The latest 'Topic Oriented Technical Meeting' (TOTeM), number 45 in a series that started back in 1989, was held in Cardiff on 3-4 September on 'Gas turbines for future energy systems'.
With gas (combustion) turbines accounting for around 23% of global electricity generation and year-on-year growth of generation from gas looking to continue into the future (particularly in distributed energy generation and cross-sector application, ie power, propulsion and mechanical power), the role of GTs in energy systems - and how these will complement the rapidly increasing generation from renewables (particularly from intermittent wind and PV) - was a highly relevant topic for an IFRF TOTeM…
However, GTs will need to meet a number of 21st century challenges, namely:
- To be able to produce flexible power (both operationally and in terms of fuels flexibility).
- To be a companion to renewable generation.
- To fulfil the increasing need for cost-effective energy vectors in responsive energy storage solutions (so-called 'storage-to-power').
- To enable a move to decarbonised power (through greater efficiency, exhaust gas recirculation/recycling, carbon capture, and moving towards hydrogen energy).
- To have ever higher reliability, availability and maintainability; at lower cost (both in terms of capital cost and operational costs); all achieved with a greater safety of operation.
No mean feat!
In this context, an eager and distinguished group of 35 gas turbine (GT) practitioners, manufacturing industry representatives, system developers, experts and researchers met for two days of lively and interactive presentations and discussions, and a site visit to Cardiff University's Gas Turbine Research Centre at Port Talbot and the Baglan Hydrogen R&D Centre. A fun evening was also spent enjoying 'all things Welsh' at Cardiff Castle.
Thanks are also due to our partners and sponsors for this fascinating meeting - GTRC, FLEXIS, APGTF, the Fossil Energy Research Forum and Infosys.
Below is an initial read-out of the key messages from TOTeM45:
Context
- Global growth of gas-fired power generation as complement to renewables.
- 23% of global 25,600 TWh from gas, 1.6% increase in 2017 (7.6% decrease in USA counterbalanced by 4.6% growth in rest of world - particularly China, EU, SE Asia).
- So why reluctance for GT research support?
- Challenges in terms of flexibility, transient response, etc.
- Currently no real driver for carbon capture storage (CCS) on GTs from industry - carbon price too low, financial case?
- Combustion dynamics (CD) are a significant issue.
- Dual-fuel (liquid/gas) flexible systems also required.
- Different methods (eg axial) for 'staged' combustors, with strengths/weaknesses.
- Different industrial staging designs, eg EV Burner (Alstom) , SWOZZLE (GE).
- Swirl, vortex breakdown integral.
- GT cycles increasing temperature for efficiency -> increased NOx?
- Near-term R&D priorities: Additive manufacture; model-based control (sensors, artificial intelligence, 'big data'); enhanced prediction of CD.
GTs for flexible power (operational and fuels flexibility)
- How far can we get with simplified lower-order network model + flame describing function (FDF) models for CD?
- Validation: Encouraging/surprising! (EM2C, Camb, Siemens…) to date -> more experimental (optical) validation required
- Predictability sufficient for industry purposes?
- How to calculate FDFs 'accurately enough'?
- Four-step chemistry sufficient (for industry?) - to be confirmed.
- Active/feedback control? Response time?
- New fuels (H2, NH3) will also suffer from CD.
- Plea for industry to vocally support research funding applications in the field.
- Problems in predicting CD, even when Wobbe Index (WI) is 'in spec', C2+?) ->
- Additional combustion /fuel parameters required. What? Methane number?
- OEMs have developed control systems but they are expensive - cheaper options?
- Heading towards >20% H2 in gas grids. Issues?
- New burners are now designed to avoid flashback.
- 'Permutation entropy' for predicting CD onset - 1s response.
- Other 'relatively cheap' techniques, including laser-induced breakdown spectroscopy (LIBS) and chemiluminescence (CL), being developed for non-intrusive burner diagnostics - how much optical access practicable?
GTs for 'storage-to-power'
- H2 in gas system variety of sources (syngas/CCS, green H2…).
- Changes required in combustion; materials/cooling; turbo.
- WI variation insufficient: what in addition?
- New combustion systems required for high-H2 fuels?
- Promising 'FLOX' (flameless combustion) system claimed capable of burning H2 with high fuel/operational flexibility and low emissions.
- What is and what isn't FLOX?
- Staged combustion autoignition showed operational window for high-H2 operation.
- H2 energy transportation -> case for ammonia (NH3)?
- Established challenges for NH3: economics, NH3 emissions, NOx, public acceptance.
- Various methods for reducing NOx recently demonstrated in Wales and Japan (RQL, humidified, operational pressures).
- Existing research tools enable ammonia combustion optimisation. Needs funding to keep UK competitive.
GTs for safe, decarbonised power
- Exhaust gas recirculation (EGR) required for post-combustion CO2 capture on GTs.
- O2 will limit the degree of EGR achievable.
- Oxyfuel CCS GT promising but need turbomachinery and combustor developments.
- Oxyfuel with first generation burners shows good stability, but lots of challenges for development, eg CO emissions.
- Various ways of adapting GT operation for improving CCS efficiency. But what is the optimum combination?
- Advanced solvents for post-combustion capture.
- System integration and whole systems analysis required.
- Social science, public perception, risk/safety for CCS.
- H2 safety still requires attention: ignition, DDT potential…
- How best to mitigate scenarios like flame-out, H2 jet in hot environment.
- Are H2 explosion/detonation scaling sufficient? Geometries?
Additive manufacturing and advanced materials
- Considerable GT materials info, but often poorly characterised experimentally.
- 'Open Access' materials database proposed (by ETN?): IFRF should link and promote.
- Higher operating conditions… -> materials development needs.
- Additive layer manufacturing (ALM) is a potential 'game changer'.
- ALM has key role for GTs in terms of enabling better thermal management and lightweighting.
- Most OEMS have active ALM programmes.
- ALM gives potential to design and manufacture high-temperature components which couldn't be delivered with traditional techniques.
- Enables reduction of materials utilised and significant incremental efficiency improvement mitigates/eliminates cost differential with traditional techniques.
- Several examples of components built for high-end markets (eg F1, etc) from likes of HEITA (eg LT and HT HEXs, turbomachinery, fuel and combustion components).
- Up to 50% weight reduction achieved. Metal temperatures reduced by up to 220°C, enabling turbines to run hotter.
- Could there be a role as proposed collective database for ALM future development?
- Expect to see considerable development in this field, challenges include surface finishing.