/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

The most widespread application of polymers in structural applications is their use as pipe material for e.g., gas distribution systems. Pipes have a design lifetime of typically 50 years, which rules out real-time lifetime assessment methods. Here, an engineering approach is presented, which makes it possible to predict long-term ductile failure of loaded glassy polymers based on short-term tests. The approach is based upon the hypothesis that failure is governed by accumulation of plastic deformation up to a critical strain. A pressure-modified Eyring relation is employed to calculate the accumulation of plastic strain for any simple loading geometry. It is demonstrated that the approach can produce accurate quantitative time-to-failure predictions for loaded PC specimens and uPVC pipe segments.

http://www.mate.tue.nl/mate/pdfs/11566.pdf

Lifetime Assessment of Load-Bearing Polymer Glasses : An Analytical Framework for Ductile Failure

The timescale at which ductile failure occurs in loaded glassy polymers can be successfully predicted using the engineering approach presented in a previous publication. In this paper the influence of progressive physical ageing on the plastic deformation behaviour of unplasticised poly(vinyl chloride) (uPVC) is characterised and incorporated in the existing approach. With the modification it is possible to quantitatively predict long-term failures which show a so-called endurance limit. The predictions are compared with failure data of uPVC specimens which were subjected to constant or dynamic loads. In dynamic loading conditions a second type of failure mode was observed: fatigue crack growth. A brief study on the influence of the frequency and stress ratio of the applied stress signal shows that crack growth failure is not expected to occur within experimentally reasonable timescales for constant loading conditions.

/pdf/lifetime-assessment-of-load-bearing-polymer-glasses-the-3jv8hlfazy.pdf

Lifetime Assessment of Load-Bearing Polymer Glasses: The Influence of Physical Ageing

Most failures of unplasticised poly(vinyl chloride) (uPVC) pipes used in the Dutch gas distribution network originate from third party damage. Brittle pipes should therefore be replaced to ensure safe operation of the network. In this study, the relation between physical aging and embrittlement of uPVC is investigated using instrumented falling weight impact tests. The ductile to brittle transition temperature was first measured for a water pipe grade uPVC at different stages of aging. As a hypothesis, a critical stress criterion is proposed above which failure is brittle. The evolution of the ductile to brittle transition temperature that followed from the use of this hypothesis and a model for the polymer yield stress agrees qualitatively with the experimental data. A minor increase in transition temperature was observed for the water pipe grade with aging. Applying the same hypothesis to a uPVC gas pipe grade shows a more pronounced influence of physical aging.

/pdf/influence-of-physical-aging-on-impact-embrittlement-of-upvc-3ybbgs2azj.pdf

Influence of physical aging on impact embrittlement of uPVC pipes

The Dutch gas distribution grid faces several changes in the near future. Among others, the share of green gas will grow, the interaction with the electricity distribution grid and local heat grids will increase, and the grid will transform from a mono-gas system to a multi-gas system. The gas distribution grid is likely to be expanded with novel components, e.g. blending stations, gas storage sites, and gas compressor stations. Furthermore, these changes require the currently passive gas distribution grid to become a smart gas grid that monitors and controls the gas pressure, gas flow, and gas quality. Therefore, the distribution service operators need to make investments in the gas distribution grid. When looking at for example the introduction of green gas, a decision tree on the optimal green gas supply configuration can be identified. Decisions in this respect consider, among others, the location of several process steps (perform the process step locally at a small scale or centrally at a larger scale) and the addition of components like a gas storage site or a compressor station. Due to the multitude of development options for the gas distribution grid and the fact that the best solution is largely dependent on the local situation and performance criteria (e.g. CO 2 emission minimization or cost minimization), a tool is required that can generate situation specific solutions. Each solution generated by the tool should have its own advantages and disadvantages. Generating multiple options and showing the advantage and disadvantage of them provides the distribution service operators insight in the available options and eases the decision making on investments of the gas distribution grid.

Development options for the Dutch gas distribution grid in a changing gas market

In the changing Dutch energy market, the ageing gas distribution grid needs investments. There is,
however, a large uncertainty regarding certain aspects that affect the future role of this gas distribution grid, such as the eventual share of biomethane in the gas mix, whether power-to-gas will take-off and the expected lifetime of the grid. Hence, it is currently unclear what investments need to be made for the gas distribution infrastructure in order to cope with future changes. To find out how the future may unfold for the Dutch gas distribution infrastructure in 2050, four scenarios have been developed. Two key forces – a key force is a factor that has a large impact on the gas distribution grid but great uncertainty exists regarding its outcome – were chosen, namely “perceived energy resource scarcity” and “willingness and ability to reduce greenhouse gas emissions”. Each scenario sketches the future Dutch gas infrastructure by defining, among others, the extent to which biomass will be used to produce biomethane, whether fossil fuel is allowed to be burned locally, and what types of gas will flow through the gas grid. With these scenarios at our disposal, in the next research step, we will establish the impact of the scenarios on the gas distribution grid – i.e. what the layout will be and the corresponding costs – and the accompanying biomethane infrastructure. For this, 3 typical locations were chosen: a rural region, an urban region, and an intermediate region. Through a multi-objective optimization – with maximizing net present value, maximizing biomethane production, and maximizing CO2 emission reduction as objectives – the possible layout of the gas distribution grid and the biomethane infrastructure will be determined for each region. The study’s aim is to find similarities in investments among the different layouts, to come to robust investments for the gas distribution infrastructure.

/pdf/finding-robust-investments-for-the-dutch-gas-distribution-3b3aig19tm.pdf

Mannes Wolters

Papers

Lifetime Assessment of Load-Bearing Polymer Glasses : An Analytical Framework for Ductile Failure

Lifetime Assessment of Load-Bearing Polymer Glasses: The Influence of Physical Ageing

Influence of physical aging on impact embrittlement of uPVC pipes

Development options for the Dutch gas distribution grid in a changing gas market

Finding robust investments for the Dutch gas distribution infrastructure in 2050 by a scenario study