14 Externe wissenschaftliche Einrichtungen
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Item Open Access Enhancement of the REMix energy system model : global renewable energy potentials, optimized power plant siting and scenario validation(2014) Stetter, Daniel; Müller-Steinhagen, Hans (Prof. Dr.-Ing. habil. DEng/Auckland)As electricity generation based on volatile renewable resources is subject to fluctuations, data with high temporal and spatial resolution on their availability is indispensable for integrating large shares of renewable capacities into energy infrastructures. The scope of the present doctoral thesis is to enhance the existing energy modelling environment REMix in terms of (i.) extending the geographic coverage of the potential assessment tool REMix-EnDaT from a European to a global scale, (ii.) adding a new plant siting optimization module REMix-PlaSMo, capable of assessing siting effects of renewable power plants on the portfolio output and (iii.) adding a new alternating current power transmission model between 30 European countries and CSP electricity imports from power plants located in North Africa and the Middle East via high voltage direct current links into the module REMix-OptiMo. With respect to the global potential assessment tool, a thorough investigation is carried out creating an hourly global inventory of the theoretical potentials of the major renewable resources solar irradiance, wind speed and river discharge at a spatial resolution of 0.45°x0.45°. A detailed global land use analysis determines eligible sites for the installation of renewable power plants. Detailed power plant models for PV, CSP, wind and hydro power allow for the assessment of power output, cost per kWh and respective full load hours taking into account the theoretical potentials, technological as well as economic data. The so-obtined tool REMix-EnDaT can be used as follows: First, as an assessment tool for arbitrary geographic locations, countries or world regions, deriving either site-specific or aggregated installable capacities, cost as well as full load hour potentials. Second, as a tool providing input data such as installable capacities and hourly renewable electricity generation for further assessments using the modules REMix-PlasMo and OptiMo. The plant siting tool REMix-PlaSMo yields results as to where the volatile power technologies photovoltaics and wind are to be located within a country in order to gain distinct effects on their aggregated power output. Three different modes are implemented: (a.) Optimized plant siting in order to obtain the cheapest generation cost, (b.) a minimization of the photovoltaic and wind portfolio output variance and (c.) a minimization of the residual load variance. The third fundamental addition to the REMix model is the amendment of the module REMix-OptiMo with a new power transmission model based on the DC load flow approximation. Moreover, electricity imports originating from concentrating solar power plants located in North Africa and the Middle East are now feasible. All of the new capabilities and extensions of REMix are employed in three case studies: In case study 1, using the module REMix-EnDaT, a global potential assessment is carried out for 10 OECD world regions, deriving installable capacities, cost and full load hours for PV, CSP, wind and hydro power. According to the latter, photovoltaics will represent the cheapest technology in 2050, an average of 1634 full load hours could lead to an electricity generation potential of some 5500 PWh. Although CSP also taps solar irradiance, restrictions in terms of suitable sites for erecting power plants are more severe. For that reason, the maximum potential amounts to some 1500 PWh. However, thermal energy storage can be used, which, according to this assessment, could lead to 5400 hours of full load operation. Onshore wind power could tap a potential of 717 PWh by 2050 with an average of 2200 full load hours while offshore, wind power plants could achieve a total power generation of 224 PWh with an average of 3000 full load hours. The electricity generation potential of hydro power exceeds 3 PWh, 4600 full load hours of operation are reached on average. In case study 2, using the module REMix-PlaSMo, an assessment for Morocco is carried out as to determine limits of volatile power generation in portfolios approaching full supply based on renewable power. The volatile generation technologies are strategically sited at specific locations to take advantage of available resources conditions. It could be shown that the cost optimal share of volatile power generation without considering storage or transmission grid extensions is one third. Moreover, the average power generation cost using a portfolio consisting of PV, CSP, wind and hydro power can be stabilized at about 10 €ct/kWh by the year 2050. In case study 3, using the module REMix-OptiMo, a validation of a TRANS-CSP scenario based upon high shares of renewable power generation is carried out. The optimization is conducted on an hourly basis using a least cost approach, thereby investigating if and how demand is met during each hour of the investigated year. It could be shown, that the assumed load can safely be met in all countries for each hour using the scenario's power plant portfolio. Furthermore, it was proven that dispatchable renewable power generation, in particular CSP imports to Europe, have a system stabilizing effect. Using the suggested concept, the utilization of the transfer capacities between countries would decrease until 2050.Item Open Access Balancing of intermittent renewable power generation by demand response and thermal energy storage(2015) Gils, Hans Christian; Thess, André (Prof. Dr. rer. nat.)Balancing of intermittent renewable power generation from wind and solar energy is one of the central challenges within the energy system transformation towards a more sustainable supply. This work addresses the potential role of flexible electric loads and power-controlled operation of combined heat and power (CHP) plants in meeting increasing balancing needs in Germany. It conducts an enhancement of the cross-sectoral REMix model, which is designed for the preparation and assessment of energy supply scenarios based on a system representation in high spatial and temporal resolution. The analysis is composed of three fundamental parts. The first part is dedicated to the quantification of theoretical potentials for demand response (DR), district heating (DH) and industrial CHP in Europe. Special attention is given to the geographic distribution of potentials, as well as the derivation of hourly heat and electricity demand profiles. In the second part, the linear optimization model within REMix is extended by DR and the heating sector, enabling economic assessments of the balancing function of flexible electric loads and power-controlled heat supply. In the third part, REMix is applied to assess the future energy supply in Germany, making use of the model enhancements and identified potentials. In order to account for different renewable energy (RE) and grid capacity development paths, as well as transport and heat sector structures, nine scenarios are considered. For each scenario, least-cost dimensioning and operation of DR capacities, as well as heat supply systems are evaluated. According to the REMix results, the application of DR is mostly limited to short time peak shaving of the residual load. This implies that its focus is on the provision of power, not energy. As a consequence of different cost structures, the exploitation of available DR potentials is attributed almost exclusively to industrial and commercial sector loads, whereas those in the residential sector are hardly accessed. The model results indicate that the temporal availability of DR potentials, as well as their characteristic intervention and shift times are particularly suited for a combination with PV power generation. In the simulations, power-controlled heat supply has proven to be an effective measure to increase RE integration. It is achieved by a modified operation pattern of CHP and - to a lower extent - heat pumps (HP) enabled by thermal energy storage (TES) on the one hand, and an utilization of surplus power for heating purposes on the other. Due to the greater potential and thus longer storage times of TES, as well as the comparatively low investment costs of electric boilers, an enhanced coupling between power and heat sector is found to be especially favorable in combination with wind power utilization. Load shifting across all sectors provides substantial amounts of positive balancing power, which can substitute other firm generation capacity. The highest load reduction is achieved by controlled electric vehicle charging, lower contributions come from adjusted HP operation and other DR. As a consequence of higher RE integration, load shifting and power-controlled heat supply can contribute substantially to CO2 emission reductions in Germany. However, this is only the case if the additional balancing potentials are not applied as well for an economically motivated shift in power generation from low-emitting to high-emitting fuels. Furthermore, load flexibility and enhanced power-heat-coupling can enable energy supply cost reductions, arising from the substitution of back-up power plant capacity on the one hand, and a more cost-efficient power and heat supply on the other. The model application reveals that electric load shifting and power-controlled CHP operation are not competing but complementary measures in the realization of higher RE integration and lower back-up capacity demand. Negative interferences between both balancing options are found to be very small. On the contrary, they even promote each other, for example in the reduction of RE curtailments. Based on the REMix results it can be concluded that both DR and power-controlled heat supply enabled by TES are important elements in a future German energy system mainly relying on renewable sources.