Technical Design Proposal (Draft 1)
Introduction
This proposal is written in response to an email calling for proposals for sustainable economic growth. It aims to provide LTA with a comprehensive overview 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.
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 standard gas combustion engines. They generally run cleaner and quieter than everyday vehicles that use gas combustion engines. The fully electric engine also has a higher efficiency of up to 90% as compared to its traditional counterpart (CITATION), thus providing economic savings.
Currently, Singapore’s construction companies are not utilising EVs for their excavators. 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 (CITATION). Caterpillar Pte Ltd are making use of electric excavators in Norway which reduce carbon emissions by 52 tonnes per machine, *as said by Veidekke’s construction director, Oivind Larsen (CITATION).
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.
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 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 as soon as possible, the industry will be able to enjoy the long term benefits sooner.
Lit review
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.
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. A typical excavator while running is around 87 dB. An electric runs much quieter at a range of 30-60 dB.
Excavators are mechanical machines used in the construction sector for excavating road works. They are piloted by a 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 get worse with bigger machines like excavators.
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.
Sound
A whisper is about 30 dB, normal conversation is about 60 dB, and a motorcycle engine running is about 95 dB. A typical excavator while running is around 87 dB. An electric runs much quieter at a range of 30-60 dB.
https://www.shutterstock.com/image-vector/decibel-scale-sound-level-volume-chart-1304692708
https://www.tractors.com.sg/blog/360-fuelefficiency-336gc
Cost for diesel excavator
20.94L x $2.58 = $54
This is for 1hr run time therefore it costs $54 per hour to run.
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.
300kwH x 25cents = $75
This is for 6hrs run time therefore it cost $12.5 per hour to run.
https://futurism.com/the-byte/electric-excavator-norway
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