Technical Report #Draft 2
Electrification of excavators to reduce production and operational cost.
Technical Report
Prepared for:
Land Transport Authority
1 Hampshire Road
Singapore 219428
Developed By:
Tang Chan Yee Chester (2101142)
Ng Chin Wai (2100640)
Htet Wailian Min (2100707)
Zulfadhli (2102220)
Singapore Institute of Technology
10 Dover Dr
Singapore 138683
March 2022
Table of contents
4.1.2 Cost of electrical excavator 11
4.2.2 Cost of electrical excavator 12
Letter of transmittal
Land Transport Authority
1 Hampshire Road
Singapore 219428
Dear Sir/Madam,
Re: Proposal to Implement Electric Excavator as an engineering solution to make excavators more efficient.
Yours sincerely,
Htet Wailian Min
On behalf of The Four Brothers
CVE1281 Effective Communication
Singapore Institute of Technology
Executive summary
This report summarises the research done by the Four Brothers team on the effectiveness of electric excavators that use electric engines compared to conventional excavators using gas combustion engines. An email was sent out to the students of the civil engineering degree programme in the Singapore Institute of Technology calling for proposals for engineering solutions. Four students from the programme formed the Four Brothers team and have come up with a proposal to replace traditional excavators with electric excavators. The benefits and limitations are outlined in later sections to depict the pros and cons of such an engineering project. The main focus is to propose to LTA a change in policy to require construction companies in Singapore to have at least 20% of their construction fleet to be electric in order to boost productivity, reduce maintenance and fuel costs, and project Singapore as a green city in the construction sector.
Following is a list of the objectives of this report:
Explain the motivation behind this report
Set the problem and its ideal proposal in stone
Benefits of this engineering solution
Possible limitations and its proposed solutions
Step-by-step methodology of implementing the proposal
Concluding statements and compliments
1.0 Introduction
This report is written in response to an email calling for proposals for engineering solutions. The main aim of this report is the implementation of electric vehicles as an engineering solution to make the excavators more efficient. It aims to provide LTA with a proposal of how electric excavators would benefit the country in the long run.
1.1 Background
The Four Brothers team’s focus is on sustainability and environmental protection. The team started off with the idea of changing common day garbage trucks to electric vehicles (EVs). However, through initial research, the team found out that this concept has already been implemented by Sembcorp Pte Ltd, one of the main companies in the waste management sector in Singapore. They have converted 20% of their garbage truck fleet to EVs and are planning to do more by 2030 (Sembcorp Industries, 2021).
Hence, as civil engineering students, the team has changed its field of focus to its area of speciality, the construction sector. The team has narrowed it down to excavators in road works specifically since excavators are one of the more prominent and heavily used vehicles in the sector.
EVs are vehicles that are fully electric-powered and use electric engines instead of the traditional combustion engines which make use of diesel. Currently, Singapore’s construction companies are not utilising EVs for their excavators.
Singapore’s 2030 Green Plan provides a road map to reinforce Singapore’s national sustainability efforts. The goals of this proposal are in line with the country’s efforts to achieve lower carbon emissions while providing much higher energy efficiencies. As western construction companies are already implementing electric excavators in their construction fleet, this technology would not be hard to come by and can be modified to fit local requirements. As such, by implementing this concept in Singapore’s construction fleet, the industry will be able to enjoy the long term benefits.
Case Construction Pte Ltd makes use of electric excavators that claim to provide the same efficiency as conventional diesel-powered machines while providing up to 90% in fuel and maintenance costs (Case Construction, n.d.). Caterpillar Pte Ltd are making use of electric excavators in Norway which reduce carbon emissions by 52 tonnes per machine (Lambert, 2019).
Therefore, this proposal is addressed to LTA to require construction companies in Singapore to have at least 20% of their construction fleet to be electric by 2030, in order to provide higher energy efficiencies, reduce environmental and noise pollution, and provide higher cost savings.
Lit Review
Excavators are mechanical machines used in the construction sector for excavating road works. They are piloted by an operator who uses joysticks on the excavator to control the mechanical arm of the machine, which operates using a hydraulic system. The arm then digs into soil and is able to carry it into its designated storage area, such as a dump truck. Traditional excavators use gas combustion engines which burn fuel to attain mechanical energy to carry out its tasks. This generates tons of carbon emissions through its exhaust pipe. It also creates noise pollution, largely due to the gas combustion engine causing excessive noise which gets worse with bigger machines like excavators.
Efficiency is the ratio of the total power input to a mechanical device to the total useful power output of the intended effect, measured in percentage(%) or kilowatts per hour (kWh). In this proposal, it would be the ratio of the conversion of potential energy in fuel or electrical energy in electricity, to the mechanical energy in the engine of the excavator, in order to allow the excavator to carry out its works.
Electric Vehicles (EVs) have higher efficiencies of 85% when converting electrical energy to mechanical energy, compared to conventional gas combustion engines with only 40%. They also reduce environmental and noise pollution through their fully-electric engines.
An ideal excavator would be one that is able to run efficiently on electrical energy. It would be much cheaper to run than diesel and no additional pollution to the environment. It would run much quieter than conventional excavators and be able to operate for long hours per charge cycle. It should have a familiar interface and operating procedures so that the drivers are able to transition smoothly to these new electric excavators.
The ideal excavator would be the Cat 320 Zline (see Figure 1). It is an excavator with a “fully electric drivetrain” and low “noise levels”. It is easy to operate and last 6 hours per charge cycle. (Cat 320 z-line, n.d.)
Figure 1
(Cat 310 z-line, n.d.)
1.3 Problem statement
Currently, Singapore’s construction companies do not utilise electric excavators. An ideal target would be 20% of their excavating fleet to be electric by 2030. 5
1.4 Purpose statement
This report proposes to LTA a change in regulations to require construction companies to have 20% of their excavating fleet to be electric by 2030, such that it reduces carbon footprint while producing similar results to traditional vehicles.
2.0 Solution
3.0 Benefits
3.1 Cost saving
Figure 2
Cost breakdown of running 2 different diesel excavators.
Home. Tractors Singapore. (n.d.)
Cost for diesel excavator
Home Tractors Singapore offers many types of excavators. For this report, we shall focus on the more fuel efficient model of the two (See figure 2)
20.94L x $2.90 (shell) = $60.73
This is for 1hr run time therefore it costs $60.73 per hour to run.
The cost of diesel is updated as of 10/03/22. Motorist.sg. (n.d.)
Cost for electric excavator
As of simple terms, the formula is: Size of battery (kWh) x Electricity cost of your supplier (pence per kilowatt-hour) = Cost to charge an electric car from absolutely empty to full. Houser. (2019)
300kwH x $0.414 = $124.2
This is for 6hrs run time for a 300kwH excavator. It cost $20.7 per hour to run.
150kwH x $0.414 = $62.1
This is for 6hrs run time for a 150kwH excavator. It cost $10.4 per hour to run.
Rate is calculated based on the SP Group public charging station using a 43kW AC charger, at $0.414 per kWh
Realiabiliy and maintenance
Reliable and durable, with less maintenance required as there are lesser moving parts in an electric vehicles, namely the motor and the crankshaft. Whereas, a diesel excavator would require many small complex parts to assist in the combustion process of a traditional vehicle. The electric motors rarely need a tune-up to maintain peak performance as everything is monitored by computers which are easily able to integrate and solve problems before they surface.
Lesser maintenance works would result in higher cost savings in the long run.
3.2 Cleaner
There are no exhaust gases released from an EV excavator as they are run by batteries. This would help lower down pollution in construction areas, this is beneficial especially around residential areas. The motors also run cool and eliminate heat in the cabin which provides a better working environment for the excavator operator.
This would result in a reduced carbon footprint in the construction industry. This would be in line with the Singapore Green plan 2030. Even Though we are targeting only 20%, there would be a significant reduction to the emissions produced.
3.3 Quieter
They generally run cleaner and quieter than everyday vehicles that use gas combustion engines. The fully electric engine also has a higher efficiency of over 85% as compared to its traditional counterpart with less than 40% (Alum, Boloor, Garcia, Statler & Valderrama, 2019), thus providing economic savings.
Sound is the vibration of the acoustic wave which is transmitted through a medium such as air and is received in the ear and perceived by the brain, measured in decibels (dB). A whisper is about 30 dB, normal conversation is about 60 dB, and a motorcycle engine running is about 95 dB. (See Figure 2) A typical excavator while running is around 87 dB (Environmental Protection Department, n.d). An electric excavator runs much quieter at a range of 30-60 dB
Figure 2
Daily activities described on the decibel scale.
Kaan, E. (n.d.)
3.4 Performance
Excavators generally need high torque power sources as its needed to move the hydraulic fluid under high compression to carry out heavy duty tasks (Lambertson, 2017). That is the main reason why they are powered by diesels. Diesels provide much higher torque than gasoline engines accessible at lower revolutions per minute (rpm). Now with the introduction of electric engines, much higher torque figures can be obtained at even lower rpms. (See Figure 3) This would boost the performance of the EV excavators as compared to traditional diesel excavators.
Another application of ev conversion is in the yacht industry. Yachts are typically very heavy vehicles and a high amount of torque is required to operate them. The company Elco states “The Elco EP Motor is pure torque, unlike a diesel that uses belts, pulleys, and many other moving parts. The diesel motors moving parts create losses in torque”.
Figure 3
(Elco Motor Yachts, 2020)
4.0 Evaluation
4.1 Limitations
4.1.1 Charging Speed
Lower price range of EV excavators can be helped by federal subsidies, this will certainly attract the construction companies. However, the companies might be worried about the recharge of EV excavators. Concerns could be the alternatives to charge the excavators and the recharge with speed and convenience.
Considering the process of refuelling conventional excavators, diesel delivery companies are able to provide the diesel top up services to construction companies weekly/biweekly depending on the tank capacity and frequency of the usage. However, for companies with EV excavators, they will have range anxiety for two reasons. Firstly, there are not enough charging stations for EV excavators. Secondly, it can take a longer time to charge an EV excavator.
One might wonder, why can’t we just have more EV charging companies to provide charging services. While reproposing for more EV charging companies can be a good idea. In comparison, a 60-kWh battery can travel 232 miles, while an 85-kWh battery can travel 300 miles. Battery of EV excavators typically ranges from 200kWh to 300kWh, with 85kWh battery, it takes 52 hours to charge from 0 to 300 miles. Therefore, with a 300kWh battery, it's equivalent to charging 184 hours (7-8 days). Hence, EV excavators can only be used bi-weekly.
Hence, the turnover rate of charging is longer, this means that there will be delays in the work, and decrease in work efficiency. The bottom line is that charging EV excavators poses different challenges in contrast to refuelling conventional excavators. This leads to more rethink in the geography of refuelling.
4.1.2 Cost of electrical excavator
One of the concerns that construction companies might have that make them reluctant to convert a portion of their fleet of excavators to EVs is that it is very expensive. Based on an article posted on constructionsales, it mentioned that the price of electric excavators are expected to be higher than traditional diesel-operated excavators. The JCB 19C-1E is an electric excavator which weighs about 1862kg and costs $80,000. (Chong, 2020) Primary research was done with a construction site manager from Ban Choon Construction. He mentioned that a similar mini excavator of similar weight and specifications cost around $65,000
4.1.3 Charging Points
Limited Charging points for EV excavators can cause an issue to the construction companies despite the lower price range that can be provided by the government subsidies. Companies need to plan on when and how to charge the EV when the battery is running low, how many EV and conventional excavators are being used during the project (target 20% to be EV). This is to ensure the project is running smoothly throughout. For conventional excavators, they are required to top up using diesel, this takes about 2-3 minutes to finish up. Hence, the concern is how to charge EV excavators when the battery is running low.
4.2 Solutions
4.2.1 Charging Speed
https://www.truecar.com/blog/how-long-does-it-take-to-charge-an-electric-vehicle/
4.2.2 Cost of electrical excavator
To offset the high cost of purchasing new electric excavators, subsidies are given to companies in the construction industry for using greener and more environmentally-friendly equipment for upcoming projects. Based on an article from Responsible Business, a scheme called Green and Sustainability-Linked Loans Grant Scheme (GSLS) was launched by the Monetary Authority of Singapore (MAS) which targets corporations of different levels to move towards a green and sustainable approach. These loans can be used for projects that utilise equipment that have lower emissions such as electric excavators. Upon hitting the specific sustainability performance goals, they will receive a lower loan interest rate.
4.2.3 Charging Points
Primary research was conducted with a construction site manager from Ban Choon Construction. He mentioned he has been involved in several projects, and pointed out that every construction site has a power grids. It's important when it comes to planning when the floor plan was given to him, he has to consider where to station the excavator so that it won't obstruct the traffic. He also mentioned the fact of having EV excavators, they need to plan on these EV excavators to be set on which location. EV excavators need to be charged when the battery is running low.
5.0 Methodology
6.0 Conclusion
References
Alum, Boloor, M., Garcia, S., Statler, A., & Valderrama, P. (2019, July 31). Electric Vehicles 101. Natural Resources Defense Council.
Auto Repair Gears. (2022, January 16).How Long Does It Take To Fully Charge A Tesla+ Tesla Battery Replacement Cost - Auto Repair Gears. https://autorepairgears.com/how-long-does-it-take-to-fully-charge-a-tesla-tesla-battery-replacement-cost/#:~:text=In%20comparison%2C%20a%2060-kWh%20battery%20can%20travel%20232
Case Construction. (n.d.) The industry’s first fully electric backhoe loader - The Case 580 EV.
https://www.casece.com/northamerica/en-us/products/backhoe-loaders/580ev-project-zeus
Cat 310 z-line. (n.d.). Retrieved March 14, 2022, from https://view.publitas.com/pon-cat/310-z-line/page/1
Chong, C. (2020, Aug 5). JCB 19C-1E electric mini excavator review. Constructionsales
Choo, C. (2021, June 16). Financing SMEs for Sustainability in Singapore. Responsible Business. https://www.responsiblebusiness.com/channels/sustainable-finance-news/financing-smes-for-sustainability-in-singapore/
Dolsak, N. and Prakash, A. (2021,May 5). The Lack Of EV Charging Stations Could Limit EV Growth. Forbes. Retrieved March 14, 2022, from https://www.forbes.com/sites/prakashdolsak/2021/05/05/the-lack-of-ev-charging-stations-could-limit-ev-growth/?sh=6048156a1317
Elco Motor Yachts. (2020, November 3). Retrieved March 12, 2022, from https://www.elcomotoryachts.com/our-technology/
Environmental Protection Department. (n.d.). Foundation Works. https://www.epd.gov.hk/epd/misc/construction_noise/contents/index.php/en/foundation-works/49-quieter-construction-equipment.html
Home. Tractors Singapore. (n.d.). Retrieved March 10, 2022, from https://www.tractors.com.sg/blog/360-fuelefficiency-336gc
Houser, K. (2019, January 30). This massive all-electric excavator has a 3.4 ton battery pack. Futurism. Retrieved March 10, 2022, from https://futurism.com/the-byte/electric-excavator-norway
Kaan, E. (n.d.). Decibel scale sound level volume chart stock vector (royalty free) 1304692708. Shutterstock. Retrieved March 10, 2022, from https://www.shutterstock.com/image-vector/decibel-scale-sound-level-volume-chart-1304692708
Lambert, F. (2019, January 29). Caterpillar unveils an all-electric 26-ton excavator with a giant 300 kWh battery pack. Electrek.
https://electrek.co/2019/01/29/caterpillar-electric-excavator-giant-battery-pack/
Lambertson, G. (2017, June 16). Excavator engines: Understanding the power and complexities of diesels in small excavators. Compact Equipment Magazine. Retrieved March 12, 2022, from https://compactequip.com/engines/excavator-engines-understanding-power-complexities-diesels-small-excavators/
Motorist.sg. (n.d.). Latest petrol price comparison in Singapore 2022: Motorist Singapore. Motorist.sg. Retrieved March 10, 2022, from https://www.motorist.sg/petrol-prices
Sembcorp Industries (2021, July 19). Sembcorp opens Singapore’s first solar-powered EV charging hub.
TrueCar Adviser.(2021,March12).How Long Does It Take to Charge an Electric Vehicle? TrueCar Blog. https://www.truecar.com/blog/how-long-does-it-take-to-charge-an-electric-vehicle/
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