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Results at halfway of the program

2013-05-15

The research program of the Energy Delta Gas Research, arrived at halfway of its execution, delivers tangible results 

Two researchers discuss a poster on gas research during the Fifth Research Day on 25 April 2013 in Nunspeet. (Photo: EDGaR/J.-F. Auger) Two researchers discuss a poster on gas research during the Fifth Research Day on 25 April 2013 in Nunspeet. (Photo: EDGaR/J.-F. Auger)

After three years of research, the program starts to deliver results on the role of gas in the transition towards sustainable energy. The Fifth Research Day, held in Nunspeet on 25 April, was the occasion to present them. Since the program is carried from a multidisciplinary perspective, these results are about a broad range of topics, from new gas quality up to the future of gas via new methods of measurement. 

New gas quality

Most of the upcoming changes and consequences will be related to the advent of new gas quality, for example biogas, synthetic gas and hydrogen. These new gases will be added to or replace natural gas in use in the Netherlands. Luc Rabou, from ECN, and his team work on new advanced green gas technologies.

In a first project, they search for methods to make green gases out of dry and wet biomass. Among many realizations, they have designed and constructed a pressurized hydrodesulphurization reactor to test the conversion of organic sulfur. They have also set up a supercritical water gasification device.

In a second project, Mr Rabou and his team search for ways to convert biomass into gas at acceptable quality and at reasonable costs. They have constructed a test rig of substitute natural gas, and they have tested adsorbents for sulfur removal. Finally, since these new technology have economic implications, they are analyzing the cost-price relation versus gas quality for methods of green gas production.

“Substitute natural gas (SNG) can be produced from biomass,” reported Bram van der Drift, from ECN, and his colleagues. “Large amounts of gas require large amount of biomass and large-scale plants.” A scaled up substitute natural gas production plant can achieve economy of scale, they found out. It provides further energy efficiency by increasing the gasification pressure and allows the co-production of green chemicals.

Synthetic methane promises to become a “vector for energy storage and transport,” claimed Stephane Walspurger, from ECN, and his team. Electricity made out of renewable energy can be converted into methane, which, in turn, can be stored as a flexible source of energy — with a highly efficient conversion chain. Mr Walspurger and his team put their efforts into the solid oxide electrolyser cell, by carrying both mathematical modeling and laboratory experiments. 

Impact of new gas on materials

New gases may have several effects on materials in the transmission infrastructure. René Hermkens, from Kiwa Technology, reported on a series of long-term tests on materials and joints used in the current gas network. He included both narrow and wide band gases.

Mr Hermkens explained that components, made of metal or polymer, are exposed to new gases in laboratory and in the field. These materials are tested before and after gas exposures to determine the effect of gases components on their initial properties. Mr Hermkens wants to obtain the concentration limits of trace components that can be allowed into the grid without deteriorating the assets.

“The emergence of new and sustainable gases with possible higher hydrocarbons and the trend towards transporting gas at higher pressures may lead to condensation,” wrote Sander Huitema and Maarten Duyff from DNV KEMA. They have therefore investigated the possibility of condensation with a mathematical model that has been tested at variable temperature and gas flows.

New gas quality raises the issue of their detectability in case of gas leakage, which matters with respect to the security of operation. Michiel van der Laan, from Kiwa Technology, and his colleagues have built an experimental set up to produce gas leakages at various density, position and size of leakage. He found out that “effect of density on maximum concentration is significant,” and that “effect on detectability and time to detection is not critically affected.” 

Up to the end-users

New gas will have an impact while combusted in end-user equipments such as motor engines. “Small variations in the gas composition can affect the autoignition behavior of the unburned end-gas in the cylinder,” wrote Martijn van Essen, from DNV KEMA, and his colleagues.

As a consequence, there are “possible occurrence of unwanted autoignition of the end gas in spark-ignited engines, known as knock.” To solve the problem, they have tested a thermodynamic model for different types of engines and types of gas composition.

Domestic gas boilers will be affected as well by new gas quality. “Behavior of end-used equipment with ‘new’ gases can be different from that with traditional distributed (natural) gases,” wrote Sander Gersen, from DNV KEMA, and his colleagues.

As part of their researches, they have developed and demonstrated “a novel type of gas appliance that can accept any type of gas.” This new boiler monitor and adjust gas the combustion to the incoming change of gas composition. It offers several advantages over available commercial boilers. 

New methods

Researchers have conceived new measurement methods, still in relation to the impact of new gas qualities on the performance and safety of end-user equipments. The combustion of siloxanes, a component found in biogas, can be dangerous when particles deposit on heat exchangers. “Specification for siloxanes must guarantee no deterioration in performance of gas utilization equipment during lifetime of domestic equipment,” explained Martijn van Essen, from DNV KEMA, and his colleagues.

To determine these specifications, they have carried laboratory experimentations with a particular concern for the effects of silica deposition on the performance of the equipment. “Size of cluster, aggregates, agglomerates depends upon residence time, temperature and silicon in fraction in fuel,” reads one of their conclusion. The results will have practical applications in the determination of standards for the injection of biogas in the transmission grid of natural gas.

Another method has been developed for the measurement of soot, carbon particles that result from incomplete combustion of gas. “Soot formation due to new gases in end-user equipment may cause soot deposition resulting in clogging and safety issues, while in equipment dependent on soot, soot formation may diminish,” wrote Pieter Visser, from DNV GL, and his collaborators.

“A statistical model is developed based on the equivalence ratio at which soot formation starts and the slope of the soot concentration as function of equivalence ratio graph,” they wrote. The model can be used in practice for the prediction of soot formation. It has been validated experimentally in laboratory with the method of laser induced incandescence. 

Storage technologies

Gas storage technologies are under investigation, as they can provide solutions to the balancing between production and demand for energy. With respect to the production of new gas quality, they can be applied to solve the problem of an increasing decentralized production of gas. Desti Alkano, from the University of Groningen, and her colleagues aim to “develop gas storage management based on prices, helping prosumers to regulate costs.”

They think that the introduction of price signals can contribute to the coordination of the technical system. They assume that prosumers search to “minimizing the cost of inventory while minimizing gas storage level and the imbalance network,” Ms Alkano wrote. Computer simulation on typical gas demand pattern shows that this price mechanisms tend to reduce the balance towards zero.

Storage technologies found their role in balancing the production of energy between the gas and electricity networks. Since gas can be stored and converted into electricity, the challenge lies in finding the optimal configuration between both in relation to the patters of electricity demand.

Marietta de Rooij, from the Hanze University of Applied Sciences, and her colleagues, as part of a project on decentralized gas storage are using the Delphi and Mathlab methods. They have particularly investigated advanced technologies for gas storage such as methane sorption and methane hydrates. They consider not only the technical aspects of these technologies, but also the social and legal license to operate them.

Economic, social and legal aspects

Distribution system operators can rely on real option analysis. This technique valuates strategic investments for example in the gas infrastructure, as showed by a poster by Cees Pulles from Kiwa Technology. After having analyzed patterns of supply and demand and made an inventory of the infrastructure, an operator can optimize its investments by using a classical Monte Carlo method to generate possible outcomes of his investments.

With the diversification and decentralization of renewable energy sources, distribution system operators took part in energy communities. Users and small producers have constituted them around the energy system. Timothy Cayford, from Delft University of Technology, reported the result of a pilot case study on one of these communities. 

He said that he will carry further cases study, notably on the island of Texel and Schiermonnikoog and in Groningen. Thereafter, he will analyze the results to determine the degree of alignment between the technology and institutions which lies at the core of the governance system of these small energy communities.

Laws and regulations need to be adjusted to the new technological development related to new gases. “How the introduction of new energy sources may require changes in the legal framework?” asked Pablo Ferrara from the University of Groningen. One side of the question is addressed by studying technical risks that the injection of biomethane poses and the liability of companies that do it.

Another side of the question relates to the impact of law on the development of energy networks. One of the key juridical notions is the non-discrimination in relation to grid access. “Non-discriminatory network operation is not an aim in itself; it serves as a prerequisite to ensure equal market entry and competition in energy markets,” Mr Ferrara stated. 

The future of gas

Determining what will be the future energy demand mix remains difficult. Markets and technology, while developing, create uncertainties. Sibel Eker, from Delft University of Technology, is using system dynamics methodology to simulate the impact of factors such as biomass supply, pipelines imports, unconventional gas exploitation, etc., on the energy system over time. She performed runs with demand coverage, import dependency and renewable gas ratio scenarios.

Stakeholders of the energy industry have their own vision of the future. With the Q methodology, a method that transforms subjective views into quantitative data, Olga di Ruggero and Eefje Cuppen from Delft University of Technology have analyzed the content of interviews made with these stakeholders. A group of stakeholders thinks that the market will decide, while another one thinks that climate change will be the driver.

Another group, who believes in an all-electric society, thinks that renewables will be introduced and, as a consequence, gas will play a minor or no role. Opposite to this group, stakeholders perceive that gas will be part of the future, for it is a flexible source of energy. Even further on this view, a fourth group of stakeholders thinks that gas is simply part of the solution. True or false, these discursive representations of the future are often referred in decision making.

Specialists have produced rational representations of the future by publishing scenarios based on empirical data. Gideon Laugs, from the University of Groningen, and Bert Kiewiet, from DNV KEMA, are making a systematic review of the literature to understand the role of renewable and gas in the long-term energy transition. They pay attention to political, economic, social, technical and environmental drivers of the energy transition.

All in all, these research results are representative of the projects carried in the framework of the Energy Delta Gas Research, which aims at ensuring gas a role in the transition towards sustainable energy. 

By Jean-François Auger