The issue of a solid energy provision

D'Haeseleer William D. The issue of a solid energy provision. In: Bulletin de la Classe des sciences, tome 17, n°1-6, 2006. pp. 53-54

Long-term Unit Commitment optimisation for large power systems: unit decommitment versus advanced priority listing

Unit Commitment (UC) is a term used for the strategic choice whereby the available power plants have to be on-line every time. Most UC models described in the literature are specifically designed for the power utilities. They are typical short-term models for relatively small power-systems. Apart from practical use in the utilities themselves, UC is also implemented in the broader context of electricity-generation modelling. For these purposes, however, the power systems can be much larger and the time scale more extended. Since UC is only a minor part of these models, the calculation time dedicated to UC has to be limited, thereby possibly sacrificing somewhat on accuracy. Two methods are compared. Unit Decommitment (UD), which is considered completely accurate and Advanced Priority Listing, which is less accurate but also less complicated. Simulations demonstrate that UD is slightly more accurate (0.03-0.6%), but takes much more calculation time (5-10 times more) than Advanced Priority Listing.Electricity generation modelling Unit Commitment (UC) Unit Decommitment (UD) Advanced Priority listing

Critical evaluation of methods for wind-power appraisal

In the literature, several methods are being used to evaluate the contribution of wind energy conversion systems in a broader power-generating system. However, not all of them guarantee accurate results. This paper critically reviews several methods used in the literature for such reliability evaluations. There are three types of methods characterised by the details considered and the simplifications made: (1) methods using complete chronological data; measured or calculated; (2) methods using a truncated set of chronological data and (3) methods disregarding the chronology all together. In order to test the different possible simplifications, we calculate a case study for a potential wind farm. The result of the full chronological calculation is used as a benchmark to which the results of the simplified methods can be verified. The truncated method is found to be reliable when more than the top 25% chronological values are used. The methods in which the chronology is disregarded were not found accurate because of the significant correlation between consecutive wind-speed measurements embedded in the chronological data. We therefore conclude that the most accurate results are obtained when the full chronology of both the wind-power output and the power-generation requirement are used. Most simplifications considered with the aim to limit the amount of data needed and thus to save computation time and data-gathering effort are not really justified.Wind power Fluctuating power sources Reliability

Impact of wind power on natural gas markets : inter market flexibility

Date of conference: 23-25 June 2010The introduction of massive amounts of intermittent wind power raises challenges for the proper balancing of the power system. For a number of reasons combined cycle gas turbines are the back-up technology of consequence. Therefore, the flexibility needs of the power generation market are actually transferred to the gas market. A first step is proposed towards a model to quantitatively study this inter market flexibility. Results of our stylised model show that wind power intermittency causes CCGT production to become very variable. Line-pack flexibility appears to be the best suited instrument to respond to this variability both in size and in frequency. More accurate power and gas systems need to be modelled to obtain practically useful results, though

SHORT-TERM CO2 ABATEMENT IN THE EUROPEAN POWER SECTOR: 2005–2006

This paper provides an estimate of short-term abatement of CO2 emissions through fuel switching in the European power sector in response to the CO2 price imposed by the EU Emissions Trading Scheme (EU ETS) in 2005 and 2006. The estimate is based on the use of a highly detailed simulation model of the European power sector in which abatement is the difference between simulations of actual conditions with and without the observed CO2 price. We estimate that the cumulative abatement over this period was about 53 million metric tons. The paper also explains the complex relationship between abatement and daily, weekly, and seasonal variations in load, relative fuel prices, and the price of CO2 allowances.CO2 abatement, electricity generation simulation, European Union Emission Trading Scheme, fuel switching

Impact of large amounts of wind power on the operation of an electricity generation system: Belgian case study

Wind power can have considerable impacts on the operation of electricity generation systems. Energy from wind power replaces other forms of electricity generation, thereby lowering overall fuel costs and greenhouse gas (GHG) emissions. However, the intermittency of wind power, reflected in its variability and relative unpredictability restrains the full potential benefits of wind power. The variable nature of wind power requires power plants to be ready for bridging moments of low wind power output. The occurrence of forecast errors for wind speed necessitates sufficient reserve capacity in the system, which cannot be used for other useful purposes. These forecast errors inevitably cause efficiency losses in the operation of the system. To analyse the extent of these impacts, the Belgian electricity generation system is taken as a case and investigated on different aspects such as technical limitations for wind power integration and cost and GHG emissions' reduction potential of wind power under different circumstances.Wind power Operational cost reduction Greenhouse gas Technical barriers

Considerations on the backup of wind power: Operational backup

The introduction of wind power into an electricity-generation system on a large scale brings about challenges for the evolution and operation of this system: backup for wind power becomes a necessity. This paper defines various elements that come into play when considering backup for electricity generation from wind power. The backup is split up in capacity backup and operational backup. The focus is set on the short-term, operational aspects of the backup provision. The effects of several short-term operation related parameters are defined and analysed. Most relevant parameters for the operation and needs for wind power backup are the load profiles, the wind power output profiles and the total amount of installed wind power. These are analysed by means of a Mixed Integer Linear Programming (MILP) model through two different methods for operational backup provision, comparing the incremental cost, generated by both methods. The first method applies wind power backup through a 100% provision of additional spinning reserves. The second method does not foresee any spinning reserve and relies on the balancing by the Transmission System Operator (TSO). Both methods result in different additional charges that are being affected by the said parameters. Both the wind profile and the total amount of installed wind power are positively related to the relative cost increase. The load profile is negatively correlated to this increase. The relationship between these parameters and the development of the incremental cost provides an understanding that allows finding better equilibria in the operational backup of wind power.Wind power Backup Operational Electricity-generation system Short run MILP

Influence of massive heat-pump introduction on the electricity-generation mix and the GHG effect: Comparison between Belgium, France, Germany and The Netherlands

To evaluate the environmental impact of massive heat-pump introduction on greenhouse gas (GHG) emissions in different electricity-generation systems, dynamic simulations have been carried out for four European countries, namely, Belgium, France, Germany and the Netherlands. For this purpose, the simulations are performed with Promix, a tool that models the overall electricity-generation system. Three heating devices are considered for each country, namely classic fossil-fuel heating, heat pumps and electric resistance heating. Both direct heat-pump heating with a coefficient of performance (COP) of 2.5 and accumulation heat-pump heating with a COP of 5 are investigated. The introduction of electric heating in an electricity-generation system increases the demand for electricity and generates a shift of emissions from fossil-fuel heating systems to electrical plants. The results of the simulations reveal that the massive introduction of either heat pump or resistance heating is always favourable to the environment in France. The most environmentally friendly scenario in 2010 is projected to reduce GHG emissions by about 3.8 Mton compared to the reference scenario. In Belgium and Germany, the largest reduction in GHG emissions occurs with accumulation heat pumps. Belgium can save up to 220 kton of GHG emissions, while Germany can attain reductions of 800 kton in 2010. In the Netherlands, a significant reduction can be achieved by considering the addition of gas-fired combined cycle (CC) power plants, together with the introduction of electric heating, resulting in emissions savings of 410 kton.Heat pump Greenhouse gas (GHG) Electricity-generation system Belgium France Germany The Netherlands Dynamic simulation Promix

Edge Stability and Transport Control with Resonant Magnetic Perturbations in Collisionless Tokamak Plasmas

A critical issue for fusion plasma research is the erosion of the first wall of the experimental device due to impulsive heating from repetitive edge magneto-hydrodynamic (MHD) instabilities known as 'edge-localized modes' (ELMs). Here, we show that the addition of small resonant magnetic field perturbations completely eliminates ELMs while maintaining a steady-state high-confinement (H-mode) plasma. These perturbations induce a chaotic behavior in the magnetic field lines, which reduces the edge pressure gradient below the ELM instability threshold. The pressure gradient reduction results from a reduction in particle content of the plasma, rather than an increase in the electron thermal transport. This is inconsistent with the predictions of stochastic electron heat transport theory. These results provide a first experimental test of stochastic transport theory in a highly rotating, hot, collisionless plasma and demonstrate a promising solution to the critical issue of controlling edge instabilities in fusion plasma devices