Energy Storage Alternatives for Household and Utility-scale - - PowerPoint PPT Presentation

Energy Storage

Alternatives for Household and Utility-scale Applications

Marc Secanell

Energy Systems Design Laboratory, http://www.esdlab.mece.ualberta.ca Department of Mechanical Engineering, University of Alberta, Edmonton, Canada Solar Energy Society February 25, 2015

Overview

• About the presenter
• Introduction

 Why do we need energy storage?  How much energy storage do we need?  Choosing among options

• Small scale/Residential energy storage

 Electrochemical batteries  Flywheels

• Large scale/Grid scale energy storage

 Pumped-hydro  Synthetic fuels, e.g., solar hydrogen

• Conclusions

2

About the presenter

• Experience

2013-Present, Associate Professor, University of Alberta, Department of Mechanical Engineering

• Teaching: Energy conversion, Thermo-fluid systems design,

Electrochemical systems

• Research: Director of Energy systems design laboratory

2009-2013, Assistant Professor, University of Alberta, Department

• f Mechanical Engineering

2008-2009, Assistant Research Officer, National Research Council, Institute for Fuel Cell Innovation

• Education

Ph.D. Mechanical Engineering, University of Victoria, Canada, 2008 M.A.Sc. Mechanical Engineering, University of Victoria, Canada, 2004 B.Eng., Universitat Politècnica de Catalunya, Barcelona, 2002

3

Energy systems design laboratory: Overview

• Mandate: "To design energy systems

that can meet society’s needs while minimizing their cost, environmental and socio-political impact."

• 10 researchers
• 1 Post-doctoral fellow
• 3 Ph.D. students
• 5 M.Sc. students
• 1 undergraduate students
• Open for collaboration with local

industry

• Website:

http://www.esdlab.mece.ualberta.ca/

4

Energy systems design laboratory: Expertise

Computational Analysis of Energy Systems

• Developing energy system

models and simulation software, e.g., openFCST

• Clean hydrogen

production processes Computational Design and Optimization of Energy Systems

• Polymer electrolyte fuel cell

design

• Flywheel design

Experimental Testing of Energy Systems

• Fuel cell fabrication and

testing

• Hydrogen electrolyzer

fabrication and testing

• Flywheel fabrication an testing

5

Overview

• About the presenter
• Introduction

 Why do we need energy storage?  How much energy storage do we need?  Choosing among options

• Small scale/Residential energy storage

 Electrochemical batteries  Flywheels

• Large scale/Grid scale energy storage

 Pumped-hydro  Synthetic fuels, e.g., solar hydrogen

• Conclusions

6

Why do we need energy storage?

• Our current energy infrastructure can be simplified to:

7

Why do we need energy storage?

• Energy supply:

8

***Includes geothermal, solar, wind, heat, etc. Source: International Energy Agency, Key World Energy 2014.

Why do we need energy storage?

• Our energy storage are our coal, oil and natural gas reserves

 Heating: Natural gas pipeline  Transportation: Gas stations, refineries  Electricity: Electrical grid

• The electrical grid is the largest just-in-time supply system in the

world

 Electricity demand matched by turning on/shutting down power plants

• Power plants with largest inertia, e.g., nuclear and coal, are not usually

shut down

 Current storage in U.S. can provide 2.3% of the grid power capacity, i.e. 23.6 GW

• Energy vs. power

 Energy = Joules or kWh = “how much water is in the bathtub”  Power = Energy / Time = MW = “how fast is the water draining” 9

Why do we need energy storage?

• Increased use of renewable

energy in households

 Solar PV to produce electricity  Solar thermal for DHW

• Global goal to increase

renewable energy production worldwide

 Reduce GHG emissions  Distributed and large-scale solar PV, wind farms, …

10

Source: Mill Creek NetZero greenedmonton.ca

Source: International Energy Agency, Key World Energy 2014.

Why do we need energy storage?

• Renewable energy resources are intermittent

 They cannot be switched on/off on demand

• Reduce our current ability to match supply and demand

Resource is intermittent and hard to predict High energy demand hours/months do not match with high energy production hours

• Solar: Highest production hours from solar would be 10-16h but

highest demand hours would be 18-22h 11

Source: Fraunhofer Institute for Solar energy systems (ISE) Electricity production from solar and wind in Germany in 2011

Why do we need energy storage?

• Wind production in Alberta, first week of January 2010

 Data from Alberta Electric System Operator

• Variability leads to curtailment

At very high production times, AESO cannot accept all wind power due to oversupply and transmission limitations (2-10% not used)

12

100 200 300 400 500 600 2000 4000 6000 8000 10000 12000

Power produced (MW) Time in minutes

Wind power production from Jan 01 to 07, 2010 (MW)

Energy storage options: All-electric

• Option 1: All-electric energy storage/transportation

13

Energy storage options: All-at-once

• Option 2: Electric and fuel energy storage system

14

e-

Choosing among options

• Questions you should ask (yourself) when selecting an energy

storage option

 How much energy do we want to store?

• Specific energy and energy density (in kWh/kg or kWh/m3)
• Discharge depth limit

 How much power do you need the system to provide?

• Specific power and power density (in W/kg and W/m3)

 How much of the energy stored do you expect to recover, and after how long?

• Turnover efficiency
• Losses during charge, no-load (self-discharge) and discharge

 How long do you want your system to last?

• Durability (cycling capacity)

 What type of energy do we want to store? What do we want to use the stored energy for?  How much are you willing to pay up-front (capital cost)? Overall? 15

How much do we want to store?

• Household storage:

 In 2011, the average Canadian household consumed 105 GJ/yr

• ~ 40% (actually 38%) electricity
• 45% natural gas
• Rest wood, oil and propane

 NG used for heating  Electricity used for heating (in some provinces), appliances, etc.  If we want to store only necessary electrical power we would need: 32 kWh/day

16

Source: Statistics Canada, Households and the Environment: Energy Use, 2011

How much do we want to store?

• Grid level storage

 Wind power in Alberta  Total capacity: 1,434 MW (9% total capacity)  Provided 5.1% of the energy in Alberta  In Jan 01-07, 2010, average power 126.06 MW, peak 500 MW

• Curtailment of wind power generation due to oversupply and

transmission constraints

17

100 200 300 400 500 600 2000 4000 6000 8000 10000 12000

Power produced (MW) Time in minutes

Wind power production from Jan 01 to 07, 2010 (MW) ~20 TJ = 5,555,556 kWh = 5.56 GWh

How much do we want to store?

• If I produce electricity using renewable energy, then I can be

“energy independent” and “zero-emissions”

• Not so quickly…

What about transportation, heating and industrial applications?

18

Source: Statistics Canada, Households and the Environment: Energy Use, 2011

Choosing among options

• The answer to these questions leads to different energy

storage options

19

Source: Fraunhofer institute

Choosing among options

• Cost is different per unit energy and per unit power

20

Source: H. Ibrahim, Renewable and Sustainable Energy Reviews, 12:1221-1250, 2008

Choosing among options

• Capital cost are not the full story

 Cost also depends on the durability of your technology

21

Source: H. Ibrahim, Renewable and Sustainable Energy Reviews, 12:1221-1250, 2008

Energy storage options

• Electricity must be stored in some other energy form, e.g.,

chemical, kinetic, potential and thermal

• In this presentation we will focus on one of the most mature

and one of the most “risky” for residential and grid-scale storage

 Flywheel energy storage (residential scale)  Chemical energy storage (residential and grid-scale)

• Batteries
• Hydrogen

 Pumped hydro (grid scale)

• Many other available

 Compressed air energy storage (grid scale)  Thermal energy storage (TES) (grid and residential scale)  Ultra-capacitors (residential scale)

22

Overview

• About the presenter
• Introduction

 Why do we need energy storage?  How much energy storage do we need?  Choosing among options

• Small scale/Residential energy storage

 Electrochemical batteries  Flywheels

• Large scale/Grid scale energy storage

 Pumped-hydro  Synthetic fuels, e.g., solar hydrogen

• Conclusions

23

Electrochemical batteries: How they work

• Energy is stored in the form of chemicals inside the battery

 During discharging the positive electrode is reduced and the negative electrode oxidized During charging the positive electrode is oxidized and the negative electrode is reduced Example: Lead-acid battery

24

𝑂𝑓𝑕𝑏𝑢𝑗𝑤𝑓 𝑓𝑚𝑓𝑑𝑢𝑠𝑝𝑒𝑓 (𝑒𝑗𝑡𝑑ℎ𝑏𝑠𝑕𝑓): 𝑄𝑐 𝑡 + 𝑇𝑃4

2− → 𝑄𝑐𝑇𝑃4(𝑡) + 2𝑓−

𝑄𝑝𝑡𝑗𝑢𝑤𝑓 𝑓𝑚𝑓𝑑𝑢𝑠𝑝𝑒𝑓 (𝑒𝑗𝑡𝑑ℎ𝑏𝑠𝑕𝑓): 𝑄𝑐𝑃2 (𝑡) + 4𝐼+ + 𝑇𝑃4

2− + 2𝑓− → 𝑄𝑐𝑇𝑃4(𝑡) + 2𝐼2𝑃

Source: http://chemwiki.ucdavis.edu

Electrochemical batteries: Energy storage capacity

• Different types of batteries depending on

 Positive and negative electrode materials  Electrolyte: Medium transporting ions, e.g., H+, SO4

2-

 Most common rechargeable (secondary) batteries:

25

Source: Linden and Reddy, Linden’s Handbook of Batteries, 4th ed., 2011

Electrochemical batteries: Energy storage capacity

• Specific energy numbers based on optimal discharge conditions
• Performance might be significantly different due to

 type of discharge

• Rate of discharge
• Continuous or intermittent

 temperature of the battery during discharge  service life (number of cycles) 26

Source: Linden and Reddy, Linden’s Handbook of Batteries, 4th ed., 2011

Electrochemical batteries: Ratings

• Decision matrix based on all factors:

27

Source: Linden and Reddy, Linden’s Handbook of Batteries, 4th ed., 2011

Electrochemical batteries: Advantages and disadvantages

• Advantages and disadvantages change with type of battery
• Advantages

 Moderate capital cost per unit energy (specially for lead-acid)  Easy to extend due to modular installation

• Disadvantages

 Poor cost per cycle (specially for lead-acid)  Low energy density (only applicable to small scale applications)  Safety as some use dangerous materials and some can ignite (e.g., Li-ion)

• For kWh scale,

 Lead-acid batteries remain the best compromise between cost and performance  Lithium-ion has better performance and durability but is more expensive  Austin Utilities Energy Storage Pilot

• Four lead-acid 9.2 kW/23.6 kWh Silent Power storage units installed in

municipal buildings for peak demand management.

28

Flywheels: How they work

• Electrical energy is stored in the form of kinetic energy

in a high speed rotor

• Rotor types:

Low speed rotor: Steel rotor High speed rotor: High-strength composite materials

29

Source: M. Krack, M. Secanell and P. Mertiny, Rotor Design for High-Speed Energy Storage Flywheel Systems, InTech, 2012

Flywheels: How they work

• Decoupling of power and energy storage

 Power rating controlled by motor/generator  Energy storage controlled by rotor size and speed

• Energy storage is given by:

𝐹 =

1 2 𝐽𝑨𝑨𝜕2 [J]

where ω is the rotational speed in rad/s and Izz is the moment of inertia, i.e.

𝐽𝑨𝑨 =

1 2 𝜌𝜍ℎ(𝑠 𝑝4 − 𝑠 𝑗4)

where ρ is the density of the material, and h and r are the rotor height and radius

30

More info see: M. Krack, M. Secanell and P. Mertiny, Rotor Design for High-Speed Energy Storage Flywheel Systems, InTech, 2012

Flywheels: Energy storage capacity

• Flywheel speed, and rotor size and

weight control the maximum energy storage

• A flywheel of 45 cm radius and 20 cm

height rotating at 30,000 rpm stores 35.2 kWh

 This is more than the 32 kWh/day needed to power your house for one day

31

Source: M. Krack, M. Secanell and P. Mertiny, RotorDesign for High-SpeedEnergy StorageFlywheel Systems, InTech, 2012

Flywheels: Advantages and disadvantages

• Advantages:

 Cheap, non-toxic raw materials  Minimal cycling degradation  Energy and power requirements are decoupled  High volumetric power density

• 310 Wh/kg

 Low capital cost per cycle

• Disadvantages:

 Rapid self-discharge. It can be minimized by:

• Operating under vacuum
• Using magnetic bearings
• Physically decoupling the motor during
• peration

 Safety

• Robust enclosure necessary

 High capital cost per unit energy

32

Flywheels: Commercial examples

• Temporal Power, Canada

In the grid: Hydro One uses flywheels for frequency regulation

• n a feeder that is connected to

two 10-megawatt wind farms in southwest Ontario

• VYCON Tech.

REGEN kinetic energy storage system at the Los Angeles County Metropolitan Transportation Authority (Metro) saves nearly 20% in energy consumption

33

Source: http://temporalpower.com/ Source: http://www.vyconenergy.com

Flywheel prototype (UAlberta)

• Proof of concept

(University of Alberta)

Dual rotor with 5cm height and 10-17cm and 17-20cm radii Magnetic and low-friction ceramic bearings Operated at 0.13 bar pressure A 5.5 kW motor type Kontronik PYRO 850-50 Up to 12,000 rpm thus far

34

Collaboration with Dr. Pierre Mertiny

Flywheel prototype (UAlberta)

• Energy storage thus far 31 Wh

Theoretical 138 Wh (at 30,000 rpm)

35

Overview

• About the presenter
• Introduction

 Why do we need energy storage?  How much energy storage do we need?  Choosing among options

• Small scale/Residential energy storage

 Electrochemical batteries  Flywheels

• Large scale/Grid scale energy storage

 Pumped-hydro  Synthetic fuels, e.g., solar hydrogen

• Conclusions

36

Pumped-hydro storage

• During periods of low electricity demand, water is pumped

from a low to a high reservoir. When demand increases, the flow is reversed.

• In US, 95% of current energy storage provided by pumped

hydro

37

Racoon Mountain Pumped-Storage Plant

Source: http://www.tva.gov/power/pumpstorart.htm

Estany Gento – Sallente water pumping station (Catalonia) Capacity: 6.5e6 m3

Pumped-hydro storage: How it works

• Parameters influencing the plant are:

Reservoir height Flow rate (reservoir available volume) Pump/turbine/generator efficiencies

• Overall 70-80% possible
• Mathematically,

where V is the available volume, Q p and Q T are the flowrates, in m3/s and ηp, η𝑛, η𝑈 and ηg are the pump, motor, turbine and generator efficiencies 38

𝐹𝑈 = 𝜃𝑈𝜃𝑕𝜍𝑕𝐼𝑈𝑊 𝑄𝑈 = 𝜃𝑈𝜃𝑕𝜍𝑕𝐼𝑈𝑅 𝑈 𝐹𝑞 = 𝜃𝑞𝜃𝑛𝜍𝑕𝐼𝑞𝑊 𝑄

𝑞 = 𝜃𝑞𝜃𝑛𝜍𝑕𝐼𝑞𝑅 𝑞

Pumped-hydro storage: Example

• Estany Gento – Sallente (Catalonia)

 Capacity lower reservoir 6.5e6 m3  Change in height: 370 m  Storage capacity (assuming η=80%)

• 18.86 TJ (2-5 TJ more likely) vs. 20 TJ

for Alberta wind energy

 Assuming 80% efficiency, a height of 100m and a depth of 50m, the reservoir would need to cover a square

• f 1 km by 1 km

 Grid scale storage can be accomplished but requires large storage facilities

39

Estany Gento – Sallente water pumping station (Catalonia)

Pumped-hydro storage: Advantages and disadvantages

• Advantages

 Large energy storage and power potential

• 1 TJ = 277,777 kWh

 High overall efficiency (70-80%)  Small self-discharge (due to evaporation)  Negligible cycling degradation Lowest capital cost per unit power and low capital cost per unit energy (but a lot of energy…)

• Disadvantages

 Requires a mountainous topology  Requires large land area (km2 scale)

40

Solar Hydrogen: Overview

• Store energy as compressed hydrogen in underground reservoir
• Electrochemical or photo-electrochemical converter used to split

water into hydrogen and oxygen and stored

• Hydrogen converted to electriciy when required using a fuel cell

41

Source: Shell Corp., HyUnder Project Launch, November 2012

Solar Hydrogen Production: Using electricity

• Electricity is used to split water in the anode producing

protons and oxygen

• At the cathode protons are combined to produce hydrogen
• Hydrogen can be produced at high pressure for storage or

injection into the natural gas pipeline

42

Source: www.azocleantech.com

𝐵𝑜𝑝𝑒𝑓: 2𝐼2𝑃 → 𝑃2 + 4𝐼+ + 4𝑓− 𝐷𝑏𝑢ℎ𝑝𝑒𝑓: 4𝐼+ + 4𝑓− → 2𝐼2

Solar Hydrogen Production: Using electricity

• Goal: 80-85% (HHV) efficiencies with hydrogen at

pressures of 300bar.

• Examples (Study performed in 2004):

43

Manufacture Model System Energy [kWh/kg] Hydrogen Prod. [kg/hr] Conversion efficiency Energy efficiency Hydrogen pressure [atm] Stuart (alkaline)

53.4 5.40 80 73 25

Teledyne (alkaline)

62.3 3.77 80 63 4-8

Proton (PEM)

70.1 0.90 95 56 14

Norsk (alkaline)

53.5 43.59 80 73 30

Avalance (alkaline)

60.5 0.45 89 64 Up to 680

Solar Hydrogen Production: Direct conversion

• A photo-voltaic cell in immersed in water
• The PV cell provides the potential difference necessary to

drive the water oxidation reaction

• 12.4% solar-to-fuel efficiency demonstrated in 1998
• 10% solar-to-fuel efficiency using non-precious materials

demonstrated in 2014.

44

Source: K. Maeda, J. Photochemistry and Photobiology C: Photochemistry Reviews. 12, 237 (2011). 𝐵𝑜𝑝𝑒𝑓: 2𝐼2𝑃 → 𝑃2 + 4𝐼+ + 4𝑓− 𝐷𝑏𝑢ℎ𝑝𝑒𝑓: 4𝐼+ + 4𝑓− → 2𝐼2

Hydrogen energy content

• Specific energy and energy density

 0.54 MJ/kg (Li-ion) vs. 119.95 MJ/kg  1.44 MJ/L (Li-ion) vs. 0.01 MJ/L (1 atm) or 1 MJ/L (100 bar)

45

Hydrogen (H2) Gasoline (C8H18) Hydrogen to carbon ratio 1:0 2.25:1 Freezing point [ºC]

• 259.2
• 56.8

Boiling point [ºC]

• 252.77

125.7 Net enthalpy of combustion of @ NTP* [MJ/kg]

• 119.95

(LHV)

• 48.27

(LHV) Heat of vaporization [kJ/kg] 445.69 368.1 Density @ NTP [kg/m3] 0.084

• Liquid density [kg/m3]

77 702

• Large volume reservoir

and compression required

Compression 5-15% loss

Hydrogen storage underground: Examples

• Previous underground storage of

hydrogen and synthetic gas (H2-CO) mixes

 In England, at Teesside, Yorkshire, the British company ICI has stored 1 million Nm3 of nearly pure hydrogen (95% of H2 and 3-4% of CO2) in three salt caverns at about 400 m in depth for a number of years.  In France, the gas company Gaz de France has stored a synthetic "town gas" 50-60% hydrogen in an aquifer of 330 million Nm3 capacity between 1956 and 1974 . No gas losses or safety problems have been reported  In Germany, at Kiel, a 62% H2 town gas was stored in a salt cavern of 32000 m3 at 80-100 bar  In 2007, Praxair opened an underground cavern hydrogen storage facility in Texas

46

Sources: http://www.ika.rwth-aachen.de/r2h/index.php/Large_Hydrogen_Underground_Storage http://www.praxair.com/news/2007/praxair-commercializes-industrys-only-hydrogen-storage

Solar hydrogen utilization

• Consumed as a fuel for heat, chemical products or

electricity

• For electricity, in a fuel cell for higher efficiency: 40-60%

47

H2 O2

  

 e H H 2 2

2

฀ O2  4H   4e  2H2O

H2O H+ e

• e

• Advantages

 Large energy storage and power production potential  Negligible self-discharge  Hydrogen can be used also for

• ther application such as heating

and transportation

• Disadvantages

 Cost (85% is the cost of the electrolyzer unit)  Low overall efficiency

• If heat: 60%
• If electricity: 25-40%

Hydrogen storage: Advantages and disadvantages

Source: www.azocleantech.com

Source http://www.isecorp.com/gallery/albums/BC-Transit-Fuel- Cell-Bus/BCTransit_fuel_cell_bus.jpg

Hydrogen storage: A possible road to mobile energy storage

• In Canada, 30% of energy consumption

is due to the transportation sector

 Dependant exclusively on fossil fuels

• Hydrogen fuel cells are one of the main

alternatives for zero-emission vehicles

• Chevy Volt

 16 kWh energy storage (1/2 day)  Li-ion battery  Cost: $38,500

• Toyota Mirai

 60 kWh energy storage (2 days)  5kg of H2 in 700 bar compressed tank  Cost: $57,500

• Grid storage: To store 20 TJ you need

347,222 Chevy Volts

49

Source: http://insideevs.com

Source: http://www.greencarreports.com

Hydrogen storage at UAlberta

• Fabricating and testing

 Fuel cells  Electrolyzers

• Cost main drawback of the

technology

• Cost due to expensive

catalyst materials

• Research on

 Low catalyst loading electrodes  Mathematical modelling and design of fuel cells and electrolyzers  Improving fuel cells for low temperature operation

50

1.7 μm

Conclusions

• Currently, fossil fuels are our energy storage
• To increase the use of renewable energy sources, more

energy storage is needed

 It is estimated that without storage only 20% of energy can come from renewable sources

• Many energy storage options available

 Residential scale

• 32 kWh/day required
• Available options: Batteries, flow batteries and flywheels

 Grid scale

• Several GWh required (20 TJ)
• Available options: Pumped-hydro, compressed air, flow batteries and

hydrogen 51

Acknowledgement

52

Thank You