The transition of distribution system operators towards sustainability


What are the implications of the introduction of sustainable gases for distribution system operators?

Anton Janssen at Kiwa Technology in Apeldoorn on 4 December 2014 (photo: Kiwa/Harald Hopoff) Anton Janssen at Kiwa Technology in Apeldoorn on 4 December 2014 (photo: Kiwa/Harald Hopoff)

Sustainable gases have different quality than the current natural gas transported and distributed in the Netherlands. Before injecting these gases, distribution system operators will have to adapt their infrastructure and operations. Several researches on this topic had been presented at a seminar at Kiwa Technology in Apeldoorn on 4 December. Presentations were made on the technical and economic aspects of the question.

The impact on the infrastructure

The impact of biogas on physical materials of the gas infrastructure remains largely unknown. René Hermkens and his team have identified which material component can be affected by biogas. To fill the gap in the literature, they have carried laboratory experiments inside a facility but also outside in order to stimulate real operation conditions of materials laid in the underground.

Testing the impact of biogas on metals, they have found that water remains by large and far the component that affect the most materials. Pipes and joints made out of corrosive metals have higher rate of degradation when exposed to biogas. Besides, they have found that biogas, when present at high concentration, contribute to the deterioration of rubber materials.

Biogas will also have an impact on end-user equipment. Hans de Laat reported the results of experiments on the injection of biogas in motors. “Behaviour of gas engines may be critical with the arrival of new gases from LNG, high calorific gas and sustainable sources,” he said. Experiments identified engine knock as the central problem created by new gases. Engine knock happens when the combustion of gas in the cylinder does not occur at the optimum moment.

Besides, De Laat and his team have tested combustion of gases on domestic appliances. They tested appliances sold on markets by manufacturers and currently in use in households. They found out that a maximum of ten percent of hydrogen can be mixed up to gas without creating a problem. A higher concentration of hydrogen represents a risk for some types of appliances. 

Risks and security issues

Biogas contains chemical compounds that becomes toxic at high concentration. Hydrogen sulfite, for example, poses a risks, but it can be detected portable meters to protect workers. Should distribution system operators change the safety and security codes they already apply for natural gas? Michiel van der Laan and his colleagues have carried original experiments. They found that leak of biogas from pipelines in the underground can be detected at the same concentration as natural gas. Moreover, they found that the dispersion of biogas around worker in the air is very similar to natural gas.

Biogas will be produced and stored at decentralized location. Johannes de Bruin and his team have analyzed the security risks that this technology poses. They have considered the technical specifications as well as the social and legal constraints. One of the conclusion is that biogas can be treated as natural gas as for the control and mitigation of hazard such as fire, explosion, leakage, etc.  

Biogas contains detrimental trace components such as siloxanes and terpenes. Yet, up until now, there was no reliable method to measure the concentration of these components in biomethane. Eric Polman reported the development of measurement methods that are not only reproducible but that can provide stable references. They can serve as a firm basis in the formulation of standards for the measurement of siloxanes and terpenes. 

Management and economic aspects

Distribution system operators will face complex investment decisions in adapting the gas infrastructure for sustainable gases. While investing in pipes, storage and compression stations, they want to optimize their investments but by keeping the assets flexible as much as possible. Computer models can help them in analyzing real investment options and help them in making wise investment choices, according to Cees Pulles.

Besides modelling, distribution system operators can rely on scenarios to anticipate possible evolutions of the gas market and the corresponding requirements for the infrastructure. A least four scenarios are foreseen for the Dutch gas distribution system by 2050, according to Pulles. These are the scenarios of business as usual, market constraint, tight market and renewable self-efficiency.

“How to contribute to a sustainable low-carbon infrastructure by combining gas, electricity and heat?” asked Hans de Laat. Experiments have been carried at Kiwa Technology’s laboratories to generate data on energy converters. De Laat and his team have studied industrial boilers, cogeneration units, chargers of electric vehicles and power routers for households. 

By Jean-François Auger