Cogeneration and Trigeneration’s role in the transition from fossil fuels to renewables

Denilson Boschiero do Espirito Santo's picture
Denilson Boschiero do Espirito Santo, Technical and Commercial Director, Sisterm Thermal Systems
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Despite the conundrum of natural gas’ ‘role to play’ in a decarbonised society, natural gas projects, including LNG, continue to be implemented in many developed and developing countries, revealing unsolved challenges in the migration process.

The transition from fossil fuels to renewables needs to be done by looking to extract the most mature existing fossil fuel technologies while surpassing the challenges behind renewables bigger share in the energy sector (grid instability due to intermittence); as well as the implementation of others technologies that needs to be integrated in a stable smart grid (hydrogen, batteries, peak loads thermal plants, etc).

Engine cogeneration and trigeneration systems have a higher contribution to this transition. Recent studies utilising the ETE (equivalent thermal efficiency) criteria reveals that well-designed engine cog/trigeneration systems can be compared with 50-80% centralised thermal plants. Well-designed systems mean that engine cog/trigeneration systems are able to operate with high efficiency throughout most of the year. Predicting performance, however, needs the site energy consumption analysis.

Sisterm Thermal Systems is releasing an engine cog/trigeneration system design and simulation software (COGMCI) able to develop the design of high-efficiency systems and annual energy analysis prediction. Energy balance and simulation methods are used in the COGMCI software.

COGMCI software allows the use of real engine performance data integrated with HRSG (heat recovery steam generators), exhaust gas heat exchangers, absorption chillers, heat exchangers, cooling towers, air coolers, etc. Economic analysis has also been developed.

Different operational strategies can be stimulated:

  • Full load
  • Electrical dispatch
  • Thermal dispatch

Engine cog/trigeneration systems can be planned to operate in the base of the electric loads or to export electricity.

Detailed analysis developed with the COGMCI software reveals that at electrical and thermal dispatch mode, the engine cog/trigeneration system can operate at part load when renewables (solar and wind) face high electricity production hours, and with the engine at full load (exporting electricity) at the hours renewables faces reduced electricity production – avoiding batteries and low-efficiency peak loads thermal plants.

Oversized engine cog/trigeneration systems benefit from higher engine efficiency (bigger engines normally have higher thermal efficiency) while still recovering residual energy for steam, hot water and chilled water production.

High-efficiency engine cog/trigeneration systems have a better role to play in the transition scenario, with several possibilities to be explored. Policymakers can use the software to define incentives and raise the country average thermal efficiency. Higher average thermal efficiency means lower NG use/import, dependence and reduced environmental impacts.

A demo version of the COGMCI software can be viewed here.

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