Study of the Energy Efficiency and Greenhouse Emissions from Motorcycles Powered by Electric and Internal Combustion Engines

This paper reports and compares the performance of five motorcycles, four of them powered by Internal Combustion Engine (ICE) and one by an Electric Engine (EE). The power grade of those vehicles represents more than 80% of Brazilian motorcycle fleet. Motorcycles are submitted to standard routines, in accordance with regulations established by PROMOT (Control of Air Pollution for Motorcycles and Similar Vehicles). Main output parameters allowed for the assessment of their energy performance in respect to the energy source, followed by their greenhouse gases emission potential due to CO₂, CH₄ and N₂O. The paper presents regulated emissions results for CO, THC and NO_x, provided by EE and ICE engines. Different ICE motorcycles are tested, and fueled by a range of ethanol/gasoline contents from 22 to 100%, allowing to analyze the influence of the renewable biofuel on the motorcycle energetic efficiency and emissions. The EE motorcycle test requires taking into account the battery load profile along the essay. ICE motorcycle efficiencies ranged from 13% to 17%, approximately, whereas EE displayed 47%. A novel methodology is proposed to estimate the grid penalty imposed to the amount of work performed by each of the motorcycles. Results showed that electrical motors are still less energetic demanding then liquid fueled engines, but with a smaller difference among them. A Top to Bottom Energy ratio is proposed to express energy penalties, and result for electricity is 4.12 and for the average liquid fuels is 7.14, meaning that a unitary quantity of energy produced by the motorcycle needs approximately 4 times more of it from the electrical grid or 7 times more from the liquid fuel chain. Results reveal significant differences related to greenhouse gas (GHG) generation for both technologies (ICE and EE) and influence of the use of ethanol and its mixtures.