Poul Alberg Østergaard

Transmission-grid requirements with scattered and fluctuating renewable electricity-sources

Electricity generation in Denmark is undergoing a gradual transition from taking place in a few large power-plants to taking place at many small and geographically scattered CHP (combined heat and power) and wind-power plants. A new situation is thus being created for the transmission grid. From a mainly unidirectional flow from the few large power plants to the scattered consumption points, the flow is changing to a bidirectional flow subject to scattered electricity production. In this article, the requirements of the transmission grid are analysed in (a) a year 2020 situation with power balancing (matching production and consumption) as it is now on the few large power plants, and (b) a year 2020 situation with geographically-scattered power balancing using e.g. CHP plants, heat pumps, and heat storage. Geographic modelling of production and consumption loads combined with grid analyses reveal that the transmission grid needs reinforcements to meet transmission demands unless geographically scattered power balancing is introduced. The analyses also emphasize the importance of reactive compensation especially of wind turbines.

Sustainable Towns: The Case of Frederikshavn – 100% Renewable Energy

A number of Danish energy experts in 2006 made the proposal that Denmark should convert a town to 100% renewable energy by 2015. The experts suggested Frederikshavn in the northern part of Denmark for a number of reasons: The town area of 25,000 inhabitants is well defined, the local support is high, and Frederikshavn already has several big wind turbines at the harbour. In February 2007 the city council unanimously decided to go for the project and set up a project organisation involving utilities and municipality administrators. Moreover, local industry and Aalborg University are involved in the project.

Heat savings in energy systems with substantial distributed generation

In Denmark, the integration of wind power is affected by a large amount of cogeneration of heat and power. With ancillary services supplied by large-scale condensation and combined heat and power (CHP) plants, a certain degree of large-scale generation is required regardless of momentary wind input. A lowered district heating demand and thereby lowered CHP-bound electricity generation would appear to increase the possibility of integration wind power but due to the ancillary services supplied by CHP plants, the situation is in fact the opposite. Heat savings may not be technically feasible, if a certain production is required regardless of whether over-all electricity generation is sufficient. This article analyses this and although heat savings do have a negative impact on the amount of wind power the system may integrate a given moment in certain cases, associated fuel savings are notable and by far supersede the ‘loss’ in wind power integration.

Climate Change Mitigation from a Bottom-up Community Approach

Publisher Summary Throughout the world, increasing attention is being paid to climate change mitigation. But while ambitious national targets are hard to come by, several regions, cities, towns, institutions, and individuals have taken matters into their own hands. Rather than awaiting international agreement or national targets, these established their own ambitious targets for reducing carbon dioxide emissions and are in the process of findings ways and means to meet these targets. The ambitious targets on a sub national level which cannot replace ambitious national and international targets are reviewed here. In as much as the reductions would be limited and there would be a plenty of free riders. Various levels serve as impetuous for more ambitious targets by demonstrating a will to policy makers as well as finding and demonstrating feasible options. It helps confront the previous paradigm that fossil-fueled economies are the only viable options and renewable energy systems cannot supply the required energy services at a competitive cost.

A comparison of diesel, biodiesel and solar PV-based water pumping systems in the context of rural Nepal

Nepal is heavily dependent on the traditional energy sources and imported fossil fuel, which has an adverse impact on the environment and economy. Renewable energy technologies promoted in the country are regarded as a means of satisfying rural energy needs of the country for operating different rural end-uses. In this context, this article is prepared to investigate energy alternatives to pump drinking water in one of the remote rural village of Nepal, which has no means of running water source. Analyses in this article are based on the formulation of three technical scenarios of water pumping using petro-diesel, jatropha-based biodiesel and solar photovoltaic pumps. The technical system design consists of system sizing of prime mover (engine, solar panel and pumps) and estimation of reservoir capacity, which are based on the annual aggregate water demand modelling. With these investigations, detailed financial modelling is carried out in a spreadsheet to compare the alternatives on the basis of the economic parameters; net present value, equivalent annualised cost and levelised cost of water pumping. Analysis is carried out considering different influential parameters; water head, discharge, incentives on the investments, which have effects on the cost of pumped water. Likewise, in case of biodiesel-based system, different yield rate of jatropha plants is also considered in estimating the cost of producing biodiesel. It is found that for operating a biodiesel-based pumping system for the study area, the levelised cost of pumping 1 L of water is higher than that of a solar pump and even higher when compared with diesel, if the seed yield per plant is less than 2 kg and without subsidy on the investment cost of cultivation and processing. With the productivity of 2.5 kg/plant, a biodiesel-based system is more attractive than that of the diesel-based pump, but still remains more expensive than that of solar pump. From the technical perspective (reliability and easiness in operation) and economic evaluation of the technical alternatives, solar pumping system is found to be the most viable solution to pump drinking water in the project area.

Chapter 6 – Analysis: Smart Energy Systems and Infrastructures

This chapter introduces the concept of smart energy systems. As opposed to the smart grid concept, which takes focuses solely on the electricity sector, smart energy systems includes the entire energy system in its approach to identifying suitable energy infrastructure designs and operating strategies. The typical smart grid focus on the electricity sector often leads to the definition of transmission lines, flexible electricity demands, and electricity storage as the primary means to deal with the integration of fluctuating renewable sources. However, due to the intermittent nature of wind power and similar sources, these measures are not very effective or cost-efficient. The most effective and least-cost solutions are found when the electricity sector is combined with the heating sector and/or the transportation sector. Moreover, the combination of electricity and gas infrastructures may play an important role in the design of future renewable energy systems.

Analysis: Smart Energy Systems and Infrastructures

This chapter introduces the concept of smart energy systems. As opposed to the smart grid concept, which takes focuses solely on the electricity sector, smart energy systems includes the entire energy system in its approach to identifying suitable energy infrastructure designs and operating strategies. The typical smart grid focus on the electricity sector often leads to the definition of transmission lines, flexible electricity demands, and electricity storage as the primary means to deal with the integration of fluctuating renewable sources. However, due to the intermittent nature of wind power and similar sources, these measures are not very effective or cost-efficient. The most effective and least-cost solutions are found when the electricity sector is combined with the heating sector and/or the transportation sector. Moreover, the combination of electricity and gas infrastructures may play an important role in the design of future renewable energy systems.

Sustainable Towns: The Case of Frederikshavn Aiming at 100% Renewable Energy

Abstract In 2006, a number of Danish energy experts proposed that Denmark should convert the supply of a specific town to 100% renewable energy by 2015. The experts suggested Frederikshavn in the northern part of Denmark for the following reasons. The town area of 25,000 inhabitants is well defined, the local support is high, and Frederikshavn already has a number of large wind turbines at the harbor. In February 2007, the city council unanimously decided to go for the project and set up a project organization involving utilities and municipality administrators. The local industry and the Aalborg University are also involved in the project. This chapter presents the methodology of mapping the existing energy system, including transport, and defining the share of renewable energy, which is approximately 20% at present. It introduces a proposal for a potential 100% renewable energy system for the year 2015 and a number of realistic short-term first steps, which will raise the share of renewable energy in Frederikshavn to approximately 40% by 2009 or 2010. This chapter describes detailed hour-by-hour energy system analyses of the proposal for a 100% renewable energy system. Also, it relates the proposal to the perspective of converting Denmark to a 100% renewable energy supply system.

Analysis of Large-scale Integration of Renewable Energy Sources in the Mexican Electricity System

The Mexican electricity consumption is highly based on fossil fuels. In 2012 only 15% of the electricity generation was produced using renewable energy sources (RES) and most of the new installed capacity during the last decade has been based on combined cycle power plants. On the other hand, Mexico is a land of ample opportunities for renewable energy exploitation that could lower its dependency on fossil fuels. Recently, the Mexican Congress approved a regulation limiting fossil fuel-based electricity generation to 65% by the year 2024, to 60% by 2035 and to 50% by 2050. In this work the authors investigate the potential for renewable energy integration into the Mexican electricity system. The authors construct three scenarios (low, mid and high biomass) for achieving the 2024 target and analyse the electricity system response to varying contributions of wind and solar power production to the scenarios. The minimum complementary capacity based on fossil fuels needed to cover the demand without electricity imports is also assessed. Results indicate that within each scenario several combinations of bio, wind and solar power make a minimum of 35% RES electricity production possible. However, in every scenario there is only one combination resulting in the minimum overall capacity. Biomass has the highest effectiveness in terms of high RES production with the lowest needed overall power generating capacity.

Renewable Energy Systems

This chapter introduces the concept of smart energy systems. As opposed to the smart grid concept, which takes focuses solely on the electricity sector, smart energy systems includes the entire energy system in its approach to identifying suitable energy infrastructure designs and operating strategies. The typical smart grid focus on the electricity sector often leads to the definition of transmission lines, flexible electricity demands, and electricity storage as the primary means to deal with the integration of fluctuating renewable sources. However, due to the intermittent nature of wind power and similar sources, these measures are not very effective or cost-efficient. The most effective and least-cost solutions are found when the electricity sector is combined with the heating sector and/or the transportation sector. Moreover, the combination of electricity and gas infrastructures may play an important role in the design of future renewable energy systems.