The demand for energy storage in regenerative energy systems

Transcription

1 The demand for energy storage in regenerative energy systems First International Renewable Energy Storage Conference (IRES I) Gelsenkirchen, October, 30 th /31 st 2006 Dirk Uwe Sauer Electrochemical Energy Conversion and Storage Systems Group Institute for Power Electronics and Electrical Drives (ISEA) RWTH Aachen University / Germany Power generation and consumption must be in equilibrium at any time, otherwise... Imbalance amongst power generation and consumption immediately results in a drop of voltage or in overvoltage. Both events activate protection systems resulting in a shut down of appliances or grid segments. No 2

2 Blackout in Italy during night ( , 4:00 a.m.) Increasing renewable energy penetration requires energy storage capacity Source: IAEW, Prof. Haubrich No 3 Power generation and consumption must be in equilibrium at any time, otherwise... Imbalance among power generation and consumption immediately results in a drop of voltage drop or in overvoltage. Both activates protection systems resulting in a shut down of appliances of grid segments. Storage systems with very fast response times, high power capability and sufficient energy reserve are required. No 4

3 Actual electricity rates (Energy Stock Exchange), Germany ,0 20,0 Time / Hours Euro Cent / kwh 17,5 15,0 12,5 10,0 7,5 5,0 Source: Fritz Crotogino, KBB Hannover Time / Days 2,5 No 5 Outline Definition of a storage system Highly fluctuating power generation from renewable energies Transmission lines vs. storage systems Autonomous power supply systems Demand for heat storage systems Storage technologies Typical power and energy range for various applications and storage technologies Conclusions No 6

4 Definition of a storage system for electrical energy defines charging power defines energy capacity defines discharging power charging of storage discharging of storage electrical energy converter. energy storage converter electrical energy Batteries / Supercaps: integrated device Compressed air storage: compressor cavern, heat storage turbine Pumped hydro: pump water basin turbine Hydrogen storage system: electrolyser hydrogen storage fuel cell, turbine No 7 Energy generation from solar radiation and wind are highly fluctuating % of installed rated capacity % of installed rated capacity wind power PV % of installed rated capacity % of installed rated capacity wind power PV Figures: IAEW, Prof. Haubrich 1 hour 1 week Fluctuating power generation must be balanced either by flexible thermal or hydro power plants or by storage systems. No 8

5 Fluctuations of a large number of power generators level out on a minute basis hours 100 systems 1 system Spatial distributed photovoltaic systems balance the power output and makes fluctuating power generators more predictable. source: E. Wiemken, from WBGU report No 9... but not on an annual basis MW installed llie rte wind power Windkraftleistung Leistung Power X generated Windeinspeisung wind power average power X Figures: IAEW, Prof. Haubrich 0 1. Jan. Jan 1. Feb. Feb 1. Mrz. März Mar 1. Apr. Apr 1. Mai. May Mai 1. Jun. June Juni 1. Jul. Juli July 1. Aug. Aug 1. Sep. Sep 1. Okt. Okt Oct 1. Nov. Nov 1. Dez. Dec Dez No 10

6 Increasing renewable energy penetration requires increasing energy storage capacity primary energy [EJ/a] German Advisory Council on Global Change (WBGU) Source: WBGU (in German) geothermal energy other renewables Solar thermal power plant technologies (only heat) solar power (photovoltaics and solarthermal power plants) wind power biomass energy (modern) biomass energy (traditional) hydropower nuclear energy natural gas coal oil No 11 Wind energy is not a decentralised energy source source: IAEW, Prof. Haubrich In Germany, wind energy is localised mainly in the northern part near the coast lines. Future off-shore wind parks will result in up to several 10 GW of installed power in the North Sea. No 12

7 Gradients in the cumulative power generation from wind turbines are small 100 p 10 Variation must be compensated by thermal or hydro power plants and storage systems min 1h 0, % P WEA / P inst,wea source: ISET Kassel 2h 20 Probability of variations in the cumulative output of all wind generators in Germany within 15 min, 1 hour or 2 hours. No 13 Concentration of power generation results in overloads in transmission lines Problem can be solved by building new transmission lines installation of storage systems close to the power generators Storage systems allow for a more uniform load on the transmission lines. Storage systems supersede high investments in back-up thermal power plants source: IAEW, Prof. Haubrich High voltage transmission lines in Germany. Red segments are overloaded due to wind power generation in the northern part of Germany. No 14

8 Other possibilities to level power generation from solar energy... solar radiation Moscow Berlin Lisbon monthly average of solar radiation Cape Town Algiers Berlin source: V. Quaschning, from WBGU report time [MEZ] month This requires very large power transmission capacities throughout Europe or world-wide which are expensive and not available today. No 15 Energy storage vs. energy transport Transmission lines are the backbone of European power supply infrastructure. With infinite world-wide power transport capacities no storage systems would be necessary. Pro and cons for energy storage and power transmission lines: Storage systems efficiency depends on technology (40-80% round trip) very flexible in power and energy capacity reduce dependency on third party countries expensive essential in remote power supplies Transmission lines efficiency high (~ 5% losses/ 1000km) expensive, especially in sparsely populated areas requires world-wide co-operation, susceptible to international crises planning takes typically more than a decade transport capacity limited (~ 1 GW) No 16

9 Not all renewable energies are volatile by nature Wind power, photovoltaics and solar thermal power plants depend very much on the actual local weather conditions. Other renewables can be used perfectly for the control of grids, load levelling and reserve power: biomass (solid or gas) geothermal energy hydro power tidal energy Future energy systems will be always a mix from various technologies including storage systems. No 17 Autonomous power supply systems - remote houses pictures: Fraunhofer ISE No 18

10 Autonomous power supply systems - technical applications pictures: Fraunhofer ISE pictures: Fraunhofer ISE No 19 Autonomous power supply systems - design of PV-battery and PV-hybrid systems PV gen. charge controller PV-Gen. DC-loads MG motor gen. Battery = AC/DC direct current bus bar (DC) AC-loads = DC/AC alternating current bus bar (AC) Hybrid system: several generators supplementing each other (here: PV, wind and motor generator) WG wind gen. No 20

11 Autonomous power supply systems - rural electrification pictures: Fraunhofer ISE No 21 Rural electrification - solar home systems and village power systems (mini-grids) School, hospital, assembly hall school, hospital, assembly hall productive applications Central power supply station Distributed storage in each house (solar home systems) or in a central power supply station (mini-grid) No 22

12 Demand for heat storage Solar thermal power plants Solar thermal collector systems for residential houses or settlements Combined heat and power co-generation No 23 Solar thermal power plant with heat storage Source:Ciemat, Plata Forma Solar, Dr. Romero No 24

13 Concept for a seasonal heat storage in a settlement central heat station flat collectors gas gas burner cold water intake heat distribution collector network seasonal heat storage Source:Ruhr-Universität Bochum, Prof. Unger No 25 Combined heat and power co-generation heat storage Source:Buderus Source:DEFU, H. Weldingh No 26

14 Demand for heat storage Solar thermal power plants: to extend the operation time, to evenly supply power, and to increase the dispatchability Solar thermal collector systems for residential houses or settlements: to supply heat during nights, periods of bad weather conditions, or during winter months Combined heat and power co-generation: to decouple heat and power consumption in industrial applications or distributed power generation No 27 Heat vs. chemical vs. electrical energy storage Heat storage low exergy content, especially at low and medium temperatures fair energy density T = 100K: 116 kwh/m 3 phase change materials (latent heat) interesting ice / water: 93 kwh/m 3 water / vapour: 626 kwh/m 3 transport always requires mass transport Chemical storage higher exergy content higher energy density lithium-ion battery: 300 kwh/m 3 liquid hydrogen: 2,400 kwh/m 3 petrol: 10,000 kwh/m 3 Electricity 100% exergy very low energy density electrostatic field: ~10 kwh/m 3 magnetic field: ~10 kwh/m 3 transport without mass transport at speed of light, cables required No 28

15 Various materials for heat and technologies for electricity storage Heat storage materials water soil, concrete phase change materials (medium and high temperature) zeolithe stationary or mobile storage systems thermo-chemical metal hydride alanat No 29 Various materials for heat and technologies for electricity storage Heat storage materials water soil, concrete phase change materials (medium and high temperature) zeolithe stationary or mobile storage systems thermo-chemical metal hydride alanat Electricity storage technologies double layer capacitors flywheels supra-conducting coils conv. batteries (lead-acid, lithium, NiMH, NiCd,...) high temperature batteries (NaS, NaNiCl,...) redox-flow batteries zinc-bromine batteries compresses air pumped hydro hydrogen storage systems No 30

16 Technologies for Electrical Storage Systems Redox-Flow batteries Superconductive coils Hydrogen Various storage technologies are available or need further development - but all need improved integration into the grid or other applications Pumped hydro Flywheels Supercapacitors Supercapacitor Batteries - lead-acid, lithium, NaNiCl,... Compressed air No 31 Sizing of storage systems for different applications typical discharge time 1 year 1 month 1 week ½ day 1 hour 1 min 1 s 10 ms 8 10 W single home storage 10 - UPS installed power 1 kw 100 kw 10 MW GW 100 GW 1 - PV battery system 2 - solar home system 3 - PV hybrid 4 - village power supply 5 - load levelling LV 6 - load levelling MV 7 - load levelling HV 8 - stabilisation of wind t. kwh MWh GWh TWh installed storage capacity specific power [kw/kwh] No 32

17 Operating range of different storage technologies typical discharge time 1 year 1 month 1 week ½ day 1 hour 1 min 1 s 10 ms I III II IV 10 W VIII installed power 1 kw 100 kw 10 MW V 1 GW 100 GW I - capacitors, inductors II - supercaps, flywheels III - batteries IV - redox-flow batteries V - compressed air VI - pumped hydro VII - hydro storage VIII - hydrogen storage kwh MWh GWh TWh installed storage capacity VI VII specific power [kw/kwh] No 33 Matching among applications & storage technologies typical discharge time 1 year 1 month 1 week ½ day 1 hour 1 min 1 s 10 W installed power 1 kw 100 kw 10 MW 1 GW 100 GW specific power [kw/kwh] 10 ms kwh MWh GWh TWh installed storage capacity No 34

18 Conclusions I Storage technologies for a wide power and energy range are needed. Existing storage technologies can match the requirements - for heat and for electricity. However, several challenges must be faced: reduction of life cycle costs per energy throughput (increase of lifetime, decrease of investment costs) increase of energy density to decrease storage size increase of storage efficiency environmental compatibility of storage systems (recycling, integration into the landscape, poisonous materials) No 35 Conclusions II Energy systems with a high penetration of renewables need storage systems to avoid shut downs of power generators if generation exceeds consumption to minimise the need for additional transmission lines to avoid investments in power plants for peak power generation to make efficient use of combined heat and power plants to transfer heat energy from summer to winter No 36

19 The conference will show: Storing energy in present and future energy systems with a high degree of renewable energy penetration is an essential demand. Various technologies are available. Further research, development and demonstration in parallel with developing renewable energy technologies is necessary. Let us intensify our joint activities to make storage systems for our future energy systems as a cornerstone technology available! No 37 Enjoy the conference, make contacts and see the emerging and the mature technologies! Bild: Fraunhofer ISE Children in Indonesia regarding curious the battery storage systems of the power supply system of their village. No 38