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A new software for the design of biomethane networks

2014-04-23

A new software can change the way distribution system operators design biomethane networks and their integration with the gas distribution grid

Taede Weidenaar, in “Designing the biomethane supply chain through automated synthesis,” proposes a tool for the design of the biomethane supply chain and the gas distribution grid. Taede Weidenaar, in “Designing the biomethane supply chain through automated synthesis,” proposes a tool for the design of the biomethane supply chain and the gas distribution grid.

With the increasing production of biomethane, distribution system operators (DSO) will have to make design choices for the gas distribution grid. Is it worth using the biomass potential? If yes, then where to locate the biomass digester? And what about the location of the upgrading plant? And, finally, what are the balancing options? Taede Weidenaar, from the University of Twente, has created a tool that supports decision making on these questions. 

The current approach to the design of the biogas grid suffers from several drawbacks. “There is a producer of biomass, let’s say a farmer, who wants to produce biomethane,” Weidenaar said in an interview.  “He goes to a consultancy agency. They find out what is the best option for him. And they design the whole supply chain.”

The DSO’s role is limited to deciding on the injection of biomethane into the gas distribution grid. Weidenaar argues that this might lead to the implementation of a design that is not optimal. “If you look at societal costs, often the current approach creates higher costs for society, because the owner of the biomass does not have to pay for investments in the gas grid,” he said.

“If the DSO could be involved in an earlier stage in the design process and if someone could consider the societal issues, then the result could be more beneficial for the society," he said. Weidenaar has realized no satisfying method can give specific advices on necessary investments, depending on the current configuration of the gas distribution grid and the location of biomass. 

An innovative tool

Weidenaar has chosen an innovative approach. “My method looks for several possible solutions,” he said. “The reason behind it is that, in my opinion, you cannot catch a design in one single value.” Indeed, using the tool developed by Weidenaar, the DSOs can consider the profit margins, the quantity of carbon dioxide emissions mitigated, the efficiency in the use of energy, etc.

Moreover, Weidenaar’s tool allows flexibility in the interpretation of the proposed solutions and inclusion of qualitative information later on in the final choice. Users of the tools are empowered to know the pros and the cons of the given solutions, instead of having one single anything-fits-all design solution.

Weidenaar has developed a computer program that allows users to upload quantitative data of certain geographical regions. The data includes the location of the current gas pipelines, district stations and gas consumers, as well as locations with biomass. For this geographical region, it generates “candidate solutions for the design of the biomethane supply chain and additionally it determines  the performance of each design,” according to his thesis. A solution describes among other the location and size of digesters and upgrading plants, and into which gas grid the biomethane will be injected.

Weidenaar has conceived his method so that several groups can participate in the design of the gas grid from the producer of biomass up to the local government via the gas distribution system operators and the citizens. 

Design of the chosen solution in the tight market scenario for a rural region (illustration: T. Weidenaar) Design of the chosen solution in the tight market scenario for a rural region (illustration: T. Weidenaar)

Urban, rural and middle regions

“There are many ways to configure the biomethane infrastructure,” Weidenaar said. In one configuration, the biomass owners operates and owns the whole process, by owning the biomass, the digester and the upgrading station. In another configuration, the biomass producers owns and operates a digester and share the upgrading plant with other biomass producers.

And in the last configuration, they share the ownership of both the digester and of the upgrading plant. “The more they cooperate, the higher the profitability,” Weidenaar’s argued. It’s an effect of the economy of scale.

Weidenaar has modelled the network configuration for urbanized, rural and middle regions. “The most important distinguishers between the regions is the biomass availability and the other one is biogas demand,” he said.

Urban regions do have a high gas demand with little biomethane production capacity. “A single grid is enough to consume all the biomethane,” he said. Rural regions have in general more biomass production capacity, but they have a lower gas demand. It results that “you have to use the demand of each non-connected individual grids.”

All in all, the decision support tool that Weidenaar developed has several advantages over existing ones. It encapsulates the whole biogas supply chain, “from biomass supply to injection in the gas grid and dealing with a temporary surplus of biomethane,” according to the conclusion of his thesis.

It embeds several relevant performance indicators such as “the CO2 emission reduction, net energy production, and economic performance.” The model is “specially explicit,” by taking into account the location of the physical components of the supply chain and the spatial configuration of the gas distribution grid.

Weidenaar’s thesis “Designing the biomethane supply chain through automated synthesis,” has been executed in the framework of the research project Towards sustainable gas distribution systems. DSOs will be interested in the manifold applications of Weidenaar's new software. 

By Jean-François Auger