Gas networks in NW Europe (but not the UK) are generally divided into L-gas (low calorific gas) and H-gas (high calorific gas). The dependence on one large field for L-gas is becoming apparent, and with this field facing production restrictions, problems may occur before the L-gas networks can be converted into H-gas networks. Using H-gas in L-gas networks is unsafe, and many domestic/commercial appliances can only work with a certain range of gas.
What is the difference between H-gas and L-gas?
To understand this, it’s important to know that the calorific value of a fuel is the amount of heat released in a consistent setting (perfect combustion, pressure constant, etc.). This is usually translated, for gas, into the Wobbe Index, which is the ratio of the calorific value and the square root of relative density determined at an identical measurement reference condition. To put it simply, the higher the Wobbe index, the more energy dense the fuel is.
L-gas has a lower Wobbe index as it has more inert gas (such as nitrogen/carbon dioxide) mixed in which essentially means it has less energy output for a given volume. It also means the gas has different safety requirements than H-gas, and the two would have separate and non-interchangeable infrastructure to prevent safety or technical issues.
H-gas has a higher Wobbe index as it is more pure and gives out more energy for a given volume. When gas is liquefied it is removed of many impurities, and the more inert gases evaporate over time during transit, which is why LNG has the highest Wobbe index of most gases, and impurities have to be added before it can be injected into the gas network.
As LNG is at the top of the range, it would be difficult to replace L-gas with LNG. You can see some of the different ranges of gas in the infographic below:
How did NW Europe become so dependent?
Whilst there are a range of L-gas sources in Europe such as pockets in Western Poland, or biogas production, the majority of L-gas has historically come from the Netherlands.
In the 1930s a subsidiary of Shell acquired exclusive exploration rights for oil and gas in the North-East of the Netherlands. This subsidiary then established the ‘Nederlandse Aardolie Maatschappij’ (NAM) with the Standard Oil Company of New Jersey (later to become Exxon). Though the NAM primarily aimed at oil exploration and production, gas was found first in 1948 along with a number of both oil and gas small to moderate fields in the 1950s.
Gas use in Europe was essentially galvanised by the discovery of the incredibly large Groningen gas field in the Netherlands. In 1959 NAM discovered a large gas field in the Netherlands. By the time NAM started negotiations for extraction in 1960, the field size was estimated to be 60bcm – an extremely large volume for that time. The exact size of the monolithic gas field, named Groningen, would be finally confirmed some thirty years later at 2,600bcm. Out of that figure, around 2,000bcm has been extracted.
From about 2010-2015, Groningen was producing just under 50bcm/year on average. For reference, this would be roughly equivalent to the gas demand of a country moderately smaller than the UK. However, the region where the massive Groningen gas field was located faced earthquakes and disturbing seismic activity. The Dutch government progressively introduced caps that drastically reduced production, due to safety concerns.
The potential of alternative fuels
Biogas and hydrogen both mix lower than L-gas even, and if you mix that with ‘standard’ LNG or natural gas it could theoretically balance out.
However, gases are not always interchangeable. It would take resources to consider and potentially correct for a few factors other than calorific value/Wobbe. I don’t have an engineering or scientific background on gas so do take this with a pinch of salt, but I believe these would be:
- Thermal load: how the gas flows e.g. through your pipes to your gas stove cooker.
- Backfiring: the likelihood of a gas to burn away from the direction it exits.
- Impure burning: characterised by a yellow rather than a blue flame, this means there are impurities in the mix that could be harmful or cause degradation in appliances/pipes etc.
Additionally, biogas and hydrogen projects typically take a while to set up – especially as they require government subsidy. The decline of L-gas flexibility in the region has already been priced in, so this is unlikely to cause an unexpected or sudden surge in biogas and hydrogen output.
Groningen’s decline has been known about for a long time; it was planned and has been priced into gas prices a while ago. The Dutch government’s first course of action was to start convincing large industrial users to switch away from L-gas to other fuels. Neighbouring countries have followed this action too.
Within the Netherlands, the same companies and institutions that sought to introduce Groningen gas into people’s homes are helping consumers find alternative supplies. The Dutch are firstly encouraging large industrial users to find new sources, but they are also building capacity to convert H-gas to L-gas (blending in ‘inert’ gases such as nitrogen so that gas with a slightly higher calorific value than Groningen gas such as Russian or Norwegian gas can be used in L-gas networks). They are also converting L-gas networks to H-gas. Germany, France, and Belgium are also undertaking similar projects. You can find out the details in ENTSO-G’s network development plan.