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?
What is a biofuel?
This is simply a liquid or gaseous fuel which is extracted from biomass. If you want the details, we have our own brief 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 a seed, 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, which is extracted while brewing.
However, most of this oil remains in Spent Ground Coffee (SCG), which is made of around 10-20% oil and has the potential for being an efficient biofuel.
How do you turn spent coffee grounds (SCG) into biofuel?
Without getting too technical, the process involves a process called ‘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 that vehicles may use.
For example, B20 biofuel produced from mixing gasoline with oils extracted from London’s spend ground coffee is used to power the large fleet of London’s 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?
- Reducing carbon emissions by removing coffee ground waste from municipal landfills.
- 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.
- Spent Coffee Ground oils cannot be used as biofuels on their own as infrastructure is often designed for diesel and petrol.
- Relies on coffee consumption. If this stops for any reason, the entire industry would 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 which are renewable in a human timescale, and spent coffee grounds certainly fall within this range.
At AquaSwitch we go as far as to argue that coffee grounds are an extremely resilient source of green energy, given current consumption rates.
A study by the University of Loughborough (using the spent coffee from their cafe) suggests that the spent coffee generated annually in the UK has the potential of replacing 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 UK-based bio-bean.
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.
Virtually anything can be made from spent coffee grounds, and research keeps finding more uses. The carbon can be manipulated to make bioplastics, 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.
Spent Coffee grounds may also be used as fertilizer if composted appropriately and are used in many households to nurture their gardens and vegetable plots.
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 if it’s possible, but of how much the re-using process can scale.
As mentioned earlier, the fleet of double-decker London buses is already being 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 ground?
You can certainly use coffee logs made of spent coffee ground to heat your business if you have a kiln or wood/coal burner.
However, the reality is that the vast majority of 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.
At AquaSwitch we have built a business gas comparison to help you get the best prices possible given the difficult circumstances businesses are facing in 2022.