Energy Storage Systems

Transcription

1 Ene Energy System for Communities Emerging technologies in energy systems for cities & urban areas Energy Storage Systems Nusrat Jung Topic of Today Urban Community Consumption Heating & Cooling Forecasting Transportation Electricity Planning Energy Technology & Infrastructure Methods Wind Energy Life Cycle Assesment Power Distribution Solar Energy Micro Co-Generation Heat Pumps Biomass Utilization District Heating Storage Systems 1

2 Indispensable elements of the energy revolution Shift in Energy policy Increasing volume of solar & wind energy- need to be evened out and matched to consumption for stable power supply Success of renewables creates a new problem: Need to absorb immediate surplus power 2025: Pumped and compressed air storage systems and storage power stations can offer short-term storage 2040: It will be necessary to store electricity for several weeks & months Why solutions are needed Stochastic fluctuations: periods btw several days and weeks at a time. Power consumption follows a characteristic pattern Grid does not store electricity: Load management actively balancing the power being fed in with the power being consumed* * Limited to static central electricity storage systems linked to the grid. Concept for portables varies 2

3 Technical and economical advantages of energy storage systems Energy Transfer -Convention energy storage could compensate for temporary loss of production of generating unit. -fulfil commercial obligation of pre-sold energy supply/avoid penalties -renewable: add value to supply current (e.g.: delivery of electrical power during peak hours) Network savings -Ratio btw peak & average power often reaches a value of 10 leading to over-dimensioning of production & transmission equipment (peak) The kinetic advantage -Resulting gains due to storage systems need to secure a return on of the double conversion chain Electricity storage systems 3

4 Electricity storage systems Worldwide installed storage capacity About 3 % of global generation capacity. Source: 4

5 Source: ; last accessed on

6 Background Small scale systems -Low-power application in isolated areas to feed transducers and emergency terminals -Medium power application in isolated areas - Kinetic energy, thermal energy, chemical energy, compressed air, hydrogen as fuel cell, super capacitor or super conductors Large scale systems - Network connection application with peak levelling - Power quality control applications - Where it can be stored as gravitational energy (hydraulic system) Pumped Hydro Storage (PHS) Readily available, uses water Mostly used for high-power applications (100 of MW) Essential components Pumped storage sub-transmission station Site Principle Low demand period - use electricity to pump water High demand period activate turbines to generate high-value electricity 6

7 Pumped Hydro Storage (PHS) Source: Storage capacity : height of water fall and volume of water (ratio) Mass of 1 ton falling 100m generates kwh Example: Pumped hydroelectric reservoirs in Pennsylvania, USA 435-MW hydroelectric power plant, generating power to supply demand for electricity, or as a pumped storage facility. Energy management and load leveling services while advantage of differences in the wholesale price of electricity over the course of the day or the week. 7

8 Thermal Energy Storage (TES) 1. Sensible Heat Storage (SHS): heating bulk material that does not change state (sodium, molten salt, pressurised water) during the accumulation phase. -heat is then recovered to produce water vapour-> drives a turboalternator system 1. Latent-fusion-heat (LHS): liquid-solid transition of material at constant temperature (sodium hydroxide/highly corrosive) - During accumulation phase the bulk material -> solid state to liquid-> heat transfer btw the accumulator and the exterior environment (heat transfer fluid)->higher the heat/higher the concentration->fusion enthalpy grows Thermal Energy Storage (TES), Sensible Heat Storage 200 Water tight cisterns Thémis station in France : Use of molten salt with solar panels Stores 40,000 kwh of thermal energy/ 1 day of avg. sunlight in 550 tons of fused electrolyte 8

9 Thermal Energy Storage (TES), Sensible Heat Storage -Hot water storage (200) -Off peak hours, HWS can be obtained from a thermal plant -Condensation of the high pressure steam from the boiler or by tapping at low temperature from turbine outlet Fig: sensible heat storage of electricity in a power plant -Thermal storage reservoir designed for 1000 kwh, 20m dia, 20m height for volume of 5000m 3 Compressed Air Energy Storage (CAES) Concept Relies on mature technology with several high power projects in place Power plant with standard gas turbine-2/3 of available to compress the combustion air Separating the process in time to use electrical power during offpeak hours (storage hours) To compress the air, then produce during peak hours (retrieval hours) 3 times the power for same fuel consumption by expanding air in combustion chamber before feeding in turbines 9

10 Compressed Air Energy Storage (CAES) To release 1kWh into network, kwh of electricity need to be absorbed during off-peak hours to compress air as well as 1.22 kwh of natural gas during peak hours (retrieval). --Self-discharge (air-leak) to be absolute minimum --Benefit from geostatic pressure facilitating containment of the air mass Example: Adiabatic Compressed-Air Energy Storage Please use the following link to see the video presented in lecture 1: RWE Power: ADELE - Adiabatic compressed-air energy storage 2: Pumped Hydro Storage: 10

11 Energy storage coupled with Natural Gas Storage (NGS) Concept Couple underground natural gas storage with electricity storage Pressure difference btw high-pressure gas storage (200 bars) in reservoirs deep underground (1500m) AND Gas injected into the conduits with a maximum service pressure of bars Leads to consumption of energy for compression, which could be released in the form of electricity during decompression Energy storage coupled with Natural Gas Storage (NGS) Essential components: Two storage reservoirs for liquefied natural gas and liquid air, regenerative heat exchangers, a compressor, and a gas turbine Burning of natural gas to activate the turbine and generate electricity, the liquid and the gas are vaporised and cold (conserved in exchangers) Off peak hour Air is cooled by stored air Compressed with electric compressor Liquefied Stored 11

12 Many more Chemical storage Energy Storage using Flow Batteries (FBES) Flywheel Energy Storage (FES) Fuel cells-hydrogen energy storage (FC-HES) Small-scale compressed air energy storage (SSCAES) Energy storage in super capacitors Superconducting magnetic energy storage (SMES) Characteristics of energy storage techniques 12

13 Characteristics of energy storage techniques Classified by Type of application: permanent or portable Storage duration: short or long Type of production: Maximum power needed Necessary to analyse the fundamental characteristics Characteristics of energy storage techniques Storage capacity- quantity of available energy in the storage system after charging Available power- constitution and size of the motor-generator in the stored energy conversion chain Depth of discharge or power transmission rate- delivery rate determines the time needed to extract the stored energy Discharge time-max power discharge duration/system adequacy Efficiency (ratio btw released energy & stored) Durability (cycling capacity) Autonomy-max amount of times system can release energy Costs/Feasibility&adaptation to the generating source 13

14 Characteristics: Feasibility and adaptation to the generating source Characteristics of energy storage techniques Self-discharge Mass and volume densities of energy Monitoring and control equipment Operational constraints Reliability Environmental aspect Other etc. 14

15 Comparison of the different storage techniques Comparison of Technical Parameters of Energy Storage Technologies Source: 15

16 Status of technology development Comparison of the investment cost per charge-discharge cycle 16

17 Conclusions For low-power permanent applications: lowest possible self-discharge For small systems (few kwh): Autonomy; Lead battery For Large systems (few 100kWh): Lead is preferred - compressed air (self discharge problems) - fuel cells (expensive and low energy efficient) - flow batteries (high maintenance cost) Peak hour load levelling requiring high-energy storage: compressed air and flow batteries Power quality: lead batteries (fuel cells are still new) Future needs On delocalised production:- Need of improved technologies on short to mid-term Lithium-ion batteries are very performent, expensive Recycling and waste management of batteries Life expectancy for lead batteries, weak link in isolated systems For network application:- Mid-term needs are ever growing Flow batteries, compressed air, super capacitors & flywheel to be made cost effective, reliable and efficient 17

18 Storage is the weakest link of energy domain, but is the key element for the growth of renewable energies Discussions 18

19 What have we learned? The technical and economical advantages of energy storage Kinds of electricity storage systems with there main components, and how they function. Classification for characteristics of energy storage systems. characteristics:- storage capacity, efficiency, durability and monitoring and control equipment etc. Source articles 1: H. Ibrahim, A. Ilincaa, J. Perron, Energy storage systems Characteristics and comparisons. 2: Y.S. Mohammeda,n, M.W. Mustafa a, N. Bashir b, Hybrid renewable energy systems for off-grid electric power: Review of substantial issues 19