Storing Sunshine Where the Sun Never Shines An Underground Storage - - PowerPoint PPT Presentation

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.

Sunshine Solar panel power Electrolysis Hydrogen

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 pressurization

Electrolyzer Pressurized Hydrogen (5000 psi) Flooded underground chamber (5000 water psi) Water Regulator

• Electrolyzer produces regulated

pressurized hydrogen.

• Flood the chamber with water.
• Regulate the water pressure to

match that of electrolyzer.

Simulation of the system

Not to scale

Underground chamber is flooded with water from surface reservoir This flooding purges the chamber of air.

Flooded Underground Flooded Chamber

Electric Grid Solar Farm PEM Electrolyzer

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Whenever grid demand falls below the solar farm's capacity, the excess electricity is diverted to a high-pressure PEM electrolyzer. The PEM electrolyzer produces pressurized hydrogen by water electrolysis.

Showing animation

5000 psi

Underground Flooded Chamber

Electric Grid Solar Farm PEM Electrolyzer

Not to scale

Water Tank

This one-way valve controls pressure in electrolyzer so that hydrogen gas is released at a controlled constant pressure Flow prevented in this direction Flow allowed in this direction A series of pressure regulated, one-way control valves is used to control the water and hydrogen pressure. This valve controls the flow of water OUT OF the chamber. This valve controls the flow of water INTO the chamber.

Electric Grid Solar Farm PEM Electrolyzer

Not to scale

Water Tank

This valve is set at the same level as the electrolyzer valve and prevents the escape of water until the (5,000 psi) pressure is reached. Pressurized hydrogen (i.e. @ 5000 psi) from the electrolyzer enters the storage chamber. Water is nearly incompressible, so very little gas will quickly compress the water in the chamber and the water fill pipe.

Electric Grid Solar Farm PEM Electrolyzer

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Water Tank

As more pressurized gas accumulates in the chamber, a proportional amount of water will be released from the chamber through the pressure regulated control valve. The pressurized hydrogen continues to flow into the storage chamber.

Electric Grid Solar Farm PEM Electrolyzer

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Water Tank

The water and hydrogen gas are at constant pressure, regulated by the

• ne-way control valves.

Pressure Water pressure Hydrogen pressure

Electric Grid Solar Farm PEM Electrolyzer

Not to scale

Water Tank

The water and hydrogen gas are at constant pressure, regulated by the

• ne-way control valves.

Pressure This process continues throughout the filling of the chamber with hydrogen gas.

Electric Grid

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Water Tank

The stored hydrogen is removed from the chamber to regenerate power or supply a hydrogen fuel station.

Electric Grid

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Water Tank

Pressure As the stored hydrogen is removed from the chamber, the hydrogen pressure drops proportionally, but remains constant in the chamber. The hydrogen pressure is now equivalent to the hydrostatic pressure at the bottom of the chamber. Hydrogen pressure (psi) = 0.43 x chamber depth (ft)

Electric Grid

Not to scale

Water Tank

Pressure Pressure (psi) = 0.43 x chamber depth (ft) Water can now flow back into the chamber Hydrogen pressure gradient now controlled by hydrostatic water pressure

Less than

PSI PSI

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

• f 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
• ne small 5-ft-dia chamber only

80 ft deep.

Is it economical?

Energy Source Regeneration Conversion Storage

Solar Wind Farm Electrolysis generated hydrogen Underground Chambers Fuel cells

Rechargeable

Cost Elements

$0.045/kWh $2.70/kg $68.54/MWh $0.10/kg $2.53/MWh $3.89/kg $98.44/MWh

Energy Source Regeneration Conversion Storage

Solar Wind Farm Electrolysis generated hydrogen Underground Chambers Fuel cells

Rechargeable

Cost Elements

$0.045/kWh $2.70/kg $68.54/MWh $0.10/kg $2.53/MWh $3.89/kg $98.44/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

Tom Barczak: tombarczak@solarwindstorage.com Joe Bower: joebower@solarwindstorage.com Visit our website at https://www.solarwindstorage.com