Biogas is gas that is produced from renewable sources, such as organic waste, manure or sewage sludge. Biogas can be used for three purposes:
- for electricity and heat production;
- it can be upgraded to Bio CNG;
- it can be fed into the gas network as green gas.
The latter two cases involve green gas.
The term green gas is used to indicate that it is biogas that has been upgraded to natural gas quality. Just as for green electricity, there is a certification system for green gas. Vertogas is responsible for this, an independent institute mandated by the Ministry of Economic Affairs. Vertogas certificates prove that the green gas is produced from biomass and that it has the same quality as natural gas. The certificate is the so-called 'Guarantee of Origin' (in Dutch: GVO). One Vertogas certificate stands for 1 MWh of energy from green gas, which is comparable to approximately 100 cubic meters of natural gas.
In the event that the green gas is not fed into the national gas network, the GVOs that Vertogas provides are recognizable as 'GVO non-grid supply'. These 'GVOs non-grid supply' therefore have a fixed destination and are not freely tradable. As soon as green gas is fed into the gas network, it is no longer recognizable as green gas because it mixes with natural gas in the transport pipe. The gas is traded as normal fossil gas and transported to users. The green attribute has been transferred to the certificate and can then be traded separately from the physical gas flow and reconnected to the physical gas flow if an end user consumes the green gas. As a result, anyone who wishes to buy green gas without being physically connected to a green gas producer can still make their energy consumption more sustainable. Just as with electricity, there are therefore two markets: a physical gas market (gas trade) and a virtual certificate market (certificate trade). An end user can indicate to his supplier that he wants to buy green gas in order to green his gas use. Your supplier or certificate dealer will have to buy and deduct green gas certificates for this. Individual certificates can only be purchased by traders. The writing off of certificates for use (sale of green gas to an end consumer) is mandatory.
Driving on green gas
It is also possible to drive on green gas in the form of Bio CNG (Compressed Natural Gas). It is an alternative to driving on natural gas (CNG). It is possible that the gas station where you refuel your natural gas offers you that option with certificates. It is also possible to purchase certificates separately to run your company fleet on green gas. For this you can contact a dealer or supplier. The registration of the certificates is done via an account of the Dutch Emission Authority (in Dutch: NEA) within the Vertogas system.
CO2 emission factors for green gas
Since 2019, every green gas certificate from Vertogas with an NTA8080 or ISCC quality mark has a verified emission factor stated in gr. CO2/MJ. If this factor is missing, the most accurate CO2 emission factor from the website www.co2emissiefactor.nl should be used for green gas. The website distinguishes four types of emission factors for green gas:
- Green gas (landfill gas)
- Green gas (co-fermentation)
- Green gas (GFT fermentation)
- Green gas (sewage sludge)
In addition, an emission factor with an average value is stated, which is explicitly not intended for individual emission calculations. It is clearly demonstrable at the GVO from which source the green gas comes, so which emission factor should be used.
There are providers who offer 'green gas' through CO2 compensation. This goes beyond the Vertogas system. The relevant providers buy so-called carbon credits for this on the international market. There are several reliable standards for this: the Clean Development Mechanism, which is part of the international Climate Treaty, the Gold Standard and the Voluntary Carbon Standard. CO₂ compensation measures fall outside the measuring range of the CO₂ Performance Ladder. Compensation measures therefore do not contribute to achieving a (higher) level on the CO₂ Performance Ladder. Compensated gas therefore does not count as green gas for the CO2 Performance Ladder.
NB: the CO₂ Performance Ladder does not, however, make any statement about the social relevance of such measures.