In several recently published Monday Night Mails and Industrial Combustion journal papers, we have highlighted the changes in the quality of gaseous fuels that are occurring – and are likely to occur increasingly – in many countries.
As a wider range of more diverse gaseous fuels become available or are utilised by industry (i.e. not just ‘traditional’ natural gas, but increasingly LNGs from a range of sources, shale gas(es), biomethane, hydrogen blends, bioSNG from wastes, and higher-content/pure hydrogen, etc.), so more R&D is required to consider the impacts of these differing fuels in industrial, power generation, commercial and residential applications. These impacts include effects on the operation of fired equipment, effects on the flexibility of systems, and, of course, the health and safety aspects for those working with such fuels.
The ‘quality’ of gaseous fuels in particular countries varies to a considerable extent, and is generally controlled by either regulations or standards that stipulate certain parameters, or maxima/minima/ranges of certain constituents or physical properties. In terms of the composition of gases, the content of H2S, total S, H2, O2 and impurities are often specified, and for gas parameters, the H2/H20 dewpoints, the Wobbe Number/Index (or calorific value or relative density or some combination), the Sooting Index and the Incomplete Combustion Factor (or carbon-in-ash or loss-of-ignition) are often specified.
It is widely recognised that in order to accommodate the use of a wider range of gas qualities in society, the varying regulations and/or standards in place in many jurisdictions will need to be adjusted intelligently over time, and this will undoubtedly necessitate R&D to allow such modifications to be made with confidence concerning the impacts and at acceptable costs of implementation.
In the UK, the Institution of Gas Engineers and Managers (IGEM) have instigated a process for developing a new Industry Standard to replace the current Gas Safety (Management) Regulations 1996 (GSMR): It is considered that a Standard will be easier to establish and modify than regulations and will support safe practice without necessitating prescriptive regulation. To drive this initiative forward in the UK, IGEM established a Gas Quality Standards Working Group in June 2016, and have produced (after ten meetings) a first working draft ‘IGEM Standard for Gas Quality’ and commissioned some research relevant to the industrial and commercial sectors.
Building on a recent stakeholder consultation exercise undertaken by consultants DNV GL and involving organisations across the ‘gas chain’, a workshop was held at IGEM’s HQ last week. IFRF’s Director, Philip Sharman, was invited to participate in this workshop.
After an introduction from Ian McClusky of IGEM and after some background to previous work from Gus McIntosh of SGN, Sarah Kimpton of DNV GL described the challenges associated with gas quality variations. From the ‘Mean Bacton Gas’ (i.e. a specification considered representative of all UK North Sea gas(es)), through the development of the GSMR, to the increasingly diverse gaseous fuels of the future, the thinking on gas quality requirements for the UK has changed considerably (and indeed gas quality specs vary considerably from country to country across Europe). Sarah outlined the existing GSMR requirements and illustrated the particular challenges of hydrogen compared with methane (similar Wobbe Index despite very different CV and RD, differing velocity of sound in the respective gases, and radically different Joule-Thompson Effect and flame speed).
Martin Brown of DNV GL examined the particular industrial and commercial challenges related to gas quality limits and fluctuations, focusing on the increasing flexibility needs of Network Operators and users, and the fundamental impacts of gas quality on combustion, and the possible impacts of wider range of gas quality on equipment used in the industrial and commercial sectors. He highlighted the purpose of this current initiative – i.e.: to look at expanding the UK’s Wobbe Index range (GSMR currently regulating this to 47.20 – 51.41MJ/m3, i.e. a range of around 4.2MJ/m3) initially by increasing the Upper Wobbe Index Limit (from 51.41MJ/m3 to 53.25MJ/m3) and subsequently decreasing the Lower Wobbe Index Limit (from 47.20MJ/m3 to 45.67MJ/m3); and extending the allowable content of hydrogen from ≤0.1mol% up to a limit of 20mol% in the blend – before going on the identify the range of stakeholders across the ‘gas chain’ that DNV GL had engaged with in their questionnaire and face-to-face meetings. The workshop was aiming to explore the responses further and begin to develop a roadmap of priority R&D issues and a timescale to implementing the IGEM Gas Quality Standard.
The workshop participants were divided into a number of break-out groups, initially looking at the results of questionnaire respondents by industry segment (i.e. gas engine/turbine OEMs and users; industrial applications and control systems; burners and boilers – notably in relation to the glass/ceramics sectors and their emissions; government, regulatory, trade associations and gas transporter stakeholders; and gas storage and chemical feedstock applications). It was fascinating to note the differences in the perceived impacts of these ‘sectors’/applications/stakeholders, as well as wide variation in the level of knowledge concerning potential impacts. A second session of break-out groups looked at the critical areas of barriers/challenges and the impacts of potential solutions, and trying to identify priority research topics and roadmaps/timescales for progressing these.
A number of common themes emerged from the groups, as well as a recognition of the complexities of taking forward both aspects of the project (i.e. extending the Wobbe Index Range and the allowable hydrogen content in gaseous fuels). A progressive programme/timescale for extending the Wobbe Limits was discussed, as well as possibly ‘de-coupling’ the two different objectives (the proposed extension of Wobbe Limits being considered by the participants to be a much simpler challenge than the hydrogen limit consideration.
IGEM’s Working Group, with support from DNV GL, will be considering all these outputs from the questionnaire, the face-to-face interviews and the workshop in developing the next stage of this important initiative.
Overall a worthwhile and very well organised workshop on an important area for the future of gaseous fuel in the UK.
On a final note, Philip shared his thoughts on Twitter during the course of the workshop and we’ve turned his various tweets into a Twitter Moment for you to look back on. Click here to view this Twitter Moment.