/pdf/wind-power-modelling-and-impact-on-power-system-dynamics-4enh7yd6ir.pdf

Wind Power: Modelling and Impact on Power System Dynamics

The use of the natural-gas pipeline infrastructure for hydrogen transport in a changing market structure

Two aspects of investment in generation capacity in liberalized electricity markets are investigated: the question of whether investment will be sufficient to meet society's goals for the reliability of electricity supply (generation adequacy) and the question of how to coordinate investment in electricity generation capacity in a competitive market while bound by the physical requirements and limitations of the electricity networks. The study focuses on the situation in European electricity markets. A number of factors discourage generating companies from investing in a level of generation capacity that is optimal for society as a whole. Due to the limited possibilities for the storage of electricity and the low price-elasticity of demand, electricity prices are highly volatile. This, in addition to the lack of historical trend data (due to the short history of liberalized electricity markets), insufficient transparency and high capital costs, causes investment risk to be high. Investment risk is increased by several sources of regulatory uncertainty. Given these circumstances, it is rational for investors to be cautious. A number of policy options for improving investment incentives and for stabilizing the volume of generation capacity, called capacity mechanisms, are described and analyzed. A policy framework is introduced for evaluating them and deciding on the best policy options for different circumstances. With respect to the issue of coordinating investment in electricity generation capacity with the networks, the consequences of the choice for fixed transmission tariffs in most European countries were investigated. While fixed transmission tariffs are intended to make the market simple and transparent, paradoxically they create the need for several additional measures to compensate for their external effects. Among these, the implementation of a congestion management method ranks among the most necessary measures. The options for congestion management, given the choice for fixed transmission tariffs, are analyzed and compared.

/pdf/securing-the-public-interest-in-electricity-generation-4tk21kvsco.pdf

Securing the public interest in electricity generation markets. The myths of the invisible hand and the copper plate

Progress in Nuclear Magnetic Resonance Spectroscopy

The future of the UK gas network

It has been about fifty years ago since the first unplasticized poly(vinyl chloride) (uPVC) pipes were installed for use in gas distribution purposes. Currently, about 22,500 km of uPVC is still in use in the Dutch gas distribution network. The pipes were originally designed for a lifetime of 50 years, but due to positive experiences the question arises if (and how long) the lifetime can be extended without any concessions to safety. This is supported by the data of leak surveys presented in this paper. The amount of leaks per installed km of uPVC is even slightly lower than that of polyethylene or steel pipes. Only impact modified PVC has a better performance. The impact behaviour is presumed to be the limiting factor for the lifetime of uPVC. Therefore, the impact behaviour was studied as a function of the age. Two types of research have been carried out: instrumented falling weight tests were carried out on recently produced uPVC pipes (some of which were aged artificially) and tensile impact tests were carried out on excavated uPVC pipes which had been in service for 20 to 50 years. The overall conclusion that can be drawn from these experiments is that the most significant change in impact behaviour is likely to occur in the early stages, just after the production of the uPVC pipe. Physical ageing occurs on a logarithmic timescale, thus the changes occurring between the 20th and the 50th year of service are relatively small compared to the changes that occur in the first 20 years. This leads to the conclusion that uPVC pipes that currently show good impact behaviour, are expected to have good impact properties for many years to come.

/pdf/excellent-impact-performance-of-pvc-pipeline-materials-in-5g19yb1k9o.pdf

Excellent impact performance of PVC pipeline materials in gas distribution networks after many years of service

Integrität von PE-Gas- und Wasserleitungen der ersten Generation. Ergebnisse eines DVGW-Forschungsvorhabens. –State and residual service life of gas and water pipelines of the first PE generation. Results of a DVGW research project. –

The Dutch gas distribution infrastructure faces several significant changes in the near future. One of the major changes is the production and injection of biomethane into the gas distribution grid. The distribution system operators (DSOs) have to make investments in the gas distribution grid in order to facilitate the injection of biomethane. Numerous design choices have to be made for the biomethane supply chain and gas distribution grid. These choices, which are made in the design process, largely depend on the local situation and the DSOs' preferences. In order to support this decision making process, this paper presents a Design Support Tool (DST) that aids actively the generation of design solutions for the biomethane supply chain and gas distribution grids for user-defined regions. The focus of the paper is set on the functionality of the tool and how it can be used to improve the design process in which multiple stakeholders are involved.

Design Support Tool for Biomethane Supply Chains and Gas Distribution Grids

The long-term quality of electro fused joints in third, second and excavated first generation PE pipes was compared. Pipes from all three generations were joined using couplers produced from PE80 and PE100 resins. Six brands of PE pipes and three brands of electro fusion couplers were used and all 18 combinations were tested. Both a short-term test (the Peel Test according to ISO 13954:1997) and a long-term test (the Slow Peel Test - SPT) were used to assess joint integrity. The latter test typically takes 500 hours at 80 or 95 °C. No failures at the joint plane occurred in either of the two tests, even for excavated first generation PE pipes. Whilst in the Peel Test failures often occur in the coupler, the Slow Peel Test exclusively produces slow brittle crack growth in the PE pipe wall. The time to failure in the Slow Peel Test on the joint is therefore governed by the resistance to slow crack growth of the pipe. These resistances vary widely between first, second and third generation pipes. The scope of the Slow Peel Test programme was further widened by using it on the new type of “VRC” PE100 materials. These “Very Resistant to Cracks” pipe materials possess a much higher resistance to slow crack growth than traditional PE100 pipe materials. Improved results of Slow Peel Testing on joints made with a “VRC” material have been obtained. Up to now, unwanted joint plane failures have never been found in Slow Peel Tests on electro fused PE pipes, including excavated first generation PE pipes. Such failures can only be produced by performing Slow Peel Tests on electro fused cross linked PE pipes. On such samples, the Slow Peel test can provide much clearer differences in electro fusion joint quality than the Peel Test at 23 °C. A comparison was also made with another long-term test on electro fused joints, according to DVS 2203-4, Appendix 1. It appears that that test can only prove a longterm Fusion Factor (load ability of the joint divided by the load ability of un-fused pipe, assessed in a long-term test) of not higher than 44 %. Therefore this test is less critical for electro fused joints in PE pipes.

Mannes Wolters

Papers

Excellent impact performance of PVC pipeline materials in gas distribution networks after many years of service

Integrität von PE-Gas- und Wasserleitungen der ersten Generation. Ergebnisse eines DVGW-Forschungsvorhabens. –State and residual service life of gas and water pipelines of the first PE generation. Results of a DVGW research project. –

Design Support Tool for Biomethane Supply Chains and Gas Distribution Grids

The slow peel test as a tool for assessing the integrity of electro fused joints

Polyamide 11,12 and 6.12 for High-Pressure Gas Pipelines