Tom Melhuish 4 min read

Turning coffee grounds into Biofuel

Coffee is, without a doubt, the drink of choice for most people of working age in the UK, with national consumption exceeding 95 million cups every day.

This produces a quarter of a million tonnes of wet Spent Coffee Grounds (SCG), most of which end up in landfills, emitting methane gas which is many times more potent than carbon dioxide.

So how can coffee culture turn into a solution to reduce fossil fuel consumption?

Key takeaways

  • Spent coffee grounds contain 10-20% oil, making them a potential source of efficient biofuel through a process called transesterification, which separates the oils from the coffee mass.
  • Biofuel made from spent coffee grounds can be mixed with diesel or gasoline for vehicle use, as demonstrated by London’s double-decker buses powered by B20 biofuel.
  • Using spent coffee grounds as a biofuel offers environmental benefits like reducing landfill waste and carbon emissions, which could have a big impact on the food and beverage sector.

What is a biofuel?

This is simply a liquid or gaseous fuel which is extracted from biomass. If you want the details, here’s a full guide on biofuels.

How can coffee be used as fuel?

Before you start trying to turn your morning coffee waste into your car’s petrol as part of your weekend DIY project, let’s look at what the research indicates.

Coffee beans are actually seeds and, as such, are full of oils and fats. If you look closely at your morning cuppa, you may notice an oily substance floating on the surface, extracted while brewing.

However, most of this oil remains in Spent Ground Coffee (SCG), which is made of around 10-20% oil and can potentially be an efficient biofuel.

How do you turn spent coffee grounds (SCG) into biofuel?

Without getting too technical, the process involves ‘transesterification’, which removes the oils from the coffee mass using a variety of chemicals to separate it.

Once separated, this oil can be mixed with diesel or gasoline to produce a fuel for vehicles.

For example, B20 biofuel, produced by mixing gasoline with oils extracted from London’s spent ground coffee, powers the large fleet of iconic double-decker buses.

Despite emitting carbon, this reduces the reliance on fossil fuels.

What are the advantages and disadvantages of using coffee waste as a biofuel?

Advantages

  • Reducing carbon emissions by removing coffee ground waste from general business waste disposal.
  • Reduction in the use of crop-derived biofuels like palm, sugarcane and corn oil, which have a questionable environmental reputation.
  • High-quality oil may be used to power vehicles.
  • Requires less filtering than other oils like spent cooking oil.
  • There is a renewable source of coffee waste, which is unlikely to stop.
  • Reducing the required volumes of commercial waste collections and their associated costs.

Disadvantages

  • Spent Coffee Ground oils cannot be used as biofuels alone as infrastructure is often designed for diesel and petrol.
  • Relies on coffee consumption. If this stops for any reason, the entire industry will collapse.
  • Re-processing the spent coffee grounds removes their potential as plant nutrients, disrupting the carbon cycle.
  • Even if renewable, burning spent coffee biofuel still emits greenhouse gasses.

Is using coffee grounds as a biofuel classed as green energy?

Green energy refers to the generation of energy from sources that are renewable in a human timescale, and spent coffee grounds certainly fall within this range. Given current consumption rates, coffee grounds are an extremely resilient source of green energy.

A study by the University of Loughborough (using spent coffee from their cafe) suggests that the spent coffee generated annually in the UK has the potential to replace 4.4% of the coal used for electricity generation in the country.

What else can you do with spent Coffee Grounds?

Apart from biofuel, the coffee waste may be used for a multitude of applications such as biomass, bioplastics and compost. The leading company innovating this space appears to be a UK-based bio-bean.

Biomass:

The remaining fibres from the coffee grounds are extremely calorific and, if processed appropriately, can be turned into coffee logs or coffee pellets for heating applications.

These are available all over the UK and have been quoted as burning 20% hotter and longer than kiln-dried wood while saving about 80% carbon emissions compared to sending the coffee waste to landfills.

Also, being sustainable biomass products, these are exempt from the recent UK ban on coal and wood from domestic heaters.

Upcycling:

Virtually anything can be made from spent coffee grounds, and research keeps finding more uses. The carbon can be manipulated to make bioplastics and sterile coffee grounds can be turned into skin scrubs or to increase friction in brake pads.

It is only a matter of time until these become properly scalable.

Compost:

Spent Coffee grounds may also be used as fertilizer in commercial food waste recycling.

 

Using coffee grounds as a biofuel – FAQs

Are coffee grounds classed as a biofuel?

Coffee ground waste is unusable as a biofuel in its spent state and needs further processing to extract its liquid oils (remember, biofuels must be a liquid or gas!)

The coffee ground can also be upcycled into useful materials like bioplastics, and the remaining fibres can be used to create coffee logs, which may be categorised as a source of biomass energy.

Realistically, how sustainable is it to use coffee waste as a way to power vehicles?

This is not a question of whether it’s possible but how much the re-using process can scale.

As mentioned earlier, the fleet of double-decker London buses has already been powered by a B20 biofuel since 2017. 20% of this biofuel comes from Spent Coffee Ground oils.

Can I heat my business using spent coffee grounds?

You can certainly use coffee logs made of spent coffee grounds to heat your business if you have a kiln or wood/coal burner.

However, the reality is that most buildings in the UK use gas heating systems, and infrastructure is difficult to replace from one day to another.

We understand that with the current business gas prices everyone is looking to save on heating costs, especially as winter is coming.

 

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