Computer-Aided Assessment of Green Transportation Policies to Accelerate Taiwan's Energy Transition

Road transport is one of the hardest parts of Taiwan's economy to decarbonize — and one of the most distinctive, because scooters, not cars, dominate its roads. The government's 2050 Net-Zero Pathway sets ambitious electrification milestones, but whether those milestones actually put the sector on a net-zero trajectory is a quantitative question that had no systematic answer for Taiwan. This completed MOST (now NSTC) project (2020–2022) built the tool to answer it.

The project developed a computer-aided, Taiwan-specific vehicle fleet model: a bottom-up framework that tracks all eight road-vehicle types — private cars, scooters, business cars, taxis, heavy- and light-duty trucks, and urban and non-urban buses — from sales and stock turnover through to energy demand and life-cycle greenhouse-gas emissions out to 2050. Crucially, it captures the features that make Taiwan unusual, including the inverse-U ("motorcycle Kuznets curve") relationship between scooter ownership and income, and it uses bootstrap resampling to attach 95% confidence intervals to every projection rather than reporting single-point estimates. Fuel-cycle emission factors are drawn from a localized GREET-Taiwan model spanning well-to-pump and pump-to-wheel stages.

Applied across policy scenarios — a reference case, the current EV roadmap, and an EV roadmap paired with a cleaner grid — the model reaches three conclusions. First, Taiwan's total fleet follows an inverted-U trajectory, peaking near 22.4 million vehicles around 2032 before declining to about 20.5 million by 2050 as the scooter and freight markets shrink; electric vehicles reach roughly 80% of stock by 2050. Second, this electrification is necessary but not sufficient: 2050 direct emissions are modeled at about 8.4 Mt per year — 70% below the reference scenario, yet still 163% above the transport sector's 3.2 Mt net-zero target. Third, electrification shifts the carbon burden from tailpipe to power plant, so the transport target is only reachable when vehicle policy and grid decarbonization advance together.

The findings translate into concrete policy guidance — a more aggressive phase-out of fossil-fuel vehicles, inclusion of non-urban buses in the electrification roadmap, explicit coupling of transport and power-sector decarbonization, and continued fuel-efficiency gains for conventional vehicles until EVs reach cost parity. The fleet model and its scenario library became the analytical foundation for the E3 Center's subsequent work on sector coupling between electricity and transport.