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Guidelines for Battery Electric Vehicles

in the Underground - Mine Design

April 30th, 2017

Presented By: Alain Richard Cheryl Allen

Electrical Engineer Principal Engineer – Ventilation

BESTECH Vale Ontario Operations

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Introduction

• Alain Richard– 6 years with BESTECH– Power System Studies

– Feasibility Study

– Ventilation Control System

Studies

– Electrical Design on the

Onaping Depth project

• Cheryl Allen– 30+ years in mining

– 16 years with Vale

– Mining Engineer

– Ventilation Design

– Research Studies

– BEV for Sudbury mine

projects

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Agenda

• Introduction and Intent

• Mine Layout and Infrastructure

• Personnel Movement

• Other Electric Equipment

• Charging Infrastructure

• Ventilation and Cooling

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Introduction and Intent

• First assumption: BEV mines will be different

than diesel mines

• Second assumption: Greenfield and brownfield

mines have different opportunities to

incorporate BEVs

• Intent: This is not a mine design 101 but rather

points to ponder when designing a BEV mine

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Mine Layout and Infrastructure

• Anticipated challenges to address:– Range limitation on a single charge

– Emerging technology (depending on the vehicle size)

– Different design questions/requirements

– Changing perspective of mine owners, operators and

designers

– Shift in maintenance resources

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Ore/Waste Handing System (OWHS)

• OWHS large energy consumer

• Multiple design trade-offs required

• Need to ensure BEVs do not have a negative

impact on the OWHS

• Impact of downhill haulage

• Impact of uphill haulage

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Regenerative Braking – the good

• Diesel vehicles convert all kinetic energy into heat

• With BEV it is possible to convert some of the kinetic energy back into electric energy while generating some heat

• Potential advantage:– Longer BEV range – Smaller Batteries

– Higher efficiency – Reduced heat production

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Regenerative Braking – the bad

• Dis-advantage:– Need proper planning and/or vehicle design to

prevent overcharging

– Might need braking resistor and/or regular brake

system

– Mine design may reduce full potential from

regenerative braking• Ex. Brownfield mine

– Experience is required to fully understand the

potential

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Vehicle Parking

• Typically not a constraint in the design for a

diesel fleet

• With BEV, parking will be based on the charging

strategy and needs to be carefully laid out

• Change in workforce culture

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Vehicle Parking

• A mine monitoring system would ideally track

the location and status of every BEV throughout

the day

• Need to remove the chance of a worker starting

a shift with a discharged battery

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Personnel Movement

• Whether the mine is shaft access or portal

access, changing to BEV needs to consider not

just the movement of ore/waste, but also of

people.

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Shaft Access

• Near shaft parking– Access vehicles via walking

– Requires sufficient parking locations and chargers

near shaft

• Mining level parking– Such as Jumbo, Bolter…

– Need to transport workers to vehicles

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Shaft Access

• Personnel carriers – Access personnel carriers via walking

– Transport workers to the mining levels or distributed

parking locations

• Combination– Find the best balance for the application

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Ramp Access

• Group travelling is strongly encouraged– Increase efficiency of travel

• Long uphill travels -> very demanding on

batteries

• Long downhill travels -> could be problematic

with regenerative braking

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Personnel Movement – Summary

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Equipment Groups

• Charge-while operating equipment group

(Tethered)

• Load Haul Dump (LHD) Machines

• Alternate haulage methods

• Auxiliary Vehicles

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Tethered Equipment

• Vehicles that are typically plugged into AC power while performing work– Bolters– Scalers– Jumbos…

• Move with diesel or battery power

• Charging via AC cables– Similar to some residential BEVs– Smaller battery

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Tethered Equipment

• Without an on-board charger– Ensure charger access

– Potentially more chargers required

– Larger battery

• Key to review the duty cycle of the battery

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Other Electric Equipment

• Load Haul Dump (LHD) Machines– Mine-level grades, charging philosophy, fully tethered,

hybrid-powered, inductive charging, trolley-assist

charging

• Alternate haulage methods– Conveyors, electric-powered trains, trolleys,

monorails, RailVeyorTM and continuous haulage

systems

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Charging Infrastructure

• Production is dependent on capacity to have

fully charged batteries

• Dependable charging infrastructure that fit for

purpose

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Design Prerequisites

• Questions to ponder:– Shifts per day?

– Duration per shift?

– Equipment expectation?

– Equipment capacity?

– Number of chargers?

– Types of chargers?

– Opportunity charging?

– Charging philosophy

– Special needs? • Ex. grader

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Design Prerequisites

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Charging Methods

• Simplified view of charging methods:

If battery running time > shift length -> shift-change charging

If battery running time ~ shift length -> shift-change charging + opportunity charging

If battery running time < shift length -> battery swapping or in-shift charging

• In reality, other factors will come into play and

affect the charging method

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Charger Diversity

• Spectrum of possible scenarios– Dedicated charger per equipment

– Limited to a few types of chargers

– One size fits all

• To balance a successful implementation and

prevent limiting innovation, a few types of

chargers will likely be required for each mine

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Opportunity Charging

• Scenario 1:

• Opportunity: 2×30 min. lunch break

+ 6×10 min. bio break = 2 h/day

• Typical shift-change: 2×2h = 4 h/day

– Conclusion:

• A dedicated opportunity charger would have half

the utilization than a shift-change charger

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Opportunity Charging

• Scenario 2, staggered lunch breaks, dual purpose

chargers

• Opportunity: 4×30 min. lunch break

+ 6×10 min. bio break + 4h = 7 h/day

• Typical shift-change: 2×2h = 4 h/day

– Conclusion:

• A shared charger could have nearly double the

utilization than strictly a shift-change charger

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Opportunity Charging

• Scenario 1, 50kW charger & 100kW battery

• 30 min. lunch = 25kW or 25% of charge

• Shift-change: 2h = 100kW or 100% of charge

– Conclusion:

• Interesting option to top-up the battery

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Opportunity Charging

• Scenario 2, 100kW charger & 100kW battery

• 30 min. lunch = 50kW or 50% of charge

• Shift-change: 2h = 100kW or 100% of charge

– Conclusion:

• Interesting option to reduce battery size

• Can reduce “range anxiety”

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Charging Stations

• Located near equipment; as recommended by

the OEMs

• For Mine Engineers, chargers can be viewed as

variable frequency drives

• Need to control:– Dust – Humidity – Heat

– Vibration – Percussion blast – Water

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Swap-out Stations

• Goal of a swap-out station is to provide a full

charge in a short amount of time -> similar to

diesel re-fueling

• Proper planning of vehicle traffic is key to

prevent congestion

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Swap-out Station Design

• Size of facility

• Crane system to remove and install batteries

– Must be compatible with all BEV types that use the

system

• Sufficient chargers in proximity

• Sufficient spare batteries

• Potential rockmass quality issues due to size of

excavation

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Power Distribution Considerations

• Incoming voltage is typically 480-1,000V, 3 phase

• Typically have an isolating transformer

• Harmonic producing device

• Need to consider upstream transformer sizing:– Large enough to address the harmonics

– Prevent oversize due to the low utilization rate of

chargers, especially if using shift-change charging

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Ventilation and Cooling

• Iterative approach between mine and ventilation

engineers

• Criteria to base the Ventilation design for BEVs– Temperature, dust, air velocity, clear blast gases

– Mine life, production profile, OWHS…

• Some differences:– No need to dilute diesel particulate

– Heat sources

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Air Volume

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Regulations

• Air quality is typically regulated by various

agencies:– Federal and local regulations

– Internal mining company standards

• The mine air volumes will be influenced by the

regulatory requirements

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Equipment Fleet

• Need to know:– Quantity of each type of equipment

– Power rating for each type of equipment

– Anticipated utilization

• Need to work with manufacturers to determine

the heat generation

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Heat Load

• Need to consider all heat sources:– All electrical equipment, including:

• Mine power centres, transformers, motors, VFD, chargers…

– Mobile equipment• Including batteries

– Auto compression

– Wall rock

– Any other sources

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Heat Load – Chargers

• Typical heat losses from charging equipment are

5-10%, but should be obtained from vendors

• Depending on placement of chargers, hot spots

might be created in the mine– 1x50kW charger, rated 5% losses, operating will

generate 2.5kW of heat, which can easily be dealt with

– 4x400kW chargers, rated 10% losses, will generate

160kW of heat, which may be challenging to dissipate

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Dust Control

• Reduced air volumes may not be sufficient to

remove dust contaminants, depending on

velocities

• Needs to be reviewed and may limit air volume

reductions

• Drift sizes, air volume and localized air

recirculation may need to be reconsidered

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Dust Control

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Blast Gas Clearing

• Time required depends on the air speed

• With a reduced airflow requirement, the time

required may become longer than desired

• Important to review the clearing times during

the design stage

• Considerations for capacity to increase airflow

duing blast clearing– VFD, louvers, automated ventilation control system

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Air Monitoring

• Determine the real-time monitoring

requirements

• Place instruments accordingly

• Consider maintenance and access to the

equipment

• Typical sensors include:– Carbon monoxide, sulfur dioxide, nitrogen oxides,

dry-bulb temperature, humidity, air volume

• Dust is not commonly measured in real-time

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Controlled Recirculation

• Typically limited due to the safety and health

implications in diesel mines

• BEV presents an opportunity to use controlled

full or partial recirculation

• If recirculation is part of the design, sufficient

fixed monitoring is required to ensure regulatory

compliance of air quality

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Ventilation Design Process

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Safety

• High level risk

assessment is

recommended to

understand the total

mine design risk with

BEV

• More detailed

assessments for critical

risks identified

• Include items such as:– Safety training

– Noise

– Power and voltage

– Air quality

– Heat

– Fire

– Geotechnical

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Mine Design Conclusion

• Designing a BEV mine

offer multiple

opportunities

• Need to understand

the topics to be

explored and reviewed

prior to

implementation– Both greenfield and

brownfield mines

• BEV mine designers

need to ask themselves

new questions during

the design process of a

battery mine

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Questions?

Thank you / Merci

Alain Richard Cheryl Allen

alain_richard@bestech.com cheryl.allen@vale.com

705-675-7720 ext. 283 705-682-6857