1. Energy domain presentation: Energy Storage
Carrie Trant
Energy, Environment, Economy
Spring 2017

2. Overview: Grid scale energy storage
Balancing the grid without batteries:
increase power from conventional power stations when renewable output is low, disconnect renewable sources when power generated exceeds demand 1
Balancing the grid with batteries:
Increase efficiency by running power plants at maximum efficiency, with less ramp time, and storing/using stored energy as needed to make up the difference 2
Increase reliability: stable, abundant energy reserves that are available when needed 2
1. U.S. Energy Information Administration
2. Verma, et al. (2013) Energy Storage: A Review. International Journal of Innovative Technology and Exploring Engineering, 3(1): 63-69

3. Overview: Grid scale energy storage
1800: The first battery, “Volta’s Cell” 3
1929: The first large-scale energy storage facility in the US, Rocky River Pumped Storage Plant (Connecticut) 3
Currently, >98% total US storage capacity is pumped hydroelectric 1
US has 1,068 GW of energy generation capacity and 21.6 GW of energy in storage (June 2016) 3
2.5% of electric power in US has passed through a storage facility (10% of power in Europe and 15% in Japan) 3
1. U.S. Energy Information Administration
3. University of Michigan Center for Sustainable Systems: U.S. Grid Energy Storage Factsheet

4. Overview: Grid scale energy storage
4. International Energy Agency: Technology Roadmap, Energy Storage

5. Technology development: Power to Gas What is Power to Gas?
The conversion of electricity into a gas (e.g. hydrogen or methane) as a way to store energy chemically 5
Convert electricity that is generated when demand is low and production is high into hydrogen via electrolysis: splitting water into hydrogen and oxygen 1
Hydrogen is fuel, stored energy
Oxygen is a commodity itself, or can be released into atmosphere
1. U.S. Energy Information Administration
5. European Power to Gas

6. Sources and Resources: Renewable Energy
Renewables yield an increasing fraction of electricity generated, especially in Europe 5
Renewables are intermittent
The energy supply experiences more fluctuations in supply
Storage and/or transportation becomes more important
Can cause problems especially when there isn’t a mature grid to smooth out fluctuations
When production of electricity from renewables exceeds demand, it currently is lost. Example: Germany
5. European Power to Gas

7. Renewable energy is making energy storage technology even more important
5. European Power to Gas

8. Transformation (Production): Electrolyzers
Electrolysis:
water (H2O) + electricity  hydrogen (H2) + oxygen (O2)
6. Energy.gov, Office of Energy Efficiency and Renewable Energy

9. Transformation (Production): Electrolyzers
Prohibitively expensive way to produce hydrogen, compared to producing hydrogen from natural gas
2009 GE Research innovation: Richard Bourgeois’ group developed a prototype electrolyzer made with high-tech, moldable plastic instead of metal 7
A kilogram of hydrogen (~ energy of 1 gallon of gasoline): $3 instead of $6
But, electrolysis still hasn’t been implemented on a large scale (95% of hydrogen comes from natural gas)
7. Ward (2009) Cheap Hydrogen: GE's Low-Cost Electrolyzer. Popular Mechanics

10. Three ways to use H2 gas produced by P2G:
For burning as power generation or vehicle fuel (hydrogen by itself or blended with natural gas)
Use in fuel cells:
If use hydrogen gas as fuel, the chemical reaction is:
H2 + O2  electricity + H2O (only byproduct is water)
Combine hydrogen with carbon dioxide to make synthetic methane (CH4) as an alternative to natural gas
1. U.S. Energy Information Administration

11. 5. European Power to Gas

12. The Hydrogen Gas Economy
Energy density: hydrogen gas contains roughly 3x the energy of natural gas, per weight
Hydrogen is not a fuel – it is a way to store/transport energy; you must make it before you use it
Made by extracting hydrogen from fossil fuels (95%) or by running an electrolyzer with electricity and splitting hydrogen from water
Why fuel cells aren’t green yet: need to produce the hydrogen fuel from renewables to remove the dependence on fossil fuels
8. Wise (2006). The Truth About Hydrogen. Popular Mechanics

13. Technological Challenges: Hydrogen Storage
At room temperature, the low density of hydrogen means that an equivalent volume of hydrogen gas has <1/300 energy of gasoline
Room temperature and pressure: huge storage tanks
Liquefication (by chilling) needs a lot of energy: up to 1/3 energy of hydrogen, yields 1/4 energy of equivalent volume of gasoline
Compression to a very high pressure is dangerous: 10,000psi (680x atmospheric) yields 1/4 energy of equivalent volume of gasoline
Solid state (trap hydrogen in metal hydrides): very heavy
Dangers: hydrogen gas is easy to ignite (small spark), burns with colorless flame, gives off little IR heat but high UV radiation (easy to accidentally contact), burns very rapidly 10
8. Wise (2006). The Truth About Hydrogen. Popular Mechanics 10. Hydrogen Tools

14. Delivery and optimal uses: the gas pipeline
The natural gas infrastructure is well developed: could transport energy to remote, developing areas that may have gas infrastructure before electrical infrastructure 5
Connect offshore gas fields to shore, gas from wind would be accessible
In Honolulu, manufactured alternative to natural gas is currently delivered and used with similar to proposed hydrogen concentrations 9
5. European Power to Gas
9. Melaina, et al (2013). Blending Hydrogen into Natural Gas Pipeline Networks: A Review of Key Issues. National Renewable Energy Laboratory (NREL)

15. Delivery and optimal uses: the gas pipeline
Add hydrogen to natural gas pipelines at low concentrations, 5-15% hydrogen by volume 9
Store and deliver hydrogen without noticeably affecting the usage of natural gas from the pipeline: in terms of safety, how it burns, or integrity of the pipe infrastructure
Separate/purify hydrogen out of gas mix downstream, for use
Don’t need to build new dedicated hydrogen delivery infrastructure, but do need to build blending/extraction processes and additional pipeline integrity monitoring (hydrogen gas embrittles steel and other metals)
9. Melaina, et al (2013). Blending Hydrogen into Natural Gas Pipeline Networks: A Review of Key Issues. National Renewable Energy Laboratory (NREL)

16. Delivery and optimal uses: the gas pipeline
Case study: Europe 5
Well developed on- and off-shore natural gas infrastructure
Potentially will produce 100 GW of electricity from offshore wind by 2030 and 60 GW from photovoltaics by 2020
35 GW from photovoltaics in 2012
Germany in specific: could connect north (wind) to south (industrial, needs energy)
Industry and transportation could use renewable hydrogen! – break from carbon
5. European Power to Gas

17. Hydrogen gas compared to natural gas
Relative Vapor Density
Auto Ignition Temperature
Flammability Range
Minimum Ignition Energy
**at low concentrations of hydrogen in air, the energy required to initiate combustion is similar to that of other fuels**
10. Hydrogen Tools

18. Technological Challenges
Hydrogen gas embrittles steel and other metals; high diffusion through containment materials
Electrolysis is expensive, pretty significant efficiency losses 4
Electricity  hydrogen/methane  electricity is undesirable
22-50% efficiency of electrolysis 4
40-60% efficiency of fuel cells
Instead of using gas for electricity via gas turbines/fuel cells, use the gas for heating/industry feedstock 5
But, hydrogen is a portable way to store energy
4. International Energy Agency: Technology Roadmap, Energy Storage
5. European Power to Gas

19. 5. European Power to Gas

20. Social, ethical, legal, economic challenges
Dangers / perceived dangers of elevated hydrogen concentration in natural gas mix
Explosive limits of hydrogen in air: 18-60%
Flammable limits of hydrogen in air: 4-75%
Use water for electrolysis instead of drinking?
Legal / Economic:
Who manages the hydrogen supply? Hydrogen creation / injection into natural gas pipeline/ downstream purification/ etc.
How to split payments for pipeline upkeep between users?
Should there be state / federal tax incentives? Is the cost of circumventing greenhouse gases worth added cost/ infrastructure?

21. P2G Projects in Europe
5. European Power to Gas

22. P2G Project in the US! UC Irvine, December 2016
Funding from Southern California Gas Co.
Proton OnSite provided electrolyzer
hydrogen + natural gas is burned in the gas turbine power plant to generate electricity and heat
System is being monitored, research conducted as a proof of concept
11. University of California News

23. Thank you! Questions / Discussion
Goal is to use electricity that otherwise would be wasted. Added infrastructure, complexity but moves toward goal of zero greenhouse gases, renewable energy society

24. References
U.S. Energy Information Administration.
Verma, et al. (2013) Energy Storage: A Review. International Journal of Innovative Technology and Exploring Engineering, 3(1): 63-69
University of Michigan Center for Sustainable Systems: U.S. Grid Energy Storage Factsheet.
International Energy Agency: Technology Roadmap, Energy Storage.
European Power to Gas.
Energy.gov, Office of Energy Efficiency and Renewable Energy. production-electrolysis
Ward (2009) Cheap Hydrogen: GE's Low-Cost Electrolyzer. Popular Mechanics
Wise (2006) The Truth About Hydrogen. Popular Mechanics.
Melaina, et al (2013). Blending Hydrogen into Natural Gas Pipeline Networks: A Review of Key Issues. National Renewable Energy Laboratory (NREL)
Hydrogen Tools.
In a national first, UC Irvine injects renewable hydrogen into campus power supply. University of California News. campus-power-supply