Commentary on the scientific journal «Russian Gas Society».
We always follow the latest developments and changes in our industry as well as interesting expert opinions and news publications. We want to note that the article "Methane–hydrogen mixtures as an environmentally friendly alternative fuel" was published in the Scientific Journal of the Russian Gas Society, 2022, No. 2 (34), pp. 76–94. You can find the full article here: https://gazo.ru/ru/media/publications/nauchnyy-zhurnal-rgo-2-2022/.
We asked Chief Technologist at ANO «Hydrogen Technological Solutions», Candidate of Technical Sciences, B.A. Rybakov, to comment on this article from a professional perspective for our readers.
Dear readers, please find below detailed comments from B.A Rybakov.
In my opinion, using methane–hydrogen mixture (MHS) in transport and energy has great potential.
The article "Methane-Hydrogen Mixtures as an Alternative Environmentally Friendly Fuel" is divided into five main parts:
- Fuel Characteristics of Methane-Hydrogen Mixtures
- The Use of Methane-Hydrogen in Engines
- Technical and Emission Characteristics of Engines Powered by Methane-Hydrogen
- Transportation of Methane-Hydrogen by Pipeline
- Risksand Safety Measures for the Use and Transportation of MHS
Quote №1.
In the second section, «The Use of MHS in Engines» it is mentioned that:
In the same section a brief description of adiabatic methane conversion (AMC) technology for production of MHS with hydrogen content up to 48 % is given.
Quote №2.
Comment:
This article discusses the advantages of AMC technology, but it does not mention any disadvantages of this technology.
Some of the main disadvantages are:
- The need for steam, which requires water for production
- Formation of carbon dioxide during methane conversion into hydrogen
It would be beneficial to consider these when discussing methane–hydrogen mixture (MHS) production, in light of the section on «Problems of Transporting Methane-Hydrogen Mixtures by Pipeline Transport».
To obtain permission to transport gas through Russian pipelines, the gas must comply with GAZPROM 089-2010 standards, which specify the requirements for NGP in terms of physical and chemical properties.
The dew point temperature of water is not higher than -10°C in temperate areas, and -20°C for cold areas.
The dew point for hydrocarbons in temperate regions is not lower than -2°C in winter and -5°C in summer.
In cold areas, it is -10°C during winter and -15°C during summer under standard conditions.
Low heat of combustion under standard conditions - not less than 31.8 MJ/m3.
Molar fraction of carbon dioxide - not more than 2.5%.
In gas condensate fields, natural gas is usually drained before being injected into a pipeline to meet the maximum dew point requirement for water. If the dew point value exceeds during transportation, water condensate will fall out and cause corrosion of the pipeline.
As mentioned above, the technology for producing MHS using the AMC method involves adding water vapor to natural gas, which leads to the humidification of MHS. Therefore, before pumping this gas into the pipeline, it needs to be drained.
Mixing hydrogen with natural gas decreases the volumetric heat value of the latter's lower heat of combustion. Therefore, limiting the specific reference temperature (SRT) of the lowest calorific value to 31.8 MJ/m³ automatically leads to limiting the maximum concentration of hydrogen in MHS.
Typically, the lowest heat value of pipeline gas in Russia ranges from 34 to 35 MJ/m³.
Calculations show that in order to meet the condition of limiting the lowest combustion heat of gas, the volumetric concentration of hydrogen in MHS should not exceed 13–15%.
The presence of carbon dioxide in natural gas decreases its heat of combustion. This is why, in Standard 89-2010, there is a restriction on the concentration of CO2. Therefore, before being injected into the gas pipeline of MHS, which is obtained using the AMC method, the mixture needs to be cleaned of carbon dioxide.
This does not diminish the scientific value of the article in any way.