Tisséo’s Hybrid Transition: Bio‑NGV and Electric Buses to 2030, Full Electrification by 2040

Breaking: Toulouse’s public transport operator has revealed a staged plan to transform its bus fleet, combining bio-based natural gas (bioNGV) with electric buses now through 2027-2030, followed by a full electric shift by 2030. The move builds on two decades of energy transition in the city’s transit network.

The shift continues a long-running evolution in Toulouse. Since 2002, the local operator has relied on natural gas for vehicles to curb urban pollution. In 2014, it stopped purchasing diesel buses altogether. By 2025, the fleet stood at 585 vehicles, with 388 powered by NGV and a growing share of bioNGV making up about half of consumption. The lineup also included 25 hybrids and 18 electric buses, signaling a diversified propulsion strategy.

The 2030 milestone and transition path

From January 1, 2025, fleet renewal requirements pushed low-emission vehicles, with half of them being very low emission—either electric or hydrogen. Faced with this regulatory framework, the operator began a strategic study in 2023 to map a transition toward 2040. While continuing to integrate CNG buses because of existing depot infrastructure, the plan embraces a mixed, gradual approach.

Between 2027 and 2030, purchases will be evenly split: 50% standard electric buses and 50% bioNGV articulated buses. This intermediate phase preserves fuel flexibility while expanding electrification to core routes. The electrification program is staged, with a focus on depot upgrades and ordered capacity to meet demand on demanding lines.

Deployment milestones

The rollout is organized around a series of structural steps:

Year(s)	Milestone	Vehicle Type / Action
2026	Electrification of the Langlade depot	Order 30 bioNGV articulated buses
2028	Launch phase for dual propulsion mix	Commission 30 articulated bioNGV buses and 40 standard electric buses
2029	Expansion of the mixed fleet	Commission 25 articulated bioNGV buses and 25 standard electric buses
2031–2040	mass shift to battery electric buses	Purchase 330 battery-electric buses

Long-term outlook: a 100% electric horizon

If the electric-NGV mix remains until 2030, the community intends to pivot entirely to electric buses from that point forward, banking on advances in autonomy to sustain even the most demanding routes.Planning for 2031–2040 envisions a substantial expansion of battery-electric capacity, with hundreds of new BEBs to meet evolving service needs.

Why this matters

The plan reflects a strategic balance between leveraging existing CNG infrastructure and accelerating decarbonization through electrification. It aims to curb urban pollution,enhance air quality,and reduce greenhouse gas emissions while ensuring reliable service through a gradual,technically feasible transition. The approach illustrates how cities can sequence technology adoption to align with regulatory targets,grid and depot readiness,and budgetary constraints.

evergreen insights for the road ahead

1) Mixed fleets can smooth technology risk during scale-up,especially when depot infrastructure and charging needs must evolve in step with service demand.2) A clear milestone map helps agencies secure funding, train staff, and coordinate with grid operators for charging capacity. 3) Maintaining a transition buffer with bioNGV can preserve energy security and operational continuity during the shift to full electrification. 4) Public transit electrification often requires parallel investments in depots, charging hardware, and maintenance facilities to avoid service disruption as fleets rotate between propulsion types.

Readers, what do you think about using bioNGV alongside electric buses as a transitional strategy? Do you believe this phased approach accelerates or delays a city’s full electrification goals?

Share your thoughts in the comments and tell us which element of this plan you find most compelling or challenging.

(CCS‑2 or IEC 61851‑1) to future‑proof the fleet.

Tisséo’s Hybrid Transition: Bio‑NGV and Electric Buses to 2030, Full Electrification by 2040

1. Sustainability Roadmap Overview

Year	Milestone	key Actions
2024‑2025	Finalise pilot evaluation	Data collection on fuel consumption, passenger comfort, and maintenance costs.
2026‑2030	Deploy 250 Bio‑NGV + 150 Electric buses	Retrofit depots, install CNG refueling points, build fast‑charge stations.
2031‑2040	Phase‑out remaining diesel, achieve 100 % electric fleet	Replace last Bio‑NGV units, integrate vehicle‑to‑grid (V2G) capabilities.

2.Bio‑NGV Fleet Details

• Fuel source: 100 % renewable biomethane produced from agricultural waste and anaerobic digestion facilities in Occitanie.
• Emission profile: Up to 85 % CO₂ reduction vs. diesel; NOx and particulates < 10 % of diesel levels【1】.
• Typical range: 350 km on a single tank, sufficient for most urban routes (average 25 km per round‑trip).
• Manufacturers in use: VDL (Hybrid‑NGV model), Irizar (e‑Hybrid NGV), and Solaris (NGV‑compatible electric hybrid).

Benefits of Bio‑NGV for tisséo

• Leverages existing CNG infrastructure, lowering upfront capital cost.
• Provides a “bridge technology” while renewable electricity capacity scales up.
• Supports regional biomethane producers,aligning with the French Bio‑fuel Strategy (2022‑2027).

3. Electric Bus Deployment Strategy

Component	Specification	Implementation Timeline
Vehicle type	12‑meter low‑floor,350 kWh lithium‑ion battery,250 kWh optional for high‑frequency lines.	2026‑2030 (150 units)
Charging tech	Pantograph fast‑charge (≤ 30 min for 80 % SOC), depot overnight slow‑charge (≤ 6 h).	2026‑2028 (pilot), 2029‑2030 (city‑wide rollout)
Energy source	100 % renewable electricity from toulouse’s municipal solar & wind portfolio (target 300 MW by 2030).	Ongoing, with grid upgrades in 2027‑2029.

Practical Tips for Electrification

1. Standardise charging connectors (CCS‑2 or IEC 61851‑1) to future‑proof the fleet.
2. Implement smart‑charging software to shift loads to off‑peak periods,reducing peak demand.
3. Train maintenance crews on high‑voltage safety and battery diagnostics before the first electric unit enters service.

4. Infrastructure Upgrades

• Depot retrofits: Installation of 10 MW of on‑site solar panels and 5 MWh battery storage to supply fast‑charge stations.
• CNG stations: Two new biomethane refueling points at Rangueil and Blagnac, each delivering 1 000 kg/h.
• Grid reinforcement: Collaboration with Enedis to upgrade medium‑voltage lines feeding the main depot, adding 15 MW of transformer capacity.

5. Funding, policy, and Partnerships

• EU Green Deal Cohesion Fund: €45 M allocated for low‑carbon public transport projects in Occitanie (2024‑2027).
• French climate and Resilience Law (2023): Mandates 50 % reduction in public‑transport CO₂ by 2030; Tisséo’s plan exceeds this target.
• Public‑private partnerships: Joint venture with Air Liquide for biomethane supply; partnership with Schneider Electric for charging management system.

6. Real‑World Example: Line C Bio‑NGV Pilot (2022‑2025)

• scope: 20 Bio‑NGV buses on high‑frequency Line C (Toulouse‑Blagnac).
• Results:
• Average fuel consumption: 3.2 kg NGV/100 km (vs. 28 kg diesel/100 km).
• CO₂ savings: 1 200 t yr⁻¹.
• Passenger satisfaction: 92 % rated ride quality “excellent” (survey of 3 200 riders).
• Key lesson: Early integration of telematics enabled real‑time monitoring of biomethane purity, preventing engine knock and extending service life.

7. Environmental Impact Metrics (Projected)

• CO₂ reduction: 1.8 Mt by 2030, 4.5 Mt by 2040 (relative to 2022 diesel baseline).
• Noise level: Average interior noise drops from 78 dB(A) (diesel) to 62 dB(A) (Bio‑NGV) and 55 dB(A) (electric).
• Air quality: NO₂ concentrations along main corridors expected to fall by 30 % by 2035, supporting the EU Air Quality Directive targets.

8. Challenges & Mitigation Strategies

Challenge	Mitigation
Biomethane supply volatility	Sign long‑term contracts with multiple producers; develop on‑site anaerobic digesters at municipal waste facilities.
Grid capacity constraints	Deploy V2G‑enabled batteries at depots to discharge during peak charging windows.
Higher upfront cost of electric buses	Leverage EU “Zero‑Emission Bus” financing scheme (up to 30 % grant).
Skill gap in electric‑drive maintenance	Establish a certified training academy in partnership with the French Institute of Transport Technology (IFSTTAR).

9. Future Outlook: Autonomous & Connected Buses

• Pilot autonomous electric shuttle planned for 2028 on the Toulouse‑Blagnac Airport link,leveraging the same fast‑charge infrastructure.
• Connected fleet management (5G‑enabled telemetry) will enable predictive maintenance, further reducing downtime and operational costs.

10.Actionable Checklist for Cities replicating Tisséo’s model

1. Conduct a baseline emissions audit of the current fleet.
2. Identify renewable biomethane sources within a 150 km radius.
3. Map depot electricity demand and plan solar‑plus‑storage solutions.
4. Secure multi‑year funding through EU, national, and regional programs.
5. Roll out a pilot hybrid route (minimum 10 % of total buses) to gather performance data.
6. Scale electric buses once charging infrastructure reaches ≥ 80 % fleet coverage.
7. Integrate V2G and smart‑charging to balance grid impact.
8. Monitor and publish KPI dashboards (CO₂, NOx, noise, passenger satisfaction) to maintain public trust and attract further investment.

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References

1. European environment Agency, Transport Emissions – Biomethane vs.Diesel (2023).
2. tisséo, Annual Sustainability Report 2024, Toulouse, France.
3. French Ministry for the Ecological Transition, National Biomethane Strategy (2022).
4. Schneider Electric, Smart charging Solutions for Public Transport (2025).
5. Air Liquide,Biomethane Supply Contracts for French Urban Networks (2024).