cost effective electric bus - cenex lcv

Commercially confidential ‐ Property of Equipmake Ltd

Cost Effective Electric Bus


Equipmake Limited

• 25 Employees• Based at Hethel Engineering Centre, Norfolk• Currently developing prototypes and pre production

Future• Production Q1 2020 (100’s PA)• Manufacturing c 3,000 Units PA by 2022• Ariel, Bus, Other Niche• High volume licence

Core Competences• System & Vehicle Simulation• Power Electronic & Control System Design• Functional Safety• Permanent Magnet Motor Design & Development


Electric Buses ‐ Why Bother ?

• Pressure Globally on Cities to improve air quality • 4 Major Cities to ban diesel vehicles by 2025

• Paris, Mexico City, Madrid & Athens will implement ban• WHO says 3 million deaths PA linked to air pollution• Campaign for London to follow suit by 2025

BUT

• Electric buses are a solution but currently too expensive / heavy• Main issue is cost & mass of Batteries• Easiest way to improve this is to fit less batteries !

• Opportunity charging • Cost of infrastructure• Loss of flexibility

• Better energy Management ?


Business Case

• EV Bus can be cheaper than diesel between 5 – 10 years• Batteries will need replacing within 10 years• Cost comparable with diesel with battery replacement ?

• Need to warrant battery life

Diesel bus business case assumptionsAverage Diesel Consumption 7 mpgNet Fuel Cost after BSOG £0.70 /litreDiesel Maintenance Cost (Oil, Brakes etc) £0.10 /kmElectric bus business case assumptionsElectric Maintenance Cost £0.02 /kmLCEB Incentive £0.06 /kmElectricity Cost £0.10 /kWhElectricity Consumption 2.00 kWh/mile

City Suburban

Miles / annum 30000 60000

Fuel Cost £13,620 £27,240

Diesel Maintenance Cost £4,800.00 £9,600.00

Electric Maintenance Cost ‐£960 ‐£1,920

Electricity Cost ‐£6,000 ‐£12,000

Saving £11,460 £22,920

LEB Incentive £2,880.00 £5,760.00

Total £14,340 £28,680

Over 5 years £71,700 £143,400

Excluding LEB incentive £57,300 £114,600

Over 10 Years £143,400 £286,800

Excluding LEB incentive £114,600 £229,200


Where does the Energy Go ?

Traction• Motors / inverters• Rolling resistance• Mass• System Efficiency

Auxiliaries• Steering• Braking / Suspension / Doors (air compressor)• Lighting• Wipers

HVAC (Heating, Cooling & Ventilation)• Passenger comfort & safety• Conduction / insulation• Passenger load


Full Vehicle Simulation

• Separate Traction & Thermal Models• Traction model includes

• Battery Model• Electric Motor & Power electronics maps• Powertrain system losses• Vehicle Mass• Effect of terrain (hills)• “Backward looking” drive cycle

• Thermal Model includes• Solar load

• Conduction /radiation through glass• Conduction radiation through bodywork• Effect of passenger loading• Ventilation

• ASHRAE Standards• Variable passenger loading


Simulation Results

Assessment Criteria• Gains from baseline assessed for mass and cost variance against batteries• Battery installed baseline

• £266 / kWh• 7.2 Kg / kWh

Effect of Mass• Simulation run with HVAC off (best

case)• Reducing Mass by 1,000 kg results in

8kWh saving

• £ heavier weighting that kg !


Baseline Results• 12.5 Tonne vehicle• 15 Hour Cycle (165 miles)• Hottest & coldest days of the year• Ashrae recommended ventilation rates• 80 Passengers

448 kWh 494 kWh

Main Issue is HVAC

Simulation Results


Learning from Other Industries

Commercial Aircraft• High Occupant Density• Pressurised to 8,000 ft• Low humidity

• ASHRAE recommends 3.5 l/sec/passenger ventilation

Large Buildings• Low Occupant density• Use of PCM panels• Use of heat exchangers


Breakdown of Energy

• 100W / person heating• Conduction not significant• Gains through use of “energy efficient” glass

• Potential 12kWh saving with no weight gain

Total energy in 24hrs

Hot Case (kWh) Hot Case (kWh)Cold Case (kWh)

Cold Case (kWh)

Cooling Heating Cooling Heating

191.298 ‐0.007 0.316 ‐182.373 373.994 186.997 191.298 Reference 346.5 Reference Reference

193.179 ‐0.012 0.376 ‐181.536 375.103 187.5515 193.179 ‐1.881 440 93.5 ‐20.12

183.991 ‐0.001 0.204 ‐183.686 367.882 183.941 183.991 7.307 440 93.5 78.15

179.253 ‐0.08 6.773 ‐129.991 316.097 158.0485 179.253 12.045 352 5.5 2190.00

172.257 ‐0.04 5.555 ‐130.831 308.683 154.3415 172.257 19.041 440 93.5 203.65

163.842 ‐0.009 4.178 ‐132.368 300.397 150.1985 163.842 27.456 423.5 77 356.57

170.012 ‐0.029 5.209 ‐131.314 306.564 153.282 170.012 21.286 423.5 77 276.44

167.75 ‐0.029 5.168 ‐130.213 303.16 151.58 167.75 23.548 533.5 187 125.93

161.453 ‐0.007 4.043 ‐131.349 296.852 148.426 161.453 29.845 533.5 187 159.60

Inner Outer

3mm CLR 3mm VG10 151.23 ‐0.03 6.109 ‐116.847 274.216 137.108 151.23 40.068 660 313.5 127.81

4mm GRY 4mm GRY 163.616 ‐0.118 9.281 ‐113.711 286.726 137.108 163.616 27.682 880 533.5 51.89

3mm CLR 3mm GAL 154.863 ‐0.038 6.857 ‐116.21 277.968 143.363 154.863 36.435 660 313.5 116.22

4mm CLR 4mm GRY 165.648 ‐0.136 9.763 ‐113.402 288.949 138.984 165.648 25.65 880 533.5 48.08

4.85mm Grey Energy Advantage

4.85mm Grey Solar‐E

IGU

Highest ABS(kWhr)

Saving ref 3.15mm LG (kWhr)

4mm Grey

Coated Monolith3.2mm Light Green Energy

Advantage4mm Clear Solar‐E

3.85mm Grey Solar‐E3.85mm Grey Energy

Advantage

Glass Type Total Avg.

Uncoated Monolith

3.15mm Light Green

4mm Clear

Monolith ‐ General

Weight for 44m^2 (kg)

Weight gain ref 3.15mmLG (kg)

Specific energy saving

(Whr/kg)


HVAC Options

Heat Pumps• Conventional HVAC solution• COP 2 – 3 for automotive applications• Built environment quotes COP up to 5• COP depends on conditions (Humidity,

temp difference)• COP of 2.5 = 2.5kW heat for 1kW

electrical energy

Thermal Energy Storage• Phase change material options• Specific energy 10kg / kWh• Need different material for heating and

cooling• Cannot replace heat pump but part of

overall solution


Nitrogen Heat Engine• Specific heat of vapourisation 18 kg/kWh• Cost £0.40 / kWh vs £0.10 kWhe electricity• Complex cryogenic storage required

Ventilation Control• Forced ventilation required to maintain CO2 levels

and passenger comfort• Fixed levels for high passenger loadings will

consume excess energy at low loadings• Significant savings if ventilation can be varied with

passenger loading

HVAC Options


HVAC Options

Thermal Energy Recovery• Average electrical power for city cycle = 30kW• Assume 90% efficiency so 3kW heat rejected• Potential 45kWHr (18kWh) saving in cold case

recycling waste thermal energy

Heat producing drivetrain components

Heat users and storage

External radiator for summer use

HVAC using heat pump optimised for maximum COP, with smart ventilation control and thermal energy recovery can reduce battery requirements


Simulation ResultsUse of Heat Pump

• 12.5 Tonne vehicle• 15 hour cycle (165 miles)• Variable Passenger Loading (variable ventilation)• Hottest & coldest days of the year• Ashrae recommended ventilation rates• Heat pump COP 2.5

289 kWh 273 kWh


Ancillaries24V Supply options

Assuming 2kW for 15 hours = 30kWh• DC – DC Converter

• 95% efficient• Uses 31.6 kWh

• High Efficiency Alternator• 80% efficient• Uses 37.5 kWh

• 6 kWh saving for DC‐DC but alternator lower cost

Compressed air Options• Wabco Ecomp

• Conventional piston compressor with EM

• Gardner Denver ROL M Vane compressor• Conventional clutched piston compressor

driven from gearbox – Lower cost

• 120,000 rpm Twin Turbo compressor under development

commercially confidential property of Equipmake Ltd

IDP14 CELEB Project• 12 m single deck , 3 door• 300kWh battery pack (4 x 75kWh)• 2 x 200kW motors• 2 speed gearbox• 12,200kg Kerb Weight• Smart HVAC Control


Thank You

cost effective electric bus - cenex lcv

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