HanCang uses a predictive control algorithm to reduce diesel cost with battery storage. The algorithm considers three inputs: the current battery state of charge, the load forecast for the next six hours, and the fuel consumption curve of the generator. The algorithm calculates the optimal generator start time and run duration. The objective is to maintain battery state of charge between forty and eighty percent while minimizing total fuel consumption. The control algorithm was developed using data from three years of field operation. The algorithm includes a learning function that adjusts predictions based on actual load patterns. For example, if the site consistently experiences higher loads in the afternoon, the algorithm starts the generator earlier to recharge the battery before the peak load period. The learning function reduces prediction error from fifteen percent to five percent over the first month of operation.
Injet HanCang also implements a fuel consumption monitoring system. The system measures fuel flow rate during generator operation and logs cumulative consumption. Operators can view fuel consumption data in real-time and compare against historical data. The monitoring system provides alerts if fuel consumption deviates from expected values, indicating potential maintenance issues.
The economic benefit of reducing diesel cost with battery storage depends on fuel price, system cost, and operating hours. Injet HanCang developed an economic model for a typical mining site with a one-hundred-fifty-kilowatt average load and a three-hundred-kilowatt generator. The model uses a battery storage system of five hundred kilowatt hours and a one-hundred-fifty-kilowatt inverter. The model assumptions are as follows. Diesel price is one point two dollars per liter. Generator maintenance cost is twelve thousand dollars per year for the generator-only case and six thousand dollars per year for the hybrid case due to reduced runtime. Battery system cost is two hundred thousand dollars. Inverter cost is fifty thousand dollars. Installation and commissioning cost is thirty thousand dollars. Total system cost is two hundred eighty thousand dollars. The annual fuel consumption for the generator-only case is one hundred thirty thousand liters, costing one hundred fifty-six thousand dollars. The annual fuel consumption for the hybrid case is forty-six thousand liters, costing fifty-five thousand dollars. The fuel saving is one hundred one thousand dollars per year. The maintenance saving is six thousand dollars per year. Total annual saving is one hundred seven thousand dollars. The payback period is two point six years.
Several technical insights have emerged from Injet HanCang projects designed to reduce diesel cost with battery storage. The first insight is that battery sizing significantly affects fuel savings. A battery that is too small requires frequent generator starts, reducing start-up savings. A battery that is too large increases upfront cost without proportional fuel savings. Injet HanCang recommends battery capacity of four to six hours of average load for optimal fuel reduction. This sizing provides sufficient storage for overnight loads while keeping battery cost within economic limits. The second insight is that generator selection matters. Generators with electronic governing and high compression ratios have better partial load efficiency.
Injet HanCang specifies generators with variable speed operation for hybrid applications. The variable speed generator adjusts engine speed to match the required power output, improving efficiency by five to eight percentage points compared to fixed-speed generators. The third insight is that ambient temperature affects fuel consumption. Generators consume more fuel at high ambient temperatures due to reduced air density. Battery storage allows the generator to run during cooler periods of the day, when the generator operates more efficiently. Injet HanCang systems include temperature scheduling that prioritizes generator operation during early morning hours in hot climates. This scheduling reduces fuel consumption by an additional four percent.
A mining site in Western Australia implemented an Injet HanCang system to reduce diesel cost with battery storage. The site previously operated two three-hundred-kilowatt generators in parallel to supply a two-hundred-fifty-kilowatt average load. Peak loads reached six hundred kilowatts during drilling operations. The site consumed one hundred seventy thousand liters of diesel per month at a cost of two hundred thousand dollars. Injet HanCang installed a one-thousand-kilowatt-hour battery storage system with a five-hundred-kilowatt inverter. The existing generators were retained but operated only one at a time. The battery supplies the load during low-demand periods and assists during peak demand periods. The generator operates for six hours per day, recharging the battery while supplying the load. After twelve months of operation, the site reduced diesel consumption to fifty-eight thousand liters per month. Monthly fuel cost dropped to seventy thousand dollars. The annual fuel saving is one hundred thirty-two thousand liters, valued at one hundred fifty-eight thousand dollars. The system payback period was twenty-two months. The generator maintenance interval extended from one thousand hours to three thousand hours due to reduced runtime.
The payback period ranges from two to five years depending on fuel price and system cost. Sites with diesel prices above one dollar per liter typically achieve payback within three years.
Yes, Injet HanCang provides retrofit systems that add battery storage and control to existing generators. The existing generator must have compatible controls for remote start and stop. Most generators manufactured after 2015 have this capability.
The battery system requires minimal maintenance compared to the generator. Annual capacity testing and visual inspection are recommended. The cooling system requires filter cleaning every three months.
No, battery storage reduces but does not eliminate generator runtime. The generator must run periodically to recharge the battery. Injet HanCang systems typically reduce generator runtime by sixty to seventy percent.
For systems with solar PV, the generator automatically starts when battery state of charge falls below the set threshold. The system operates in generator-charging mode until the battery is sufficiently recharged.
Injet HanCang systems demonstrate that battery storage significantly reduces diesel cost with battery storage through load leveling, peak shaving, and reduced generator starts. Field data shows fuel savings of sixty-three to sixty-five percent across telecom, mining, and water pumping applications. The predictive control algorithm optimizes generator operation based on load forecasting and generator efficiency curves. Economic analysis shows payback periods of two to three years for typical installations. Technical insights regarding battery sizing, generator selection, and temperature scheduling further improve savings. Sites interested in reducing diesel cost with battery storage can request a fuel reduction assessment from Injet HanCang.