How much does compressor fouling cost a gas turbine operator per year?

A GE 9-series Frame gas turbine operating under standard F9 inlet filtration ingests 10.8 tonnes of airborne particulate per year. That material deposits on compressor aerofoils, degrades blade geometry, and forces the turbine to burn progressively more fuel to hold output. 

Due to fouling, the efficiency cost on a 280 MW plant runs into seven figures annually: roughly £1.4 million at UK gas prices, or $420,000 at current US Henry Hub pricing for the equivalent fouling event. 

Today we’re taking a closer look at the cost of gas turbine compressor fouling, how it gradually builds up and what can be done to tackle the avoidable expense.

What compressor fouling is and how it builds

“Fouling”, in this context, is the build-up of foreign matter on the inner surfaces of the gas turbine compressor. It is the largest recoverable cause of gas turbine performance loss, responsible for 70-85% of all gas turbine efficiency deterioration.

Here’s how it accumulates and why it’s a problem: 

1. Airborne particulate (dust, pollen, sea salt, industrial aerosols, hydrocarbon vapours) is ingested continuously through the turbine inlet.
2. Many particles are filtered out, but some pass through the filtration system and deposit on IGVs and the first compressor stages, where the aerodynamic geometry is most sensitive.
3. The deposit changes the blade profile: increases surface roughness, narrows the flow path, and reduces the pressure ratio the compressor can develop.
4. Even small deposits have an impact, but this is a progressive process; fouling compounds with operating hours and does not plateau.
5. Greater and greater amounts of fuel are required to achieve the same output (due to increasing inefficiency), and the ultimate result is failure of equipment.

How much particulate a turbine actually ingests per year – how effective is air filtration?

It’s logical to presume that the air reaching the gas turbine compressor is foulant-free. After all, it passes through a filtration system designed for that purpose. Your choice of filtration system has a huge impact on fouling levels.

However, no air filtration system is effective enough to remove all foulants and, due to the high pressure and temperature in the compressor, any remaining contaminants are cause for concern. 

Enough air passes through the compressor on a 172 MW turbine in one year to make up a column the size of a football field rising 1,320 miles high. That volume would contain 139 metric tons of foulant (assuming 10 ppm average ambient concentration).

Standard F9 filters allow particles down to 0.5 ppm through to the compressor; HEPA filtration restricts this to 0.01 ppm, a 50-fold difference, but some degree of fouling is still inevitable. 

These real-world examples show the difference the choice of air filtration system has on compressor fouling levels:

Source: Rochem FYREWASH internal fouling load analysis, 2026. 

Foulants accumulate gradually and continuously, driving efficiency deterioration over time. Often, performance loss is not noticed for a long time, by which point the financial impact is significant.

What the efficiency loss costs in fuel

What really matters in business is money, and we can calculate the financial cost of fouling.

Step 1 – Calculating efficiency loss rate:

GE Frame 5 and Frame 9 turbines showed an average 1% increase in heat rate and 3% reduction in output per year under base load operation at 8,000 hours, without washing (actual rates vary by environment.)iii 

In a typical heavy duty axial compressor, a 1.0% loss in compressor efficiency will create a 1.1% loss in output.iv 

Step 2 – Heat rate baseline;

Modern CCGT plants (post-2010) operate at an average heat rate of 6,960 BTU/kWh. A 1% increase = 69.6 BTU/kWh additional heat consumption per unit generated.v

Step 3 – Annual fuel cost of the heat rate increase:

The fuel cost of a 1% heat rate increase for an unwashed turbine. (Real costs will vary with load factor, ambient conditions, and gas price.)

For the GE PG9301(G) at 282 MW, operating at 85% load for 8,000 hours:

• Annual generation: 282 MW x 0.85 x 8,000 hours = ~1,915,200 MWh
• Additional heat consumption at +69.6 BTU/kWh: 1,915,200 MWh x 1,000 kWh/MWh x 69.6 BTU = 133,338,720,000 BTU = 133,339 MMBtu

• At UK NBP ~£10.60/MMBtu: 133,339 x £10.60 = approximately £1,413,000/year
• At US Henry Hub ~$3.15/MMBtu: 133,339 x $3.15 = approximately $420,000/year*

For the GE LM2500 at 25.06 MW, operating at 85% load for 8,000 hours:

• Annual generation: 25.06 MW x 0.85 x 8,000 hours = ~170,408 MWh
• Additional heat at +69.6 BTU/kWh: 170,408 MWh x 1,000 kWh/MWh x 69.6 BTU = 11,860,396,800 BTU = 11,860 MMBtu

• At UK NBP ~£10.60/MMBtu: 11,860 x £10.60 = approximately £126,000/year
• At US Henry Hub ~$3.15/MMBtu: 11,860 x $3.15 = approximately $37,400/year*

*Note: the UK and US figures represent the same physical fouling event (a 1% heat rate increase on the same turbine) priced at two different regional gas markets. NBP is currently running well above Henry Hub, which is why the UK cost is proportionally higher. 

What a washing programme costs by comparison

While gas turbine compressor fouling results in considerable expense, there are steps you can take to reduce your costs. Gas turbine compressor washing removes foulants to maintain efficiency and reduce unnecessary additional fuel costs:

• Regular online (fired) washing arrests fouling accumulation between offline wash events; the efficiency loss curve flattens rather than running unchecked.
• Offline (crank) washing performed at appropriate intervals recovers the deeper fouling that online washing cannot fully address.

The price of initial hardware installation (e.g. wash nozzles, wash skids etc) and the ongoing cost of cleaning chemicals is significantly lower than revenue otherwise lost due to inefficiency. Specific savings vary by turbine type, application and volume but can be calculated on a case-by-case basis.

Get in touch

As shown, gas turbine compressor fouling is an unavoidable problem and extremely costly if left unchecked. To tackle the issue, we specialise in gas turbine compressor cleaning. Our range of products, including cleaning chemicals, is used at thousands of plants around the world, helping customers save money by reducing fouling. 

If you’d like to discuss fouling at your gas turbine site and discover how we can help you save money, please get in touch. Our knowledgeable team will be happy to discuss your specific requirements.