/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

Presently for pressures up to about 10 bar, plastic pipeline materials (like PE ) are the preferred option. Up to now a suitable plastic pipeline system for pressures up to about 16 bar is not available. In this paper a tailor-made fibre-reinforced thermoplastic pipeline (RTP) system (pipes and joints ) is described, which is a cost-effective option for use in gas distribution systems up to about 20 bar. Development and qualification of such a system was a joint effort of various European gas companies, universities and test institutes, and a pipeline and fitting manufacturer. To date RTP has been used primarily in oil, gas and water applications at high pressures, where the material has proven to be more cost-effective than steel. The suitability of the RTP system has been assessed by performing many mechanical and physical tests on the system components and joints. Much attention has been given to determine the long-term behaviour under internal pressure. The resistance to third party damage has also been assessed by carrying out full-scale field tests. Special attention has been given to develop a relatively simple and cheap jointing technique, based on the well-proven electrofusion jointing technique for conventional PE pipelines. In long-term tests it has been shown that the strength of these joints outperforms the strength of the pipeline materials. It is also shown that this new pipeline system fulfils the requirements of recently issued (draft) specifications for such pipeline systems for gas ( e.g. ISO and German (DVGW) specifications ). The results of the various physical and mechanical tests show that this RTP system has a performance fulfilling all the requirements of the (draft) international specifications. The long-term (50-year) strength of this system exceeds 42 bar and in all tests the joints are stronger than the pipeline material. The RTP system is also resistant to third party digging activities. The RTP system is a cost-effective option for situations where long lengths of pipes can be installed, like so-called ploughing techniques. In these situations the pipes can be installed in long lengths (200 to 300 meters ) from coils. In this case only a few joints have to be made, thereby reducing construction costs. Compared to steel systems, considerable cost reductions, in the order of 25 %, can be obtained. Presently these RTP systems are available in 4” (100 mm ) and 5” (125 mm).

Reinforced thermoplastic pipeline (RTP) systems for gas distribution

Innovatie in energienetwerken

This paper presents the results of work that was performed at the request of TEPPFA , The European Plastics Pipes and Fittings Association, on the issue of “Combined loading” (external and internal loading) of buried thermoplastics pressure pipes. The work is of great importance for users and designers of thermoplastics pipes. Quite often users are confused about the design of thermoplastics pipes, especially when the design is compared with traditional methods, originally developed for the design of buried linear-elastic pipe materials. Users of water mains for instance, demand a clear relation between the product pressure classification (PN) and the operational pressure (PFA) to be given in product standards. Tests have been performed to check if, and to what extent, tensile stresses induced by internal pressure shall be added to the tensile bending stress induced by external loading. Tests were performed on radially deflected as well as axially bent pipes. The time to failure was recorded. It was shown that the time to failure in these combined loaded pipe samples is the same as for straight non-deflected pipe subjected to the internal hydrostatic pressure only. Recommendations for the design of buried thermoplastic pipes both for pressure and nonpressure applications are given, based on the results found in this study.

Mannes Wolters

Papers

Reinforced thermoplastic pipeline (RTP) systems for gas distribution

Innovatie in energienetwerken

Combined Loading of Buried thermoplastics Pressure Pipes

The performance of a gas distribution system of ductile PVC

Long-term tests on electro fused joints in PE pipes