Egill Benedikt Hreinsson

Optimal short term operation of a purely hydroelectric system

The short-term production scheduling problem for a purely hydroelectric system can be simplified so that the power production and water can be managed separately. This approximation is possible when plants have large daily reservoirs with fixed or controllable heads. The model described by the authors optimizes the hourly power production of a system of hydroplants by minimizing losses in turbines and waterways, while maintaining production to meet load. The problem is inherently of the mixed integer nonlinear type, but an algorithm has been developed to solve it in two stages by linear programming (LP). The model has been tested with data from an existing purely hydroelectric system, the Icelandic power system being the model system. Results indicate considerable savings in water usage from large seasonal reservoirs. These results also indicate the feasibility of installing the model in a control center computer when conditions are similar to the model system. >

Defining optimal production capacity in a purely hydroelectric power system

The conventional definition of system and plant firm capacity, in a thermally dominated power system, is often simply the installed MW adjusted by plant availability. A hydro dominated system requires an entirely different and expanded definition due to the complex interactions resulting from temporal reservoir operational decisions. In this paper several economic definitions of capacity are presented and analyzed based on the need for this concept in the operation and expansion of hydro dominated systems.

Iceland's Energy Resources and Master Plan with Environmental and Economic Constraints

The Icelandic Master plan (MP) for evaluating renewable energy resources was initiated by the Government of Iceland in 1999 and is currently in its Phase 2 stage, here called MP2. MP2 is at the time of writing, under review by the Iceland Parliament (Alþingi) waiting to be passed as law and is subject to environmental and economic scrutiny. The MP2 continued the effort of MP1 of assessing the country’s hydroelectric and geothermal energy resources but with the emphasis on preservation vs. utilization. Other renewable energy resources, such as wind and solar, have not been estimated in the MP. The energy resources and progress in their evaluation in the MP is reviewed and summarized and results and conclusions are drawn regarding these indigenous energy resources, as seen in the MP2. The paper sets forth an updated view of the scope and limits of the viable energy resources in terms of hydro and geothermal resources and projects to be harnessed in the future for local utilization and export.

The Economic Rent in hydro and geothermal resources in iceland with reference to international energy markets and resource cost structure

In this paper the concept of economic rent (ER) is reviewed and applied to the virtually emission-free renewable energy resources of Iceland. In particular, a case study is presented with experimental test data from the Icelandic hydro and geothermal system. A calculation is presented based on prices in the domestic and an international market as well as cost assumptions. The importance of the ER concept is of particular interest in a case where the electric power system utilizes renewable energy resources to the greatest extent of almost any country in the world. For this reason the Iceland energy situation should be of special interest, where no fossil fuel resources are available and where fuel-based electricity generation is virtually non-existent. The results of the paper include a case study suggesting the economic significance of renewable natural energy resources in the form of ER. A pilot numerical example is presented to lead the way for further appraisal of the economic value of these resources with a more developed data set and cost assumptions.

Electric load forecasting in a hydro- and renewable based power system

Electric load forecasting has for decades been an integral part of power system planning, including renewable hydro based system planning. In this paper we present load forecasting in the renewable based power system of Iceland. When load forecasting was initiated, informal forecast were made by utility companies, especially before and after establishing the main generating company, Landsvirkjun in 1965. However, in 1976, a dedicated Energy Forecasting Committee (EFC) was established by the stakeholders to carry out coordinated, system wide forecasts of annual electric load. The paper reviews the history and practice in these forecasts and, in addition, adapts them to renewable system needs, by expanding them to include different time frames, and suitable calendars for annual, weekly and hourly system wide time frames. This is done by interpolation in weekly and season-specific hourly distribution factors, from generic factors published and estimated by the EFC. The results of this paper include a load forecasting framework, applicable in three time frames and various types of power system planning and operations models. The modeling approach presented here constitutes a coordinated hierarchy with annual load forecasts at the top, then a medium term weekly model and a short term, hourly load model at the bottom of the hierarchy. These modeling approaches can be used interactively in power system modular planning and operations models.

Computerisation of the Icelandic State and Municipalities

The paper relates how some key IT applications developed in Iceland following the introduction of the first computers in 1964. The key applications treated are the National Register of Persons, real estate assessment, financial systems, centralised processing of bank checks, fish stock abundance computations, IT in fish processing plants, the control of hydroelectric power stations, and the challenge of adopting the Icelandic alphabet to the use of computers.

Accumulation of a resource fund for Iceland's renewable energy resources

The Icelandic electrical energy resources are primarily based on hydroelectric and geothermal electricity generation. At present wind energy generation is negligible but has a certain potential for the future, in particular considering the synergy of wind generation and hydro reservoirs. Iceland has large resources compared to the size of its island economy and with only about 350 thousand inhabitants the amount of energy resources per capita is among the highest in the world for any country. However, as the power system is presently isolated from any larger electricity markets, it is difficult to realize the potential economic benefit or rent of these resources. This rent may to some extent, due to market circumstances, be “locked in” with local utilization such as energy intensive industry. A future interconnector [2] may, however, link to established markets with energy prices independent of these circumstances and renewable energy prices in these markets may be rising in the future rather than declining.

Optimal long term hydro scheduling linked to average electricity market prices

Traditionally, the Icelandic, island, hydro-based power system has been scheduled and planned based on local, isolated demand of two types: General Demand (GD) and the flat, now dominating Energy Intensive Industry (EII) demand. Thus a local load profile determines the scheduled operation, perhaps causing underutilization of resources, and water spillage. This limited flexibility is built into an isolated system, but interruptible EII contracts have served to increase the utilization to better meet the variable resource inflow (Water, geothermal steam). However, an access to a larger market would mitigate and change radically this limitation. Therefore a model based estimate of possible benefits is all important, when considering a UK-Iceland HVDC submarine link. This paper compares the optimal scheduling of a test system based on the Iceland system, with and without an external submarine link to a larger electricity market. A model HYDW1 uses linear programming (LP) and CPLEX to simulate weekly operations, using an official long term load forecast. This test system uses historical weekly averaged UK electricity spot prices and assumes a submarine link with preliminary cost estimates. The results quantify the benefits of trading flexible water power in a spot market, in terms of energy sales and operations costs by better utilizing the installed capacity, water flow and reservoirs. Finally, conclusions are drawn on expanding the weekly HYDW1 model to encompass a short term extension to enhance the future planning framework.

Optimal hydroelectric and geothermal project sequencing and sizing with dynamic programming

The project sequencing problem with, for instance, hydroelectric or geothermal projects of fixed sizes, has been addressed using techniques such as Dynamic Programming (DP) and heuristics. This involved choosing a permutation sequence of projects, out of N! = N! (N −1),…,2 · 1 possible permutation sequences, to minimize total cost. Here, the problem of sequencing and sizing using a DP search algorithm is addressed with discrete sizing options added, which however expands the search space immensely. The DP method, however, dramatically saves computation time compared to exhaustive enumeration of the search space, and results in an globally optimal sequence and size of projects, given a set of projects with discrete sizing alternatives and other assumptions. The method is tested a data set and, in addition, assumes a given demand function and long range marginal cost (LRMC) of a back-up supply. This supply is assumed to be used after all hydroelectric or renewable energy resources or projects have been exhausted to satisfy the demand. The method has practical applications, for instance in the screening process for selecting and designing resource expansions of discrete projects in the field of renewable energy resources.

Stream-flow capacity shaved energy distribution in hydroelectric power systems

The seasonal flow distribution into a hydroelectric system is analyzed, without considering reservoirs, in terms of time series for lateral energy inflows and internal flows at generating facilities. Key concepts, such as regulated and unregulated flow are defined and illustrated, in addition to peak shaving energy inputs based on station installed capacities. Therefore spilled energy is compared to usable energy, considering the installed capacities and the resulting time series are analyzed and illustrated graphically. We are primarily interested in the temporal distribution and variations, without considering the impact of any seasonal reservoirs to correct the discrepancies between inflow and outflow. Thus the shapes of the flow series, when aggregated for instance into regulated and unregulated flow is analyzed with a simple vector/matrix-based model. A case study based on conditions in the Icelandic hydro-based power system is also presented.