Main impact: Novel technology for combustion of 100% H2 in gas turbines, allowing large-scale emission free power generation at high efficiency (>60%)

Gas Turbine from Ansaldo, GT36.
Gas Turbine from Ansaldo, GT36.

The challenge

Hydrogen can be used for clean and highly efficient power generation with minimal CO2 footprint. Improved fuel flexibility of gas turbine combustion system is desirable, e.g. combustion of 100% H2 without the need of fuel diluents as N2 or steam injection. Known challenges for H2  combustion are:

  • Flashback (off-design flame displacement): higher risk due to higher flame speed
  • Autoignition (off-design early ignition): higher risk due to lower ignition delay time
  • Combustion dynamics (thermo-acoustic instabilities): well-known thermo-acoustic amplitude level and frequencies for natural gas combustion are modified by hydrogen addition
  • NOx emissions: due to higher flame reactivity, temperature and different structure/stabilization.

The innovation

Combustion technology development leads to potentially novel solutions to allow retrofit of existing gas turbines for combustion of 100% H2:

  • H2-rich fuel injection system design
  • Combustion chamber design
  • Expertise in H2 combustion control

Potential impact

  • Efficient large-scale power generation based on H2 from natural gas with CCS
  • Compared to available technology the research aims to enable combustion of 100% H2, saving fuel costs by not needing diluents as N2, usually at a ratio of 10kg N2 per kg H2 to be combusted.
  • Hence, achievement of carbon-free power generation that is both clean (low NOx) and thermodynamically efficient (>60%), at large scale (>1000 MW).
  • Bridge H2 production from natural gas w/CCS and H2 from renewable sources, at large scale.

Base case for illustration: Baseline NG-fired CCGT: 750 MWe @ 60% efficiency. Key assumptions:

  • 10 kg N2 pr kg H2 are the dilution requirements in conventional non-premixed systems (overall plant efficiency loss 4%)
  • Firing temperature reduction in premixed systems with advanced staging (sequential/reheat) results in 1% overall plant efficiency loss
  • H2 cost is 1,5 Euro/kg and cumulative yearly energy production target is 6.24 TWh

Reduced fuel costs are related to savings due to higher overall plant efficiency for the dilution-free advanced staging combustion system and estimated to 39 MEur/year. The cumulative yearly H2 fuel cost for conventional N2-diluted H2 combustion system is 544 M€, while the cumulative yearly H2 fuel cost for pure H2 combustion system with advanced staging is 505 M€.

There will be considerable additional savings because of unnecessary process equipment for diluent (nitrogen or steam) preparation and reduced emissions as the CO2 avoided, if H2 is produced without CO2 emissions, of 2.1 Mt/year.