Why Do Electricity Bills Remain So High? The Problem Is Not Power Consumption, but Transformer Capacity Charges
After replacing equipment with energy-efficient models, carefully scheduling production outside peak hours, and tightening electricity-use management, why does the total electricity bill at the end of the month still remain outrageously high despite every effort to save power?
The root cause is that factories focus only on how many kilowatt-hours they consume while overlooking a fixed item on the electricity bill—the basic electricity charge. This charge has nothing to do with monthly power consumption; it depends solely on the declared transformer capacity. As long as the transformer remains connected to the grid, the full amount is charged every month, regardless of how much or how little electricity is used.
Transformer capacity charges are the largest “passive expense” in a factory’s electricity costs, and ordinary cost-reduction measures cannot reduce them. When this is compounded by high-priced electricity purchases during peak periods, power-factor penalties, and surcharges for exceeding transformer capacity, corporate profits continue to shrink.
Faced with these challenges, a single energy-saving device is far from sufficient. The key is a systematic solution that can reduce both capacity charges and energy-consumption charges. Gas-fired internal combustion generator sets are a targeted solution well suited to this type of electricity-cost problem.
I. Why Can’t Conventional Energy-Saving Measures Reduce Capacity Charges?
When applying for transformer capacity, most factories leave a safety margin—not only to handle instantaneous peak loads during production, but also to allow for future expansion. This “bigger is safer” selection logic leaves plants operating for long periods with oversized transformers: the average daily load is far below the transformer’s rated capacity, yet the full capacity charge must still be paid. Even if workshop output is reduced or production lines are shut down, this fixed charge is not waived.
There are two common approaches: installing on-site generation equipment, or adopting energy storage and variable-frequency drive upgrades. Neither, however, addresses capacity charges at their source. On-site generation can replace only part of the electricity purchased from the grid, thereby reducing energy-consumption charges. Energy storage merely shifts electricity use from peak to off-peak periods without changing total consumption. Variable-frequency drive upgrades improve equipment efficiency, but likewise reduce only energy-consumption charges. These methods save money on the electricity used, but they do not change the cost of reserving capacity. Capacity charges are fixed monthly expenses; as long as the declared transformer capacity remains unchanged, the amount payable will not decrease.
II. How Can Gas-Fired Internal Combustion Generation Reduce Capacity Charges at the Source?
Conventional energy-saving measures help factories “use less electricity,” whereas gas-fired internal combustion generator sets help them “draw less electricity from the grid.” In industries such as coking, metallurgy, and chemicals, by-product gases such as coke-oven off-gas and blast-furnace gas were often vented directly in the past. Gas-fired internal combustion generator sets can convert these waste gases continuously into electricity, 24 hours a day, to supply the plant’s baseload demand.
Once the gas-fired units support the baseload, the plant needs to purchase from the grid only the difference between its total load and its self-generated electricity, substantially reducing the peak power drawn from the external grid. If the plant’s actual peak grid demand remains consistently below its originally declared capacity, it can apply to the power utility for a permanent capacity reduction. Based on a prevailing basic tariff of RMB 25 per kVA per month, every 1,000 kVA reduction in capacity directly saves RMB 300,000 per year. At plants equipped with multiple transformers, idle standby transformers may also be taken out of service during the production off-season, with basic electricity charges waived for the shutdown period.
III. Additional Benefits Beyond Capacity-Charge Reductions
The value of gas-fired internal combustion generator sets goes beyond reducing capacity charges. During peak-tariff periods, self-generated electricity can replace expensive electricity purchased from the grid, further lowering energy-consumption charges. The units can also effectively shave peaks in grid demand, eliminating surcharges for exceeding contracted capacity at the source.
The units also provide reactive-power regulation, which can effectively improve the plant’s power factor. This not only avoids power-factor adjustment penalties, but may also qualify the plant for dedicated power-factor incentives.
In addition, waste heat from the units’ exhaust gas and jacket water can be recovered for plant heating, raw-material preheating, process heat supplementation, and similar applications. This replaces conventional gas- or coal-fired heating and further reduces overall energy costs.
IV. Suitable Applications
Gasfired internal combustion generator sets are not suitable for every factory. A comprehensive assessment should be conducted across the following four dimensions:
1. Gas Supply
The factory continuously and reliably produces large quantities of by-product gas, such as coke-oven gas, blast-furnace gas, or biogas, or it has access to a piped natural-gas supply. Without a stable gas source, the basic conditions for implementation are not met.
2. Baseload Electricity Demand
The plant must have a continuous and stable baseload electricity demand to ensure that all self-generated electricity can be consumed on site and that surplus generation is not wasted.
3. Transformer Capacity
A transformer capacity of at least 315 kVA is recommended, with capacity charges representing a relatively high share of the monthly electricity bill. Only then will the cost savings from capacity reduction be sufficiently significant.
4. Heat Demand
If the plant has heating, hot-water, steam, or other thermal loads, waste heat can be used simultaneously to further reduce overall energy costs.
Based on these four dimensions, typical suitable users include companies in coking, coal chemicals, metallurgy, ceramics, glass, pharmaceuticals, and food processing, as well as livestock-farming and wastewater-treatment businesses that can produce biomass-derived biogas.
V. Conclusion
For factories subject to a two-part electricity tariff, the key to reducing electricity costs often lies not in “saving electricity,” but in “reducing capacity.”
The advantage of gas-fired internal combustion generator sets is that they provide a complete cost-reduction pathway: converting by-product waste gas into electricity for self-consumption to replace expensive grid purchases → applying for a capacity reduction or taking standby transformers out of service after substantially lowering grid demand → recovering waste heat to further reduce energy costs.
Turning “passive expenditure” into “controllable cost” and converting rigid costs that have drained the business year after year into stable, long-term operating profit—this is the true value of gas-fired internal combustion generator sets.
