Increasing the Flexibility of Combined Heat and Power Plants With Heat Pumps and Thermal Energy Storage

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Eike Mollenhauer ◽  
Andreas Christidis ◽  
George Tsatsaronis
Keyword(s):  
Thermal Energy ◽  
Electricity Market ◽  
Power Plants ◽  
Combined Heat And Power ◽  
Heat Pumps ◽  
Optimal Operation ◽  
Mixed Integer ◽  
Steam Turbines ◽  
Mixed Integer Linear Program ◽  
District Heating System

Combined heat and power (CHP) plants are efficient regarding fuel, costs, and emissions compared to the separate generation of heat and electricity. Sinking revenues from sales of electricity due to sinking market prices endanger the economically viable operation of the plants. The integration of heat pumps (HP) and thermal energy storages (TESs) represents an option to increase the flexibility of CHP plants so that electricity can be produced only when the market conditions are favorable. The investigated district heating system is located in Germany, where the electricity market is influenced by a high share of renewable energies. The price-based unit-commitment and dispatch problem is modeled as a mixed integer linear program (MILP) with a temporal resolution of 1 h and a planning horizon of 1 yr. This paper presents the optimal operation of a TES unit and a HP in combination with CHP plants as well as synergies or competitions between them. Coal and gas-fired CHP plants with back pressure or extraction condensing steam turbines (STs) are considered, and their results are compared to each other.

scholarly journals Integration of Flow Temperatures in Unit Commitment Models of Future District Heating Systems

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1061 ◽  
Author(s):  
Cynthia Boysen ◽  
Cord Kaldemeyer ◽  
Simon Hilpert ◽  
Ilja Tuschy
Keyword(s):  
Technology Assessment ◽  
Power Plants ◽  
Internal Combustion Engines ◽  
Unit Commitment ◽  
District Heating ◽  
Heat Pumps ◽  
Combined Cycle ◽  
Mixed Integer ◽  
District Heating System ◽  
Temperature Levels

The transformation of heat supply structures towards 4th generation district heating (4GDH) involves lower supply temperatures and a shift in technology. In order to assess the economic viability of the respective systems, adequate unit commitment models are needed. However, maintaining the formal requirements, while reducing the computational efforts of these models, often includes simplifications such as the assumption of constant supply temperatures. This study investigates the effect of introducing varying supply temperatures in mixed-integer linear programming models. Based on a case study of a municipal district heating system, how the temperature integration approach affects unit commitment and technology assessment for different temperature levels and scenarios is analyzed. In particular, three supply temperature levels are investigated with both variable and constant temperatures in two scenarios. Results indicate that lower flow temperature levels in the heating network tend to favor internal combustion engines, combined cycle power plants, and heat pumps; while back pressure steam turbines, peak loads, and electric boilers show declining operating hours. Furthermore, the effect of varying versus constant temperatures at the same temperature level is rather small, at least as long as technical restrictions do not come into play. Finally, it is found that the effect of changing temperature on a technology assessment is comparably small as opposed to adaptions in the regulatory framework.

Optimization of Thermal Power Plants Operation in the German De-Regulated Electricity Market Using Dynamic Programming

2012 ◽  
Author(s):  
G. Scarabello ◽  
S. Rech ◽  
A. Lazzaretto ◽  
A. Christidis ◽  
G. Tsatsaronis
Keyword(s):  
Electricity Market ◽  
Power Plants ◽  
Thermal Power ◽  
Optimal Operation ◽  
Renewable Energies ◽  
Combined Cycle ◽  
Mixed Integer ◽  
Programming Approach ◽  
Thermal Power Plants ◽  
Spot Prices

The prospect of clean electrical energy generation has recently driven to massive investments on renewable energies, which in turn has affected operation and profits of existing traditional thermal power plants. In this work several coal-fired and combined cycle power units are simulated under design and off-design conditions to adequately represent the behavior of all modern thermal units included in the German power system. A dynamic optimization problem is then solved to estimate the short-run profits obtained by these units using the spot prices of the German electricity market (EEX) in years 2007–2010. The optimization model is developed using a Mixed Integer Linear Programming approach to take the on-off status into account and reduce computational effort. New market scenarios with increasing renewable shares (and consequently different spot prices) are finally simulated to analyze the consequences of a larger capacity of renewable energies on the optimal operation of traditional thermal power plants.

scholarly journals Investment Incentives in Competitive Electricity Markets

2018 ◽  
Vol 8 (10) ◽  
pp. 1978 ◽  
Author(s):  
Jaber Valinejad ◽  
Taghi Barforoshi ◽  
Mousa Marzband ◽  
Edris Pouresmaeil ◽  
Radu Godina ◽  
...  
Keyword(s):  
Electricity Markets ◽  
Electricity Market ◽  
Planning Horizon ◽  
Optimization Method ◽  
Design Criterion ◽  
Mixed Integer ◽  
Investment Incentives ◽  
Mixed Integer Linear Program ◽  
Interconnected Power System ◽  
The Impact

This paper presents the analysis of a novel framework of study and the impact of different market design criterion for the generation expansion planning (GEP) in competitive electricity market incentives, under variable uncertainties in a single year horizon. As investment incentives conventionally consist of firm contracts and capacity payments, in this study, the electricity generation investment problem is considered from a strategic generation company (GENCO) ′ s perspective, modelled as a bi-level optimization method. The first-level includes decision steps related to investment incentives to maximize the total profit in the planning horizon. The second-level includes optimization steps focusing on maximizing social welfare when the electricity market is regulated for the current horizon. In addition, variable uncertainties, on offering and investment, are modelled using set of different scenarios. The bi-level optimization problem is then converted to a single-level problem and then represented as a mixed integer linear program (MILP) after linearization. The efficiency of the proposed framework is assessed on the MAZANDARAN regional electric company (MREC) transmission network, integral to IRAN interconnected power system for both elastic and inelastic demands. Simulations show the significance of optimizing the firm contract and the capacity payment that encourages the generation investment for peak technology and improves long-term stability of electricity markets.

Sizing of a Gas Turbine for Repowering of Cogeneration Power Plant Ljubljana by Mathematical Optimisation

1996 ◽  
Author(s):  
Mihael Gabriel Tomšič ◽  
Olgica Perović
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Optimal Operation ◽  
Hot Water ◽  
Mixed Integer ◽  
Heat Recovery Boiler ◽  
Continuous Variables ◽  
District Heating System ◽  
Operational Strategy ◽  
Steam Extraction

The paper deals with optimal sizing of a gas turbine for repowering of cogeneration power plant Ljubljana considering possible plant operational strategy with respect to variations of electric and heat loads and energy costs. CHP plant is a main source for the Ljubljana town district heating system. Existing plant consists of two condensing steam turbines with steam extraction, back pressure turbine with steam extraction, auxiliary steam and hot water boilers for peak heat load production. This system delivers up to 111 MW into the power grid and up to 348 MW of heat. Repowering with gas turbine generator set with additionally fired heat recovery boiler is considered. For uncoupling heat and power generation a heat storage tank is assumed. For sizing of new equipment and plant operational strategy a model based on mixed-integer linear programming was developed. Zero - one integer variables are adopted to indicate the on/off status of operation, continuous variables to indicate the operational level of each constituent equipment and an optimal solution is derived by branch and bound method. Two prospective sizes of TG sets were tested for range of assumptions regarding power purchase tariff schedules. Different optimal operation policies resulted. The study provides background for contract negotiation and for investment decisions.

Cost Optimal Strategies of High Temperature Thermal Energy Storage Systems in Combined Heat and Power Applications

2016 ◽  
Author(s):  
Parker Wells ◽  
Karthik Nithyanandam ◽  
Richard Wirz
Keyword(s):  
High Temperature ◽  
Energy Storage ◽  
Los Angeles ◽  
Natural Gas ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Power Plants ◽  
Combined Heat And Power ◽  
Time Of Day ◽  
Recycled Paper

As variable generation electricity sources, namely wind and solar, increase market penetration, the variability in the value of electricity by time of day has increased dramatically. In response to increase in electricity demand, natural gas “peaker plants” are being added to the grid, and the need for spinning and nonspinning reserves have increased. Many natural gas, and other heat source based, power plants exist as combined heat and power (CHP), or cogeneration, plants. When built for industrial use, these plants are sized and run based on heat needs of an industrial facility, and are not optimized for the value of electricity generated. With the inclusion of new, less expensive thermal energy storage (TES) systems, the heating and electricity usage can be separated and the system can be optimized separately. The use of thermal energy storage with CHP improves system economics by improving efficiency, reducing upfront capital expenditures, and reducing system wear. This paper examines the addition of thermal energy storage to industrial natural gas combined heat and power (CHP) plants. Here a case study is presented for a recycled paper mill near Los Angeles, CA. By implementing thermal energy storage, the mill could decouple electric and heat production. The mill could take advantage of time-of-day pricing while producing the constant heat required for paper processing. This paper focuses on plant economics in 2012 and 2015, and suggests that topping cycle industrial CHP plants could benefit from the addition of high temperature (400–550°C) energy storage. Even without accounting for the California incentives associated with implementing advanced energy storage technologies and distributed generation, the addition of energy storage to CHP plants can drastically reduce the payback period below the 25 year expected economic lifetime of a plant. Thus thermal energy storage can make more CHP plants economically viable to build.

Active and Passive Thermal Energy Storage in Combined Heat and Power Plants to Promote Wind Power Accommodation

2017 ◽  
Vol 143 (5) ◽  
pp. 04017037 ◽  
Author(s):  
Yuanhang Dai ◽  
Lei Chen ◽  
Yong Min ◽  
Qun Chen ◽  
Yiwei Zhang ◽  
...  
Keyword(s):  
Energy Storage ◽  
Wind Power ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Power Plants ◽  
Combined Heat And Power
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