hydraulic rock storage introduction nov15 v2 1

Hydraulic Rock Storage (HRS) –

an Efficient System for

Large-Scale Energy Storage

An Introduction

November 2015

2© Heindl Energy GmbH, all rights reserved

1. Executive Summary

2. Why Energy Storage?

3. Storage Demand and Market

4. Technical Concept

Basic Physical Principle

Construction

Sealing

Location

5. Business Models and Competition

6. Current Status and Next Steps

7. About us

Contents


What’s the idea? Hydraulic Rock Storage (HRS) can be

used to store power, in the scale of multi-GWh, for 8 to 14

hours – potentially more efficiently than Pumped Hydro

Storage. We believe that HRS will be a game-changing

solution for the world´s energy supply, as photovoltaic

(PV) and wind power become the cheapest source of

electricity and the demand for power continues to increase

rapidly. HRS offers reliable 24-hour supply of solar and

wind power at steady, predictable costs. Additionally it

may be a contribution to resilience power systems.

How does it work? A piston of rock with diameter >100 m

is excavated in the ground from its natural surrounding

rock. In times of excess power, water is pumped under the

piston. When additional power is needed (e.g. at night or

in times of little wind), water is released from beneath the

piston, allowing it to fall, and used to drive turbines.

Generators are then used to produce electricity, which is

fed into the power grid.

Why so efficient? With each doubling of the diameter,

storage capacity increases at a rate that is roughly

proportional to the fourth power of the diameter (D4) while

construction costs only increase at a rate that is roughly

proportional to the second power of the diameter (D2).

This fact, a result of the applicable laws of physics and

geometry, is of groundbreaking significance for the cost

efficiency of storage. We estimate construction costs of

approx. 130 USD/kWh of storage capacity, with a physical

round-trip efficiency of over 80%.

What other key advantages does it offer? Unlike Pumped

Hydro Storage, HRS does not require any elevation

difference. (Suitable geological conditions are required,

but these can be found in many regions around the world.)

HRS plants can be built using proven technologies from

mining and tunnel construction, and can be expected to

have a service life of 60 years or more. And no chemicals

or other hazardous substances are used during

construction and operation, with water and rock being the

key materials required.

What’s the business case? The most likely business case

(without any subsidies) is a combination of PV or wind

production and HRS, ensuring reliable electricity at a

constant cost for a long time. This represents an attractive

model for a YieldCo based on long term PPAs in a range

of 110-120 USD/MWh.

What next? After developing this concept for the past four

years, we are currently preparing a pilot project to prove

the concept. We are also searching for a suitable site for a

first commercial application.

What can you do? Please contact us to discuss possible

applications you might be interested in for your business.

Executive Summary


Why Energy Storage?

A Vision of Clean and Reliable Power Supply


The wealth and prosperity of mankind have depended for

centuries on the availability and use of stored energy

sources such as coal, oil and uranium.

But times are changing rapidly. While fossil fuels are now

recognized to be damaging to our climate, new technologies

enable unlimited solar energy to be used to produce

electricity, with low environmental impact and at affordable

costs.

We believe that the demand for energy storage will continue

to grow strongly in the decades to come – due, in particular,

to the following global megatrends in electricity supply:

Solar energy will become the dominant source of power

supply for roughly 80% of the world’s population, with

wind power also featuring strongly in some regions.

Global energy consumption will continue to increase,

due to the ongoing electrification of daily life (IT, mobility,

cooling, desalination, etc.) in developed economies and

the industrialization of emerging economies.

How Energy Storage will Change the Global Energy System


Our Mission: 24 h Sustainable Energy Supply

Heindl Energy´s mission is to transform

the world’s energy storage landscape,

paving the way towards a sustainable,

clean global power supply.

Hydraulic Rock Storage (HRS), the

company’s brainchild, turns PV energy

into reliable 24-hour power in an

economically and technically feasible way.

By solving the energy storage challenge

in this way, we aim to support the

development of reliable power supply

systems that are 100% based on

production from renewable sources.


Storage Demand and Market


Solar power will become the cheapest source of electricity in many regions of the world, …

reaching costs of between 3.3 and 5.4 ct/kWh in 2025.

In North America, costs for large scale solar photovoltaics will reach 3.2 to 8.3 ct/kWh in 2025.

…The wide cost range due to significant geographical differences within the region.”

Source: Agora Energiewende: Current and Future Cost of Photovoltaics, 2015

PV will soon be the Most Cost-Efficient Source of

Power in the World.


80% of the World’s Population Lives in Regions

with enough Solar Irradiance to Satisfy Energy Needs.

Many emerging economies, which show the highest growth rate in electricity demand, are located in

regions where solar insolation exceeds 4 kWh/m2 per day.

To become the major power source, PV has to be connected with large scale daily storage for 8-14 h

to provide 24 h supply.


Global Growth of Fluctuating Renewable Power

Blue curve: trend, when average growth of PV and wind between 2011-2014 will continue, red curve: trend, when average growth since 1992 will continue. Installed power on log scale.Source: Prof. Heindl


Estimating future global storage demand:

To satisfy a 24-hour demand, a 1,000 MW PV

farm needs 300 MW of storage power with a

storage capacity of 2 GWh. Considering an

estimated future global PV production of 15,000

GW (should the world‘s electricity needs be

fully met by solar), this would require a global

storage capacity of 30,000 GWh.

Elon Musk estimates a global storage demand

of even 90,000 GWh in case of a complete

supply of all energy demand (incl. e-mobility) by

PV.

The Massachusetts Institute of Technology (MIT)

states, in a 2015 report on the future of solar

energy: The larger the quantity of added energy

storage capability, the higher the revenues

generated by PV plants and therefore the higher

the profitability of PV investments at any level.

Global Storage Demand

https://mitei.mit.edu/system/files/MIT Future of Solar Energy Study_compressed.pdf

© Heindl Energy GmbH, all rights reserved 12

An important business model for

HRS: Excess power from PV

plants is stored (purchased) during

the day and discharged (sold) at

night.

Utility companies and PV farm

operators must provide a reliable

power supply, at all times of day or

night, and thus need bulk storage.

Grid operators need bulk storage

to catch the ramping loads

occurring during sunrise and

sunset periods.

The Business Case of Bulk Energy Storage


Technical Concept


Technical Concept: Harnessing the Potential of

Gravity

How it works: A rock

piston, which has been

cut from the bedrock in

a selected location, is

lifted using water

pressure (by pumping

water into the space

beneath it), and when

electric power is

needed, pressurized

water is released and

routed to turbines.

150 m = 1 GWh

15

0 m

waterreservoir

Water forhydraulic

lifting

Large scalePV farms

Pump and turbine

piston of rock

rolling sealing

Access tunnel

Mass ~ r³

Height ~ r

Cost of construction ~ r²

Thus: Cost per kWh ~ r²/r4, or 1/r²

Energy storage capacity

E ~ 2 π g ρ * r4

EHRS = (2*ρR -3/2*ρW )* π*g*r4

(where ρR and ρW are densities

of rock and water respectively)

The economical benefit: Storage capacity, which is

roughly proportional to the piston’s mass (~ r³) and the

height lifted (~ r), increases with the fourth power of

the piston’s radius. Construction costs, however, only

increase with the square of the radius. This means that

construction costs increase much more slowly than

storage capacity as radius increases.

1

2

3

4


Construction

The rock piston is separated from the

surrounding bedrock, both underneath

and around its circumference, using rock

cutting machines.

All exposed surfaces are sealed with

geomembranes to protect against

environmental impacts and prevent loss

of water.

The gap between the piston and the

surrounding cylinder is sealed by a

flexible membrane.

Pumps, turbines, generators, etc. are

fitted as required.

Planning: 2 - 3 years

Construction: 3 - 4 years

Total: 5 - 7 years

Operation life:> 60 years


Excavation of the Piston

Using established mining and tunneling technology

To excavate the piston (i.e. to separate it from the surrounding bedrock), a spiral

tunnel (approx. 4 m high x 5 m wide), or alternatively a vertical shaft, providing

access to the piston‘s base level, is created by blasting. Working level tunnels are

created at various levels.

Source:

Access shaft

Working level tunnels

Base working level

Base tunnel

Spiral access tunnel(Alternatively: vertical shaft)

Connection tunnels

Connection tunnel


Excavation of Base of Piston I

1)

2)

3)

The excavation of the base

is a challenge which can be

mastered using mining

technology:

1) Drill holes and insert

explosives

2) Blast rock and remove

debris

3) Stabilize the base of the

piston with rock anchors


Excavation of Base of Piston II

Approved methods from underground mining

In order to ensure

stability, rock bolts will

probably have to be

installed in the roof

immediately after

excavation in each area.

The separation of the piston base from the

underlying rock is initially based on the well-

established “bord and pillar” method of

mining/extraction, with a series of parallel

tunnels (approx. 4m high and 5m wide, 5 m

apart) excavated as a first step. The

remaining 5m-wide walls of rock between the

tunnels initially support the weight of the

piston above. Reinforced concrete pillars, of

approx. 5m diameter, are then constructed at

regular intervals along each tunnel. With

these pillars in place, the remaining rock can

be excavated, at which point the weight of

the piston transfers to the new concrete

pillars. The concrete pillars, which are

securely anchored into the rock above and

below, are split at mid-height, with a stainless

steel sliding sheet inserted between the

upper and lower parts, enabling the piston to

move transversely and avoiding the build-up

of destructive constraint forces. The space

between the pillars will remain free, allowing

water to be pumped under the piston to lift it

and facilitating future access for maintenance

etc.


Assessment of Geophysical Stability

Effects of deformation of the rock cylinder and piston

Source:

Deformation of cylinder and piston at a diameter of 500 m (corresponding to a capacity of 124 GWh!).

Deformation of cylinder:Max 3.5 cm

Deformation of piston: Max 3.2 cm

3.5 cm deformation


The Sealing Challenge: The “Rolling Membrane”

Typical pressure at sealing membrane: 40 bar

Forces absorbed by steel cables

Flexibility accommodates piston movements

Self-centering

Production similar to conveyor belts

Full access for maintenance

PistonCylinder


Capacity [GWh] 0.2 1 2.1 3.2 8 124

Radius, Lift [m] 50 75 90 100 125 250

Diameter [m] 100 150 180 200 252 500

Volume of water[1000 m3]

392 1,325 2,290 3,141 6,284 49,087

Pressure [bar] 21 31 37 41 52 103

Size Variants at a Glance

HRS can be built with various diameters. At a diameter of

about 250 m, the storage capacity of a typical large pumped

hydro storage plant is already achieved.

These pressures are not very high; they are generally in the same range than in

pumped hydro stations.

The need for water is also far lower than in pumped hydro stations.


Location Requirements


Location Requirements

Geology:

• Compact homogeneous rock with little

tendency to fracture. The more compact

the rock, the lower the cost of

construction.

• Young’s modulus (E) of at least 10,000

MPa

• No mountain or elevation difference

required!

Hydrology:

• Proximity to a water supply and drainage,

but large-scale upper and lower basins

(as required by pumped hydro storage)

not required. A single, smaller reservoir is

sufficient.


Advantages:

• Good rock quality generally available

at bottom of quarry

• Geological conditions largely known

• Already used for surface mining

• Largely out of sight since below the

surrounding ground level

• Water often present in old mines

• Good infrastructure, grid connection

Possible Locations I

Quarries

Illustrative, not a real project


Large PV power plants

Possible Locations II


Hydraulic Rock Storage: The case of Las Vegas

1 GW of PV (300 MW finished, 700 in planning), with an 8 GWh HRS plant

HRS plant(real scale!)

Large PV power plants

Possible Locations III


HRS Business Models and Competition


Costs of Constructing the Piston and Cylinder

0 €/kWh

60 €/kWh

120 €/kWh

180 €/kWh

240 €/kWh

,,0

100,000,000

200,000,000

300,000,000

400,000,000

50 m 75 m 100 m 125 m Radius

Cost in mn USDCost per unit of

storage capacity

270 USD/kWh

66 USD/kWh

0 USD/kWh

132 USD/kWh

198 USD/kWh

440

330

220

110

0

8 GWh1 GWh Capacity

Source:

(excluding turbines, pumps, generators, grid connection etc.)

We show the costs of constructing the piston and cylinder separately from the total costs (following slide) due to make the figures more comparable to other technologies. Many number used in the debate about costs of storage do not include total costs.


Total Costs of Construction

200MWh ; 595$/kWh

1.000MWh; 278$/kWh

2.100MWh; 203$/kWh

3.200MWh; 172$/kWh

8.000MWh; 124$/kWh

16.000MWh; 100$/kWh

$/kWh

100 $/kWh

200 $/kWh

300 $/kWh

400 $/kWh

500 $/kWh

600 $/kWh

700 $/kWh

100 MWh 1.000 MWh 10.000 MWh 100.000 MWh

US

D/k

Wh s

tora

ge c

apacity

MWh storage capacity (log)

Larger radius leads to a very cost efficient storage falling below USD 100 (EUR 91) / kWh capacity when 16 GWh (= 160 m radius) are equipped with 1’000 MW turbines (= 16 hours).


HRS Business Models

Each of these models can be combined and varied with respect to:

• the number of cycles per year

• the design and capacity of the required pump and turbine equipment

HRS strives for profitability without reliance on subsidies.

The PPA model is the most promising one at present, being likely to be

profitable already in sunny regions.

PPA (Power Purchase

Agreement):

Combine PV or wind

energy production with

HRS, delivering 24-hour

electricity at a fixed price

(120-140 USD/MWh) for

20 years or more. Could

ideally be run as a

YieldCo.

Arbitrage model:

Charge storage at low

prices, sell energy at

higher prices.

Providing system

services:

As a source of flexibility

and security of supply.

Ancillary services, black-

out prevention etc.

Energy-intensive

industries:

Reducing peak loads.


Preferred Markets and Target Regions for HRS

1. For use as daily storage in

regions with high PV energy

production. PPA for “production plus

storage” at a reliable long-term

price.

2. In regions with particularly high

demand for supply security and

ancillary services, and where

• Electricity demand is growing

significantly

• Steep ramping occurs

• PV and wind energy generation

is expanding

• Security of supply is considered

to have particular value for the

national/regional economy

• Pumped hydro storage is not

possible due to the lack of

height difference in the local

terrain

The so-called “duck curve”: The increasing ability of PV in the years to come to directly meet daytime energy needs will result in increasingly steep ramping towards evening. This causes demand for stored energy.

Source:https://energyathaas.wordpress.com/2013/07/29/whats-the-point-of-an-

electricity-storage-mandate/

https://energyathaas.wordpress.com/2013/07/29/whats-the-point-of-an-electricity-storage-mandate/


Current Status and Next Steps

About us


Current Status and Next Steps

What has been completed:

• Patents granted for the system

• Patents applied for sealing

• Feasibility studies with respect to geology, geomechanics and construction

• Development of sealing concepts

• Cost estimates

• Financial model incl. revenue scenarios

• A suitable site for a pilot project has been found. Design, preplanning and calculation

has been completed.

• Technology Partners for sealing and engineering.

What is ongoing:

• Application for approval for construction of the pilot project

• Search for investors and public funding to realize the pilot project

• Presentation of the concept to the global energy industry and science community

• Search for sites for commercial application of HRS

What are the next steps (2016 and beyond):

• Commencement of planning for pilot project

• Estimated time for approval and planning: 1 year

• Estimated time of construction: 2-3 years

• First commercial applications commissioned in 2024


Heindl Energy‘s purpose is to develop and,

together with its partners and investors,

realize the Hydraulic Rock Storage as a

beneficial and profitable means of energy

storage. The company is currently planning a

pilot project to prove the concept‘s viability,

and already holds all required patents.

Heindl Energy was founded 2013 and is

based in Stuttgart, Germany.

The company’s founder and main

shareholder is Professor Eduard Heindl, and

the main investor is HTG Ventures AG,

Switzerland.

Further information:

www.heindl-energy.com

About us

Heindl Energy GmbH, Stuttgart, Germany

Prof. Dr. Eduard Heindl,Managing Partner

Robert Werner,Executive Director

Prof. Dr. Simone Walker-Hertkorn,Head of Geology

Dr. Karin Widmayer,Project Management

Management Team:

http://www.heindl-energy.com/


Profitability:

Economy: Construction cost per unit of storage capacity decreases

rapidly with increasing radius (proportional to 1/r²)

Particularly promising business cases in combination with PV (without

subsidies)

Efficiency: High, at 80% (comparable with pumped hydro storage)

No elevation difference needed (unlike pumped hydro storage)

Construction technologies have long been used (e.g. in mining and

tunneling industries)

Low running costs

Sustainability:

low raw material requirement, “just rock and water”

Low land footprint

Requires less water than pumped hydro storage (~ 1/4)

Long service life of over 60 years

Reliability:

Security of supply: buffers fluctuating power on an Gigawatthour-scale

System services: ancillary services, black start capability, rotating masses

Easy operation

Advantages of Hydraulic Rock Storage

Thank you for your attention.

Heindl Energy GmbH

Meitnerstrasse 9

70563 Stuttgart

Germany

Tel.: +49 711 6569689-0

[email protected]

www.heindl-energy.com