Recycling Coffee Grounds into Biomass Pellets for Home Heating

General Information of Coffee Grounds Pelleting
That coffee has the function of refreshing spirit and bringing life benefits is known by almost everyone, while its role of low-carbon and environmental combustion material is beyond people’s knowledge. Proved by related experiments, the oil extracted from spent coffee grounds can be further processed into bio-diesel, and their leftovers can be pelleted into solid biomass fuel which possesses higher heat value over those made from wood and agricultural wastes.
The yearly coffee production is about 8 million in the world, resulting in large amounts of residues during the brewing process. Different from the whole procedure of crushing, drying, pelletizing, cooling and packing for other feedstock, coffee grounds pelleting is much easier and far more convenient to be completed in virtue of their own features and properties.

Composition Feasibility of Coffee Grounds Pelletizing

Item	Parameter	Item	Parameter
Total carbon(%)	52.2	Ash(%)	1.43
Total lignin(%)	33.6	Heat value(MJ/kg)	4619.2

1.Moisture: For most other raw materials, a wood dryer must be adopted because biomass wood pellet machine line has a strict requirement for their water content, about 10%-15%, yet for the production of coffee residue biomass pellets, no such equipment is needed. Its 12.2% of moisture is right within the standard range.
2.Carbon: Generally speaking, more carbon content equals to better combustion feature and higher heat value. 52.2% of coffee residues takes up the top place among various kinds of feedstock for biomass wood pellet machine.
3.Ash: Different from forestry residues and agricultural wastes, the former got from furniture factory, paper plant and sawmill and the latter from crop harvesting, raw materials for coffee grounds pelleting is obtained in the making process of food which has been well cleaned and inspected.
4.Lignin: Lignin plays the role of additive during coffee grounds pelleting. Without any such substances, produced biomass pellet fuel may be hard to mold and easy to break.
5.Heat value: The heat value of spent coffee grounds reaches as high as 4619.2 MJ/kg, making them more ideal for producing pellet biomass fuel.

Production Process and Machines Needed for Coffee Grounds Pelleting

1.Pelletizing process: What’s needed here is biomass wood pellet machine whose main components are pelletizing chamber, die and rollers, respectively playing the role of changing the structure of raw materials, discharging re-structured materials through die hole and thus changing them into pellet shape, driving the die rotating and supplying required force during pelletizing process.
Spent coffee grounds are fed into pellet mill chamber and sent into the space between rollers and die under the rotating strength of rollers. After enough pressing force of die and rollers on materials and friction between die and materials as well as materials and rollers, they’re squeezed out as coffee residue biomass pellets with designed size.
2.Cooling process: Generally, counter flow pellet cooler is adopted in case that high-temperature coffee residue biomass pellets should lead to the damage of quality and the malfunction of packing machine. The reason why it’s called counter flow cooler is because of the opposite direction of materials and air feeding, the former from top to bottom while the latter from bottom to top, which prevents surface cracking of pellets and ensures its thorough cooling effect.
3.Packing process: After being pelletized and cooled, produced coffee residue biomass pellets should be properly packed in order to make the subsequent storage and delivery more convenient. For this process, the automatic filling, conveying and sealing design of our vacuum pellet packing machine enables you to do nothing after putting bags in appropriate place.

Advantages of Coffee Grounds Pelleting Compared with Other Biomass Pellet Fuel Production
1.Higher heat value of produced pellets: There are 52.2 kg of carbons in every 100 kg of spent coffee grounds, which contributes to the high heat value of coffee residue biomass pellets produced from them, reaching about 4630 MJ/kg. In comparison, the 4500-4600 MJ/kg of wood sawdust pellets and 4200-4300 MJ/kg of agricultural waste pellets are a little lower.
2.Lower cost of materials and machines: The cost talked about here regards to not only investment on raw materials but also expense on required machines. On one hand, coffee residues are something that individuals, shops and factories need to either throw away or take to garbage recollecting station. Whether way disposed of, these are wastes in their eyes and those who help fetch them will be welcomed and thanked. On the other hand, neither biomass crusher nor dryer is needed for coffee grounds pelleting thanks to their composition feature and size property, which saves expenses on these two machines accordingly.
3.Cleaner property of feedstock: Unlike forestry residues and agricultural wastes which are obtained from cropland, furniture factory, paper plant or sawmill, this feedstock is the leftover of coffee making. As something to eat, the raw materials, coffee bean, must have been pre-processed so that both the finished product and byproduct are clean and have no harm to human body.
4.Short growing period of raw materials: The growing period of trees is about 4 years compared with which the half a year to a year of coffee beans is much shorter. That means you’ve produced pellet biomass fuel and made profits from spent coffee grounds for 4-8 years before the trees where forestry residues come from grow up.
FAQ About Coffee Grounds Pelleting
1.Why to make coffee residue biomass pellets?
First, the problem of energy shortage is more and more vigorous, so development and production of pellet biomass fuel have become a way out. Second, throwing away of spent coffee grounds will bring decontamination burden for environment. Third, coffee residues used as fertilizer are harmful for soil due to the caffeine, tannins and polyphenols in them.
2.Can profits be made from coffee grounds pelleting?
On one hand, the cost of coffee residues is lower than other raw materials. On the other hand, reasonable design of biomass wood pellet machine, pellet cooler and packing equipment reduces the amount of labor force and energy consumption. The two factors together enable you to get investment back only in a few months after which profits can be gladly made and enjoyed.
3.Is crushing process needed for coffee grounds pelleting?
In order to prevent clogging during pelletizing process, biomass wood pellet machine requires the size of its feedstock to be less than 5 mm which spent coffee residues can achieve without any doubt. Therefore, crushing process can be saved here.
4.Is drying process needed for coffee grounds pelleting?
Many raw materials should be dried before being sent to biomass wood pellet machine, while this situation doesn’t apply here because the water content of spent coffee grounds is about 12.2% which is in the range of its moisture requirement, 10%-15%.
5.Is extra additive needed for coffee grounds pelleting?
We know lignin contained in wood materials (such as sawdust, branch, and bark) can play the role of additive so that no investment needed for this part of necessity. Similarly and luckily, in coffee grounds also exist such substance whose proportion is as high as 33.6% in total.
6.What’s the use of produced coffee residue biomass pellets?
Like other pellet biomass fuel, the application of coffee residue biomass pellets ranges from industrial field to household living. In the former case, they act as the fuel of mass production in paper mill, chemical plant, power station, fertilizer factory, etc. In the latter, it embodies daily heat supply for individual family or service industry including restaurant, hotel and bank.