# Boiler heat recovery: Impact and additionality

Saving fuel, water and chemicals in one move

Source page: https://www.materialinsights.org/energy/e_boiler_recovery/rc-impact/

What this tab covers The impact and additionality lens: direct emission cuts, side benefits for water and air, and the risk of prolonging the life of a polluting host plant.

Each measure cuts on-site fuel burn directly, and condensate and blowdown recovery also save water and treatment chemicals.

#### Direct Scope 1 and Scope 2 abatement
Favourable

DOE's economiser example recovers about 38,600 MMBtu of heat a year; at 80% boiler efficiency that is about 48,300 MMBtu of gas, or roughly 2,560 t CO2 a year at 0.0053 t CO2 per therm (calculated). The blowdown example saves 8,500 MMBtu a year, about 450 t CO2 (calculated). Skyven's California Dairies projects had avoided over 3,500 t CO2 and over 65,000 MMBtu of gas by early 2024, with over 7,000 t a year projected.^[1](https://www.energy.gov/sites/prod/files/2014/05/f16/steam3_recovery.pdf)^[3](https://www.energy.gov/sites/prod/files/2014/05/f16/steam10_boiler_blowdown.pdf)^[8](https://www.aceee.org/sites/default/files/pdfs/ssi21/panel-3/Zahlan.pdf)^[9](https://betterbuildingssolutioncenter.energy.gov/implementation-models/skyven-technologies-decarbonizing-industrial-process-heat-public-private)
 CO2 avoided, DOE economiser example about 2,560 t/yr (calculated)^[1](https://www.energy.gov/sites/prod/files/2014/05/f16/steam3_recovery.pdf)^[8](https://www.aceee.org/sites/default/files/pdfs/ssi21/panel-3/Zahlan.pdf) CO2 avoided, DOE blowdown example about 450 t/yr (calculated)^[3](https://www.energy.gov/sites/prod/files/2014/05/f16/steam10_boiler_blowdown.pdf)^[8](https://www.aceee.org/sites/default/files/pdfs/ssi21/panel-3/Zahlan.pdf) California Dairies projected abatement over 7,000 t CO2 a year^[9](https://betterbuildingssolutioncenter.energy.gov/implementation-models/skyven-technologies-decarbonizing-industrial-process-heat-public-private)

#### Water and air synergy
Favourable

Returning condensate cuts makeup water, sewage and treatment chemicals: a US specialty paper plant cut makeup water from about 35% of steam output to 14 to 20% and saved over USD 300,000 a year. Reducing blowdown from 8% to 6% on a 45 t/h (100,000 lb/h) boiler saves about 1 t/h (2,300 lb/h) of makeup water. Condensing units also pull water out of flue gas (about 85% of the humidity for direct-contact and 35% for indirect designs), though this water is acidic.^[5](https://www.energy.gov/sites/prod/files/2014/05/f16/steam8_boiler.pdf)^[2](https://www.energy.gov/sites/prod/files/2014/05/f16/steam26b_condensing.pdf)^[4](https://nrel.gov/docs/fy12osti/52761.pdf)
 Paper plant makeup water from about 35% to 14 to 20% of steam^[5](https://www.energy.gov/sites/prod/files/2014/05/f16/steam8_boiler.pdf) Flue gas humidity removed, direct-contact about 85%^[2](https://www.energy.gov/sites/prod/files/2014/05/f16/steam26b_condensing.pdf) Makeup water saved, 8% to 6% blowdown about 2,300 lb/h on a 100,000 lb/h boiler^[4](https://nrel.gov/docs/fy12osti/52761.pdf)

#### Avoided lock-in
Mixed

Economisers and condensing units make existing gas or coal boilers cheaper to run and can delay a switch to heat pumps or electric boilers. The capital is small, though, and condensate return and blowdown recovery reduce heat demand whatever the future heat source, so they are no-regret. Investors should favour these water-side measures and treat flue-side upgrades on coal boilers with more caution.^[5](https://www.energy.gov/sites/prod/files/2014/05/f16/steam8_boiler.pdf)
 Share of steam energy left in condensate more than 10%^[5](https://www.energy.gov/sites/prod/files/2014/05/f16/steam8_boiler.pdf)

#### Sources

1. [Use Feedwater Economizers for Waste Heat Recovery, Steam Tip Sheet #3 (DOE/GO-102012-3412)](https://www.energy.gov/sites/prod/files/2014/05/f16/steam3_recovery.pdf) US DOE Advanced Manufacturing Office, 2012
2. [Considerations When Selecting a Condensing Economizer, Steam Tip Sheet #26B (DOE/GO-102012-3397)](https://www.energy.gov/sites/prod/files/2014/05/f16/steam26b_condensing.pdf) US DOE Advanced Manufacturing Office, 2012
3. [Recover Heat from Boiler Blowdown, Steam Tip Sheet #10 (DOE/GO-102012-3408)](https://www.energy.gov/sites/prod/files/2014/05/f16/steam10_boiler_blowdown.pdf) US DOE Advanced Manufacturing Office, 2012
4. [Install an Automatic Blowdown-Control System, Steam Tip Sheet #23 (DOE/GO-102012-3402)](https://nrel.gov/docs/fy12osti/52761.pdf) US DOE Advanced Manufacturing Office, 2012
5. [Return Condensate to the Boiler, Steam Tip Sheet #8 (DOE/GO-102012-3410)](https://www.energy.gov/sites/prod/files/2014/05/f16/steam8_boiler.pdf) US DOE Advanced Manufacturing Office, 2012
6. [Not Just Hot Air: Low-Cost Decarbonization through Heat Recovery (Zahlan and Talan, Cadmus), ACEEE Summer Study on Energy Efficiency in Industry](https://www.aceee.org/sites/default/files/pdfs/ssi21/panel-3/Zahlan.pdf) ACEEE, 2021
7. [Skyven Technologies: Decarbonizing Industrial Process Heat through Public-Private Partnerships (implementation model)](https://betterbuildingssolutioncenter.energy.gov/implementation-models/skyven-technologies-decarbonizing-industrial-process-heat-public-private) US DOE Better Buildings Solution Center, 2024

## Other sections

- [Summary](https://www.materialinsights.org/energy/e_boiler_recovery/index.md)
- [Overview](https://www.materialinsights.org/energy/e_boiler_recovery/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_boiler_recovery/correlation/index.md)
- [Science and thermodynamics](https://www.materialinsights.org/energy/e_boiler_recovery/rc-sci/index.md)
- [Engineering and integration](https://www.materialinsights.org/energy/e_boiler_recovery/rc-eng/index.md)
- [Economics and contracts](https://www.materialinsights.org/energy/e_boiler_recovery/rc-econ/index.md)
- [What to track](https://www.materialinsights.org/energy/e_boiler_recovery/tracking/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_boiler_recovery/links/index.md)