Retrofit Emission Control Device (RECD) for DG Sets: Ensuring Compliance with CPCB Norms

With rising air pollution levels in India’s urban and industrial regions, diesel generator (DG) sets have come under strict environmental scrutiny. These generators, widely used for backup power, are significant contributors to harmful emissions such as particulate matter (PM), nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC). To address this issue, the Central Pollution Control Board (CPCB) has introduced stringent emission norms and mandated the use of Retrofit Emission Control Devices (RECDs) for in-use DG sets.

What is an RECD?

A Retrofit Emission Control Device (RECD) is an after-treatment system installed on existing diesel generator sets to reduce exhaust emissions. Unlike new DG sets that are manufactured with built-in emission control technologies, older DG sets require retrofitting to meet regulatory standards. RECDs are designed to capture or convert harmful pollutants before they are released into the atmosphere.

Typically installed in the exhaust line, RECDs use a combination of filtration and catalytic processes. Ceramic filters trap particulate matter, while catalytic converters help oxidize CO and HC and reduce NOx emissions.

CPCB Norms for DG Sets

The CPCB, under the Ministry of Environment, Forest and Climate Change (MoEF&CC), has established emission standards for DG sets to control air pollution. These norms have evolved over time and are becoming increasingly stringent.

Key highlights include:

• Emission limits for pollutants such as PM, NOx, CO, HC, and smoke opacity

• Mandatory compliance for new DG sets from July 2025 onwards

• Guidelines for stack height and exhaust dispersion to minimize ground-level pollution

However, a major concern has been older DG sets manufactured before the latest emission norms. These sets often fail to meet current standards and are significant contributors to urban air pollution.

Mandatory RECD Installation

To tackle emissions from legacy DG sets, regulatory bodies such as CPCB and directives from the National Green Tribunal (NGT) have made RECD installation mandatory for certain categories of DG sets especially those in the capacity range of 125 kVA and above and manufactured between July 2004 and June 2023.

Aceget focuses on high-efficiency filtration and catalytic systems that ensure maximum particulate matter reduction while maintaining optimal engine performance. Their solutions are engineered to meet CPCB guidelines and are tested for durability, efficiency, and operational reliability.

This mandate is particularly strict in non-attainment cities and regions with poor air quality. The goal is to ensure that even older equipment operates within permissible emission limits without requiring complete replacement.

Classification and Approval of RECD

CPCB has laid down detailed procedures for testing and approving RECD technologies. Devices are categorized based on their emission control capabilities:

• Class I RECD: Designed to control particulate matter without increasing NO₂ emissions

• Class II RECD: Controls PM while maintaining NO₂ emissions within prescribed limits.

For approval, RECD systems must demonstrate a minimum level of emission reduction particularly for particulate matter and must be tested under standardized conditions. Only CPCB-approved devices are considered compliant for regulatory purposes.

Benefits of RECD Implementation

The adoption of RECD technology offers multiple benefits:

1. Significant Emission Reduction

   RECDs can reduce particulate emissions by up to 90–96%, depending on operating conditions and device efficiency.

2. Regulatory Compliance

   Installing a CPCB-approved RECD ensures adherence to environmental norms and avoids penalties or operational shutdowns.

3. Cost-Effective Solution

   Retrofitting is more economical than replacing existing DG sets with new compliant models.

4. Improved Air Quality

   By reducing harmful emissions, RECDs contribute to better ambient air quality and public health.

5. Ease of Installation

   Most RECD systems are plug-and-play and do not require major engine modifications.

Operational Considerations

For optimal performance, proper installation and maintenance of RECDs are essential. The device should be installed close to the engine exhaust to prevent clogging and ensure effective filtration. Additionally, DG sets should operate at a minimum load (typically around 35%) to maintain adequate exhaust temperature and avoid carbon buildup.

Regular monitoring of back pressure, temperature, and emissions is also necessary to ensure sustained compliance.

Challenges and Way Forward

Despite clear regulations, challenges remain in widespread RECD adoption. These include lack of awareness, cost concerns, and the presence of non-certified vendors in the market. Ensuring compliance requires not only installing RECDs but also selecting CPCB-approved technologies and maintaining proper documentation for inspections.

Going forward, stricter enforcement, technological advancements, and increased awareness will play a key role in accelerating RECD adoption across industries, commercial establishments, and residential complexes.

Conclusion

Retrofit Emission Control Devices (RECDs) represent a crucial step toward sustainable and compliant power generation in India. As CPCB norms become more stringent, retrofitting existing DG sets is no longer optional but a regulatory necessity. By significantly reducing emissions and enabling compliance, RECDs help bridge the gap between environmental responsibility and operational continuity paving the way for cleaner air and a greener future.

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