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Low Carbon Vehicles – Hybrids, Hydrogen, and Biofuels

October 25, 2023

What are Hybrid Vehicles?

Hybrid vehicles combine electric motors with internal combustion engines, using fossil fuels like petrol or diesel alongside batteries to drive the powertrain. 

Hybrid Vehicles

Hybrids: Comparing the emissions

Unlike EVs, hybrids still produce exhaust emissions, due to their use of internal combustion engines (ICE). While their total carbon output is significantly less than petrol/diesel vehicles (by around 45%), they still produce almost 50% more carbon than fully-electric vehicles.*

How do hybrid vehicles work?

Hybrids run on petrol or diesel in combination with battery power. You fill them up with fuel just as you would an ICE vehicle. Some hybrids also come with a plug to charge the battery, like an EV, while others derive their charge from the internal combustion engine, or features like regenerative braking.

What are the benefits of hybrid vehicles?

Hybrid vehicles have a much lower carbon footprint than pure petrol/diesel vehicles, making them an effective choice for environmentally-conscious drivers. Because they still use fossil fuels, hybrids don’t rely solely on charging infrastructure, often making them a more practical choice than fully-electric vehicles.

What are the challenges?

Switching to a hybrid vehicle is still a significant transition to make, and brings many of the same challenges as with EVs – especially where repairs are concerned. The high voltage power trains found in hybrids require specialist attention, tools, and safety equipment for their repair.

Plug-in hybrids rely on the availability of charging infrastructure, which is a vital consideration for drivers who may not be able to accommodate at-home charging.

*MIT Climate Portal, 2022

What are Hydrogen (HFC) vehicles?

Hydrogen vehicles use fuel cells to convert compressed hydrogen gas into electricity, which is used to power the electric motors that drive the wheels.

Contrary to popular misconception, hydrogen cars don’t actually burn gas for power. Instead, they rely on a chemical reaction to generate an electric current, which is fed through a battery, and into the motor which powers the wheels.

Hydrogen Fuel Cell Vehicles HFC

Hydrogen Vehicles: Comparing the emissions

Much like EVs, hydrogen vehicles don’t produce any exhaust emissions – aside from pure water vapour. This makes them effectively carbon neutral in day-to-day use, although some carbon is still produced through tire wear, brake discs, and vehicle production.

Hydrogen vehicles can even be more environmentally friendly than battery-electric vehicles (BEVs). Unlike BEVs, they don’t need to be recharged from the main power grid – which still relies on fossil fuels in the majority of regions.

How do hydrogen vehicles work?

Much like the name suggests, hydrogen fuel cell vehicles use pressurized gas – which is stored in an onboard tank, much like the fuel in petrol/diesel vehicles.

This means they’re currently quicker to refuel than EVs, taking only a few minutes to achieve a full tank. There’s also no need for charging infrastructure, as they don’t rely on mains power to charge the battery.

What are the benefits of hydrogen vehicles?

Hydrogen vehicles have a number of advantages over EVs and hybrids. They’re quicker to refuel than plug-in vehicles, often have a longer range, and don’t rely on mains electricity for power – meaning they’re more environmentally friendly.

What are the challenges?

The uptake of hydrogen vehicles has been stunted by the lack of public fuelling infrastructure, as well as the expensive nature of the gas they need for fuel.

There are currently just 15 hydrogen refuelling stations in the UK, making vehicles incredibly difficult to operate without investing in their own fuel storage and infrastructure.

Hydrogen vehicles are also less efficient than EVs. Their fuel cells have an energy efficiency rating of around 60%, compared to the near 100% efficiency of the lithium ion batteries found in EVs.

What are Biofuel vehicles?

Biofuel vehicles use naturally-derived fuels, usually made from food waste, cooking oils, or plant matter. Some biofuels are used as additives alongside petrol or diesel, and others can replace fossil fuels entirely.

One of the most common biofuels is biodiesel, which is often used to power large commercial vehicles like lorries and buses.

What are the different types of biofuels?

There are a number of different types of biofuels on the market, including but not limited to:

  • Biodiesels (including vegetable oil fuels)
  • Ethanol & other alcohols (including methanol and butanol)
  • Biogas (like methane derived from food waste)
  • Biogasoline (and other renewable hydrocarbon fuels)
Biofuels like biodiesel

Biofuels: Comparing the emissions

The emissions generated by biofuel depend on which fuel you’re using, and whether you’re using it independently, or alongside fossil fuels.

Biodiesel (B100) produces 74% fewer carbon emissions* than petroleum diesel throughout its lifecycle – including extraction, transportation, and use in vehicles.

However, biodiesel isn’t without its own emissions challenges. While it’s responsible for far fewer carbon emissions, it does emit other gases like aldehydes and nitrogen oxides.

There’s also the issue of its production, which can be energy intensive, and therefore accounts for high use of grid energy – which is often reliant on fossil fuels.

How do biofuel vehicles work?

Biofuel vehicles use naturally-derived fuels – usually made from biomass like plant matter or food waste. These fuels are used to power an internal combustion engine, just like the kind you’d find in a petrol or diesel vehicle.

They’re usually refuelled just like petrol/diesel cars – using an onboard tank to store the fuel, and pumps to deliver it to the engine.

Biofuels aren’t commonly found at filling stations, and have to be ordered directly from the supplier, meaning you’ll need to store it yourself.

What are the benefits of biofuels?

Biofuels, whether used independently or as an additive, can be an effective way to cut vehicle carbon emissions – especially in large commercial vehicles, like HGVs and plant equipment.

For companies operating fleets, switching to biofuels provides an easier way to harness low-carbon vehicles without the challenges presented by EVs, such as their reduced range, and the need to recharge.

What are the challenges?

Biofuels can be a challenge to source. They aren’t commonly available at filling stations, and usually need to be ordered/delivered directly from the supplier.

Fuels like Biodiesel can also be more expensive per gallon than their fossil fuel counterparts, due to the expense associated with their production.

They’re also not usually as efficient as fossil fuels, which means vehicles using biofuels may be less powerful, and could see fewer miles per gallon when they’re used independently. However, using biofuels as additives to fossil fuels can help to increase efficiency, while reducing carbon emissions.

*The Alternative Fuels Data Center

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