Storing Sunshine Where the Sun Never Shines An Underground Storage Solution to Intermittent Solar Power
How do you store sunshine You convert it into hydrogen using an electrolyzer. Solar panel power Electrolysis Hydrogen Sunshine
Is hydrogen a good energy carrier? • Hydrogen has the highest mass energy content of all conventional energy sources. – 4.5 times that of coal – 3 times that of natural gas – 250 times that of batteries • 1 kg of hydrogen has energy content of 1 gallon of gasoline.
But hydrogen has one major drawback • While it has a high mass energy content, it is a very light gas with a very low volumetric energy content. – 30,000 BTU/liter for gasoline compared to 10 BTU/liter for hydrogen • Meaning that hydrogen requires large storage spaces with compression to provide an economical and practical storage system.
Which is the reason why underground storage is the perfect solution • Underground chambers (vertical wells) can be sized to accommodate wide range of storage capacities. • The surrounding ground provides a stress resistant boundary that is ideal for creating a pressure vessel.
So how are they made? • They are rotary drilled from the surface using conventional mine shaft drilling equipment. – Sizes from 4 – 20 ft in diameter – Depths up to 2,000 ft • They can be lined and capped on both ends to provide a fully-sealed underground chamber.
Unique approach to Water pressurization Electrolyzer Regulator • Electrolyzer produces regulated Pressurized Hydrogen pressurized hydrogen. (5000 psi) • Flood the chamber with water. Flooded • Regulate the water pressure to underground chamber (5000 water psi) match that of electrolyzer.
Simulation of the system
Flooded Underground Underground chamber is flooded with water from surface reservoir Flooded Chamber This flooding purges the chamber of air. Not to scale
Electric Grid 5000 psi Solar Farm PEM Electrolyzer Showing animation Whenever grid demand falls below the solar farm's capacity, the excess electricity is Underground diverted to a high-pressure PEM electrolyzer. Flooded Chamber The PEM electrolyzer produces pressurized hydrogen by water electrolysis. Not to scale
Water Tank Electric Grid Solar Farm PEM Electrolyzer This one-way valve controls pressure in This valve controls This valve controls electrolyzer so that hydrogen gas is released the flow of water the flow of water at a controlled constant pressure OUT OF INTO the chamber. the chamber. A series of pressure regulated, one-way control valves is used to control the water and hydrogen pressure. Flow allowed in Flow prevented this direction in this direction Not to scale
Water Tank Electric Grid Solar Farm PEM Electrolyzer Pressurized hydrogen (i.e. @ 5000 psi) from the electrolyzer enters the storage chamber. This valve is set at the same level as the electrolyzer valve and prevents the escape of water until the Water is nearly incompressible, so very little (5,000 psi) pressure is reached. gas will quickly compress the water in the chamber and the water fill pipe. Not to scale
Water Tank Electric Grid Solar Farm PEM Electrolyzer The pressurized hydrogen continues to flow As more pressurized gas into the storage chamber. accumulates in the chamber, a proportional amount of water will be released from the chamber through the pressure regulated control valve. Not to scale
Water Tank Electric Grid Solar Farm PEM Electrolyzer Hydrogen pressure The water and hydrogen gas are at constant pressure, regulated by the one-way control valves. Water pressure Not to scale Pressure
Water Tank Electric Grid Solar Farm PEM Electrolyzer The water and hydrogen gas are at constant pressure, regulated by the one-way control valves. This process continues throughout the filling of the chamber with hydrogen gas. Not to scale Pressure
Water Tank Electric Grid The stored hydrogen is removed from the chamber to regenerate power or supply a hydrogen fuel station. Not to scale
Water Tank Electric Grid As the stored hydrogen is removed from the chamber, the hydrogen pressure drops proportionally, but The hydrogen pressure is remains constant in the chamber. now equivalent to the hydrostatic pressure at the bottom of the chamber. Hydrogen pressure (psi) = 0.43 x chamber depth (ft) Not to scale Pressure
Water Tank Electric Grid PSI PSI Less than Water can now flow back Hydrogen pressure gradient now into the chamber controlled by hydrostatic water pressure Pressure (psi) = 0.43 x chamber depth (ft) Not to scale Pressure
Summarizing • Converting renewable energy into hydrogen through electrolysis. • Storing the hydrogen in man-made underground chambers. • Using water pressure to maintain stored hydrogen under pressure.
How much energy can be stored? Short answer – as much as you want.
Some examples … • Largest pumped hydro station in the world (capacity of 3,060 MW) with an 11 hour storage capacity of 24,000 MWh . • Two 16-ft-diameter, 2,000-ft-deep chambers could store more energy (105 pct or 25,228 MWh).
Some examples … • 5,000 kg - One 9.5-ft-diameter, 1,000-ft-deep chamber can fill up the fuel tanks of 1,000 hydrogen powered cars .
Some examples … • 230,769 MWh – Twelve , 20-ft- diameter, 2,000-ft-deep chambers could provide more than enough energy needed to fully power 1 million homes for a week.
Some examples … • One of the largest grid storage battery system in the United States at Beech Ridge, WV requires 18 batteries to provide 31.5 MW . • Our system can store 32 MWh in one small 5-ft-dia chamber only 80 ft deep .
Is it economical?
Cost Elements $3.89/kg $98.44/MWh $0.045/kWh Regeneration Energy Source Fuel cells Rechargeable Solar Wind Farm Conversion Storage Electrolysis Underground generated hydrogen Chambers $2.70/kg $0.10/kg $68.54/MWh $2.53/MWh
Cost Elements $3.89/kg $98.44/MWh $0.045/kWh Regeneration Energy Source Fuel cells Rechargeable Solar Wind Farm Conversion Storage Electrolysis Underground generated hydrogen Chambers $2.70/kg $0.10/kg $68.54/MWh $2.53/MWh
Concluding remarks
Comments on energy storage • The need for energy storage will grow exponentially as renewable energy supply increases and will be a necessity as it approaches baseload capabilities. • We believe our system provide a viable solution to this universal requirement.
The advantages of our system • It is easily scalable to provide capacities that support microgrid to commercial grid levels of stored energy. • A main advantage is that this system has no storage time limit (i.e. no cycle time concerns). • Using water provides two advantages: – Eliminates the need for any secondary mechanical compression. – Ensures safety by purging of air to ensure purity of hydrogen storage.
Other advantages of our system • The chambers can be placed at any convenient location. • Small surface footprint. • Long live (50 years). • No disposal costs.
The future outlook • Component technologies (electrolyzers and fuel cells) already exist commercially, but continue to improve in efficiency and drop in price. • Same is true for solar and wind power costs.
Storing Sunshine Where the Sun Never Shines We can do that!
No sun. No wind. No problem! US Patent 9,273,402 B2 Issued March 1, 2016 System and Method for the Manufacture, Storage and Transportation of Hydrogen and Oxygen Gas Joe Bower : joebower@solarwindstorage.com Visit our website at https://www.solarwindstorage.com Tom Barczak : tombarczak@solarwindstorage.com
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