When we stand at a bus stop waiting for public transport, few people think about what exactly makes the multi-ton colossus move forward. Question, what kind of fuel does the bus have?, ceased to be simple and unambiguous several decades ago. If earlier the answer was exclusively “diesel oil”, today the fleet of municipal vehicles is experiencing a real revolution, dictated by environmental standards and economic feasibility.
Modern urban and intercity transport is a complex engineering organism, where the choice of energy carrier affects everything: from the cost of a ticket for a passenger to the noise level in the cabin and the amount of exhaust gases. In this article we will analyze in detail the evolution of public transport engines, compare the efficiency of different types of fuel and look into the future, where, perhaps, the usual refueling nozzles will become history.
Diesel fuel: the timeless classic of public transport
For most of bus history diesel fuel remained the uncontested leader. This is explained by the physical properties of diesel fuel: high energy density and the ability to ignite from compression, which allows you to create powerful and high-torque engines without complex ignition systems. For heavy vehicles that constantly stop and start in the urban cycle, diesel torque is a critical parameter.
However, the use of diesel is associated with a number of serious problems that force engineers to look for alternatives. The main enemy remains emissions of nitrogen oxides (NOx) and particulate soot particles. Modern environmental standards Euro 5 and Euro 6 require a sophisticated exhaust gas purification system. No reagent required AdBlue (water solution of urea) modern diesel buses simply will not be able to pass certification.
Why did diesel dominate for so long?
Diesel engines have high efficiency (up to 45-50%), which is significantly higher than that of their gasoline counterparts. In addition, diesel fuel is less flammable during storage, and the infrastructure for its delivery has been established for decades.
It is important to note that fuel quality plays a key role in engine longevity. The use of low-grade diesel fuel leads to rapid failure of expensive fuel injectors and particulate filters.
- 🚌 High thrust at low speeds is ideal for a busy interior.
- ⛽ Well-developed infrastructure of gas stations around the world.
- 🌫️ Environmental problems require expensive filtration systems.
- ❄️ Risk of fuel waxing at extremely low temperatures.
Diesel remains the king of long-distance driving thanks to its long range, but in a dense city its days are numbered due to environmental restrictions.
Compressed natural gas: economic efficiency and ecology
The answer to the question is what kind of fuel does the bus have? Today, the most popular in large cities of Russia and the world, increasingly sounds like “methane”. Compressed natural gas (CNG) or Compressed Natural Gas (CNG) is methane compressed to 200-250 atmospheres. Converting bus fleets to gas can significantly reduce operating costs, since the cost of a cubic meter of gas is often two to three times lower than a liter of diesel fuel.
From a technical point of view, gas engines are quieter and cleaner. When methane burns, virtually no soot is formed, and emissions of harmful substances are significantly lower than those of diesel. This makes gas engine technology attractive for use in historical city centers with strict environmental restrictions. However, gas also has its own characteristics that require attention during operation.
The main difficulty is the need to install bulky high-pressure cylinders. They are usually located on the roof of the bus, which changes the center of gravity of the vehicle and requires strengthening the body structure. In addition, the range on gas is usually less than on diesel, which requires more careful planning of routes or the installation of additional tanks.
For drivers, switching to gas means changing their driving style. The gas mixture burns differently, and the acceleration dynamics may differ from the usual diesel one, especially when fully loaded with passengers.
Liquefied propane-butane: a niche solution for small forms
Unlike methane, which is stored in compressed form, propane-butane mixture (LPG or LPG) is stored in a liquefied state under less pressure. This fuel can more often be found on small class buses, such as GAZelle Next or Ford Transitused as minibuses. For large city buses such as LiAZ or MAZ, propane is used less frequently due to its lower energy intensity compared to methane.
The advantage of propane is a simpler storage system: the cylinders are lighter and do not require such high pressure as methane. This allows them to be placed more compactly, without occupying the entire roof of the vehicle. However, the economics of converting a heavy bus to propane are often lower than using methane, making it a less attractive option for large municipal fleets.
Safety when using liquefied gas requires strict adherence to regulations. The gas is heavier than air and if there is a leak, it will accumulate in low areas, creating a risk of explosion if there is a spark. Therefore, security systems, including gas valves and leakage sensors must be checked regularly.
⚠️ Attention: Refueling a bus with passengers inside is strictly prohibited by safety rules when using any type of gas fuel.
Electric traction: a quiet revolution in urban transport
Electricity is becoming the fastest growing segment in the question of “what fuel does a bus have?” Electric buses do not have an internal combustion engine in the traditional sense; They are powered by lithium titanate or lithium iron phosphate batteries. This radically changes the approach to maintenance: there is no oil, filters, exhaust system and complex transmissions.
The main advantage of electric buses is the absence of local emissions and low noise levels. Passengers feel the difference immediately: there is no characteristic vibration and smell of diesel fuel during startup. The engine operates almost silently, providing smooth acceleration without jerking, which is especially important for people with limited mobility and elderly passengers.
However, electrification also has a downside. The enormous weight of the batteries (which can reach several tons) reduces passenger capacity or requires strengthening of the chassis. In addition, infrastructure is critical: electric buses require either overnight charging at a depot or rapid recharging at final stops via pantographs (Opportunity Charging technology).
- 🔋 Zero CO2 emissions and harmful impurities.
- 🔇 No noise and vibrations in the cabin and on the street.
- 📉 Reduced engine maintenance costs.
- ⏳ Limited range and dependence on charging infrastructure.
In winter, the range of an electric bus can drop by 30-40% due to the operation of the interior heater, which requires schedule adjustments and more frequent recharging.
Hydrogen fuel cells: the energy of the future
Hydrogen is often called the fuel of the future, and this is especially true for public transport. Hydrogen-powered buses (FCEVs) do not burn hydrogen, but instead use it in fuel cells to generate electricity, which then powers electric motors. The only product of the reaction is clean water dripping from the exhaust pipe.
The main advantage of hydrogen technology over batteries is its filling speed and range. You can fill a bus with hydrogen in 10-15 minutes, which is comparable to diesel, and it can travel long distances without recharging. This makes hydrogen promising not only for urban routes, but also for intercity routes, where the weight of batteries would be a critical limitation.
However, widespread adoption is hampered by the high cost of the fuel itself and the lack of infrastructure. Producing green hydrogen (produced using renewable energy) is still expensive, and transporting and storing hydrogen requires special conditions due to its high volatility and flammability.
Comparative analysis: fuel characteristics table
To systematize information about what kind of fuel does the bus have? is optimal in different conditions, consider a comparative table of the main parameters. It will help understand why cities choose one option over another depending on budget and environmental requirements.
| Parameter | Diesel | Methane (CNG) | Electricity | Hydrogen |
|---|---|---|---|---|
| Cost per km | High | Low | Average | Very high |
| Environmental friendliness | Low | Average | High | Maximum |
| Power reserve | 600+ km | 300-400 km | 150-300 km | 400+ km |
| Filling/charging time | 10 min | 15 min | 4-6 hours (night) | 15 min |
| Engine life | 1 million km | 1 million km | 2 million km (motor-wheel) | 30 thousand hours (cells) |
☑️ Criteria for choosing fuel for a fleet
Development prospects and hybrid technologies
The world does not stand still, and the answer to the question “what fuel does the bus have” may include several options at once. Hybrid buses, which combine a small diesel engine and an electric motor, save fuel in traffic jams and recover energy when braking. Such cars often do not require external charging, since the battery is charged by the engine and braking.
In the future, we may see the dominance of electricity in city centers and the use of hydrogen or biodiesel for long-haul flights. Biofuels made from agricultural waste are also being seen as a way to make existing diesel fleets greener without replacing engines.
The introduction of new technologies requires not only financial investments, but also the restructuring of the entire supply chain. Engineers face complex challenges in thermally regulating batteries, improving fuel cell efficiency, and creating safe energy storage systems.
⚠️ Attention: When a vehicle fleet switches to a new type of fuel, retraining of technical personnel is required, as the principles of diagnostics and repair change radically.
Is it possible to convert a diesel bus to gas?
Yes, there are certified systems for conversion (4th and 5th generation gas equipment). However, for buses this is a complex process, requiring the installation of heavy cylinders on the roof, reconfiguration of the engine electronics (ECU) and registration of changes with the traffic police. It is often more economically feasible to buy a new gas bus than to refurbish an old diesel one.
Why aren't electric buses used in winter?
Electric buses are used in winter, but their efficiency decreases. The main problem is the energy-intensive interior heating, which quickly drains the batteries. To solve this problem, heat pumps and pre-heaters are used, operating from the network during parking at the depot.
What is the cheapest fuel for a bus?
At the moment, the cheapest gas per kilometer is compressed natural gas (methane). However, when calculating your total cost of ownership (TCO), you must take into account the higher initial price of gas appliances and the cost of maintaining gas cylinders.
Is hydrogen dangerous for passengers?
Subject to production and storage technologies, hydrogen is no more dangerous than other types of fuel. It is lighter than air and, when leaked, instantly evaporates upward, without forming explosive clouds near the ground, unlike propane or gasoline vapors. Hydrogen bus tanks undergo bulletproof tests.