An Off-design Thermoeconomic Input-Output Analysis of a Natural Gas Combined Cycle Power Plant

In the current and forecasted energy scenario, Natural Gas Combined Cycle (NGCC) power plants are requested increasingly flexible operation. The continuous changes in the capacity factor of the power plants and the increasing number and steepness of ramp-ups could largely affect the thermodynamic and economic performance of the plants and undermine their competitiveness. In order for industrial operators to adopt competitive strategies to increase the flexibility of the power plants, the effect that off-design operation has on the cost structure of plant products needs to be addressed. Thermoeconomics provides tools and models to meet such objective. The study presents an application of Thermoeconomic Input-Output Analysis (TIOA) to a NGCC power plant subject to flexible operation in Italy. The on- and off-design performance of the plant is assessed, considering two load control mechanisms for off-design operation: Inlet Guide Vanes (IGVs) with constant Turbine Outlet Temperature (TOT) or constant Turbine Inlet Temperature (TIT). The Input-Output model is derived from a detailed off-design Thermodynamic model designed in Thermoflow Thermoflex™, and it is stand-alone: it computes the cost structure of the plant products and the Thermoeconomic performance indicators as continuous functions of the gas turbine load, independently from the Thermodynamic model. In the first place, the on- and off-design models of the plant are set up. Secondly, the detailed economic cost analysis is performed. Eventually, the stand-alone Input -Output model is derived: the Technical Coefficients and the Input Coefficients are computed from the fuels and products in the Thermodynamic model at different loads; by regression of the obtained values, continuous functions of the load are derived for each coefficient; finally, the stand-alone model is designed, including these functions in the Leontief Inverse matrix. The results provide an evaluation of the off-design performance of the power plant for the two control strategies, and a tool for the choice of the most efficient one. After specialised analysts set up and run the off-design Thermodynamic model, the power plant operators may perform production scenarios and predictions through the stand-alone Input-Output model independently. This may help abate barriers for industrial practitioners, given by the complexity, computational effort and difficult interpretation of off-design thermodynamic and cost models

PRACTICAL APPROACHES FOR THE APPLICATION OF EXERGY COST THEORY TO ENERGY CONVERSION SYSTEMS

The Exergy Cost Theory (ECT) was proposed as a complete and formalized method to account for the exergy cost of system products, defining criteria for optimization and diagnosis purposes. In this paper, different practical approaches for the application of the Exergy Cost Analysis are presented and comparatively applied to the CGAM problem. An emphasis has been specially put on the possible approaches to define and to solve the system of exergy cost balances, including the definition of auxiliary relations and the reallocation of the exergy cost of residues. It is found that the definition of the functional diagram and the numerical solution of the system through Input-Output analysis seems to be preferable with respect to other approaches

Off-Design Modeling of Natural Gas Combined Cycle Power Plants: An Order Reduction by Means of Thermoeconomic Input–Output Analysis

In a European context characterized by growing need for operational flexibility across the electricity sector, the combined cycle power plants are increasingly subjected to cyclic operation. These new operation profiles cause an increase of production costs and decrease of revenues, which undermines the competitiveness of the combined cycles. Power plant operators need tools to predict the effect of off-design operation and control mechanisms on the performance of the power plant. Traditional Thermodynamic or Thermoeconomic models may be unpractical for the operators, due to their complexity and the computational effort they require. This study proposes a Thermoeconomic Input–Output Analysis model for the on- and off-design performance prediction of energy systems, and applies it to La Casella Natural Gas Combined Cycle (NGCC) power plant, in Italy. It represents a stand-alone, reduced order model, where the cost structure of the plant products and the Thermoeconomic performance indicators are derived for on- and off-design conditions as functions of the load and of different control mechanisms, independently from the Thermodynamic model. The results of the application show that the Thermoeconomic Input–Output Analysis model is a suitable tool for power plant operators, able to derive the same information coming from traditional Thermoeconomic Analysis with reduced complexity and computational effort

Long-term energy planning and demand forecast in remote areas of developing countries: Classification of case studies and insights from a modelling perspective

More than half a billion people will still lack reliable and affordable electricity in 2040 and around 1.8 billion may remain reliant on traditional solid biomass for cooking. Long-term energy planning could help to achieve the energy access targets in developing countries, especially in remote rural areas. Different studies exist on long-term rural electricity and thermal energy planning, but the different foci, terminology and methodologies make it difficult to track their similarities, weaknesses and strengths. With this work, we aim at providing a critical analysis of peer-reviewed studies on long-term rural energy planning, to help researchers in the field move across the diverse know-how developed in the last decades. The work resulted in the analysis of 130 studies and categorisation of 85 of them that focus on electricity, thermal energy, and oil supply in rural areas, under a number of rules clearly defined in the first part of the paper. We classify the studies in two consecutive steps, first according to their type and afterwards according to the methodology they employ to forecast the energy demand, which is one the most critical aspects when dealing with long-term rural energy planning. The work also provides specific insights, useful to researchers interested in rural energy modelling. Few studies assume a dynamic demand over the years and most of them do not consider any evolution of the future energy load, or forecast its growth through arbitrary trends and scenarios. This however undermines the relevance of the results for the purpose of long-term planning and highlights the necessity of further developing the forecasting methodologies. We conclude that bottom-up approaches, system-dynamics and agent-based models seem appropriate approaches to forecast the evolution of the demand for energy in the long-term; we analyse their potential capability to tackle the context-specific complexities of rural areas and the nexus causalities among energy and socio-economic dynamics

The role of Energy-Water nexus to motivate transboundary cooperation:: An indicative analysis of the Drina River Basin

Hydropower is a key energy source for achieving Sustainable Development Goal 7. Meanwhile, the effects of hydropower development and operation are complex, and potentially a source of tension on transboundary rivers. This paper aims at exploring solutions that consider both energy and water to motivate transboundary cooperation in the operation of hydropower plants (HPPs) in the Drina River Basin (DRB), where the level of cooperation among the riparian countries is low. OSeMOSYS was used to develop a multi-country model with a simplified hydrological system to represent the cascade of HPPs in the DRB. Results show that improved cooperation can increase electricity generation in the HPPs downstream without compromising generation upstream. It also demonstrates the role of inexpensive hydropower in enhancing electricity trade in the region. Implementing energy efficiency measures would reduce the stress on coal power plants, which will mitigate CO2 emissions by about 21% compared to the 2015 level

From the development of an open-source energy modelling tool to its application and the creation of communities of practice: The example of OSeMOSYS.

In the last decades, energy modelling has supported energy planning by offering insights into the dynamics between energy access, resource use, and sustainable development. Especially in recent years, there has been an attempt to strengthen the science-policy interface and increase the involvement of society in energy planning processes. This has, both in the EU and worldwide, led to the development of open-source and transparent energy modelling practices. This paper describes the role of an open-source energy modelling tool in the energy planning process and highlights its importance for society. Specifically, it describes the existence and characteristics of the relationship between developing an open-source, freely available tool and its application, dissemination and use for policy making. Using the example of the Open Source energy Modelling System (OSeMOSYS), this work focuses on practices that were established within the community and that made the framework's development and application both relevant and scientifically grounded

Addressing Challenges in Long-Term Strategic Energy Planning in LMICs: Learning Pathways in an Energy Planning Ecosystem

This paper presents an innovative approach to addressing critical global challenges in long-term energy planning for low- and middle-income countries (LMICs). The paper proposes and tests an international enabling environment, a delivery ecosystem, and a community of practice. These components are integrated into workflows that yield four self-sustaining capacity-development outcomes. Planning long-term energy strategies in LMICs is particularly challenging due to limited national agency and poor international coordination. While outsourcing energy planning to foreign experts may appear to be a viable solution, it can lead to a reduction in government agency (the ability of a government to make its own informed analysis and decisions). Additionally, studies commissioned by external experts may have conflicting terms of reference, and a lack of familiarity with local conditions can result in misrepresentations of on-the-ground realities. It is argued here that enhancing national agency and analytical capacity can improve coordination and lead to more robust planning across line ministries and technical assistance (TA) providers. Moreover, the prevailing consulting model hampers the release and accessibility of underlying analytics, making it difficult to retrieve, reuse, and reconstruct consultant outputs. The absence of interoperability among outputs from various consultants hinders the ability to combine and audit the insights they provide. To overcome these challenges, five strategic principles for energy planning in LMICs have been introduced and developed in collaboration with 21 international and research organizations, including the AfDB, IEA, IRENA, IAEA, UNDP, UNECA, the World Bank, and WRI. These principles prioritize national ownership, coherence and inclusivity, capacity, robustness, transparency and accessibility. In this enabling environment, a unique delivery ecosystem consisting of knowledge products and activities is established. The paper focuses on two key knowledge products as examples of this ecosystem: the open-source energy modeling system (OSeMOSYS) and the power system flexibility tool (IRENA FlexTool). These ecosystem elements are designed to meet user-friendliness, retrievability, reusability, reconstructability, repeatability, interoperability, and audibility (U4RIA) goals. To ensure the sustainability of this ecosystem, OpTIMUS is introduced—a community of practice dedicated to maintaining, supporting, expanding, and nurturing the elements within the ecosystem. Among other ecosystem elements, training and research initiatives are introduced, namely the Energy Modelling Platform for Africa, Latin America and the Caribbean, and Asia-Pacific as well as the ICTP Joint Summer School on Modelling Tools for Sustainable Development. Once deployed via workflows, the preliminary outcomes of these capacity-development learning pathways show promise. Further investigation is necessary to evaluate their long-term impacts, scalability, replication, and deployment costs

Assessing the impact of applying individual discount rates in power system expansion of Ecuador using OSeMOSYS

The development of the electricity supply sector needs data and energy system models to aid government instances to achieve optimal decision-making. Since 2006, Ecuador has faced gradual changes in the electricity sector and invested more than 11 billion dollars in expanding the generation. We use an open-source model generator in the present study and develop the first long-term generation expansion model for Ecuador. We select specific social and hurdle rates to represent the government's decision to mobilize private energy infrastructure investments. We build scenarios for social and hurdle rates to evaluate the sensitivity of renewable and conventional generation technologies to such rates. Results show that medium and large hydropower have a low sensitivity to discount rates. Medium and large hydropower plays a significant role in the energy mix in the mid and long-term, regardless of the discount rate. Results from this model find no significant contribution of non-hydro renewables. Among these, only geothermal reaches around 160 MW for all scenarios. Installing geothermal and hydropower minimizes generation from conventional technologies until 2034; then, CCGT installations increase CO2 emissions above 2020 levels

Comprehensive representation of models for energy system analyses: Insights from the Energy Modelling Platform for Europe (EMP-E) 2017

This article discusses different approaches that are used to present and categorise models used in energy system analysis, with the overall objective to improve their quality, efficiency, and outreach to policy makers and public stakeholders involved in the European energy transition. A comprehensive literature review identifying strengths and limitations of existing approaches of classification is conducted. It highlights the tendency towards a versatile presentation of models, where the same set of information is available for all users while the way it is presented can be customised according to the background and interests of several stakeholder groups (e.g., modellers, researchers in the energy field, policy advisers, and policy makers). Online platforms enhance this concept by allowing dynamic adaptations. We think that improving this approach could be a potentially significant contribution to the scientific work in the field of energy system analysis. In addition to the literature review, we include experiences from the first meeting of the Energy Modelling Platform for Europe (EMP-E 2017). The participants used different formats to present their models. In the open space provided, the trade-off between simplicity and completeness of representation was visible. Feedback of the meeting showed that gathering European modellers and policy makers in a personal meeting is valuable as it motivates and improves exchange between modelling groups and between modellers and those stakeholders who are interested in specific results. Keywords: Energy system modelling, Model categorisation, Model collection, Exchange between stakeholder

The Open Source electricity Model Base for Europe - An engagement framework for open and transparent European energy modelling

The transition to a low carbon energy system as laid out in the Paris Agreement and the European GreenDeal presents challenges that involve society at all levels from planners to consumers. A key challenge isthe communication across these levels. Tools to foster engagement and discussion between the differentactors are open-source models with a low threshold for uptake. This paper presents the Open-Sourceelectricity Model Base for Europe an electricity sector engagement model covering all member statesof the EU, Norway, Switzerland and the United Kingdom. Built in OSeMOSYS and available on GitHub, themodel provides a starting point into energy systems modelling and can be further developed in acollaborative manner. It enables non-experts to develop an understanding of energy systems models andenergy planning. Thereby, it can serve as an engagement tool to carry the debate on the future of theEuropean power system beyond the academy, which might contribute to finding societal consensus onhow to decarbonise our energy system. The model allows dynamic power sector expansion analysis ofthe European power system till 2050. It can be used for scenario analysis and is expandable to othersectors to analyse the benefits of sector coupling.QC 20211028</p