DNV GL ©2019 SAFER, SMARTER, GREENERDNV GL ©2019

Reuse and second life: Conditions for a viable business model

1

Koen Broess

DNV GL ©20192

Ideal system characteristics for storage

High Penetration of

Renewables

Weak electrical networks

and networks requiring

upgrades

System Flexibility required

to align supply and

demand

Off-Grid Systems

High usage of peaking

diesel generators

Driving efficiency in renewables and gas

peaking plants

Policy and Regulation

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Potential revenue streams and energy cost savingsfrom stacked applications

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DNO Constraint Management

Services

Revenue via availability payments

(Arbitrage, peak shifting)

Revenue via energy payments

Demand Charge Reductions,

Imbalance Risk Hedging, Back up

power, Outage mitigation

Offtaker

Revenue via energy payments

PPA

Multiple revenuestreams

Ancillary Services

(Frequency Response, Reserve Services)

Trade on short time scale spot

markets

PPA?Service

Agreements?Delivery

Auctions?

Ramp Rate Control

Time Shifting

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PPA pricing structures

PPA-Price

€/MWh

Profile-

factor

Imbalance-

factor

Spot price

€/MWh

Compensation for price

difference between

average market price

and Asset capture price

Compensation for

Imbalance costs

Depending on the exact subsidy scheme (wind & solar), pricing structures differ across Europe.

Typically a PPA price consists of the following factors:

Average price of

representative index

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For a multi-year PPA; how to correctly forecast those factors?

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Ancillary Services

▪ Imbalance can be caused by:

– Generator and/or network trips

– Control strategy

– Prediction errors for load and/or generation

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50 Hzfr

equency

Frequency Containment

Frequency Restoration

Inertia

0 30 900

t [s]

t [s]pow

er

0 30 900

Deployment of balancing capacity

Frequency response

System response during trip of generator

<50 Hz

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rEVolt – feasibility for second life batteries

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▪ Received 10 battery packs with

software errors

▪ failure analysis:

– Battery cells in good condition

– Cell BMS is intact

– Main BMS/EMS is no longer

working

▪ Raspberry Pi can be used as new

BMS/EMS

– Easy to program, but communication

with cell BMS is essential

▪ New power electronics are needed for

stationary application

▪ Power electronics and refurbishing

cost are a significant part of the

second life application

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rEVolt – Business case analysis

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Assumptions:

▪ About 100 EUR refurbishing cost

per kWh

▪ System requirements in year 15

are 1 MW/1MWh

– Second life system at 70%SoH

need to be 5.7 times bigger

than the new system

▪ EoL is 50%

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Out of the rEVolt project successful business for start-up Time Shift Energy Storage

8https://www.timeshiftstorage.nl/

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Safety concerns about (second life) Li Ion batteries

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www.mpoweruk.com

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Li-ion systems: dealing with fire

▪ Risk

– Flammable components: organic electrolyte, anode/cathode, packaging

– Several possible causes: overheating, internal shorts, external fire, …

– Several effects: damage to / loss of system, external damage, toxic gases, …

▪ Mitigation measures

– Containment (system design)

– IEC 62619: “fire must be contained inside the system” (not defined…)

– Industry, DNV GL: “fire should be contained to module/rack”

– Suppression systems

– No adequate single extinguisher solution, no industry consensus; compromise

– Issue: cool with water (stop spreading, emissions), or allow to burn

– Ventilation: explosive/toxic gases (burnt plastics)

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See also: Considerations for ESS Fire Safety, public report for Consolidated Edison, DNV GL (2017)

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Testing, verification and certification

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https://www.bredenoord.com/en/news/met-de-big-battery-box-is-grootschalige-energieopslag-nu-ook-mobiel-beschikbaar/

https://www.dnvgl.com/news/ateps-battery-storage-system-receives-gridstor-conformity-statement-from-dnv-gl-86986

https://www.dnvgl.com/news/acciona-receives-the-world-s-first-grid-scale-energy-storage-certificate-by-dnv-gl-118466

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SAFER, SMARTER, GREENER

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Koen Broess

Koen.broess@dnvgl.com

+31646713810