Energy from waste coffee

Activated carbon derived from waste coffee grounds for stable methane storage (2015):

"An activated carbon material derived from waste coffee grounds is shown to be an effective and stable medium for methane storage. The sample activated at 900 °C displays a surface area of 1040.3 m2 g−1 and a micropore volume of 0.574 cm3 g−1 and exhibits a stable CH4 adsorption capacity of ~4.2 mmol g−1 at 3.0 MPa and a temperature range of 298 ± 10 K. The same material exhibits an impressive hydrogen storage capacity of 1.75 wt% as well at 77 K and 100 kPa. Here, we also propose a mechanism for the formation of activated carbon from spent coffee grounds. At low temperatures, the material has two distinct types with low and high surface areas; however, activation at elevated temperatures drives off the low surface area carbon, leaving behind the porous high surface area activated carbon."

Waste Coffee Grounds as an Energy Feedstock (2011):

"The aim of this study was to demonstrate the utilization of waste coffee grounds as a potential new-low cost alternative feedstock for biodiesel production.(...) spent coffee grounds were collected from local coffee houses. The grounds were dried in an oven at 105° C to remove moisture (mostly 25 wt%) and then the oil was extracted by applying a soxhlet process. A low-boiling organic solvent such as n-hexane was used. Afterwards the oil was separated from the solvent using a rotary evaporator and its physicochemical properties were measured. The experimental results showed that the oil content of spent coffee grounds is between 10-15 % w/w (on a dry weight basis). The oil was converted to biodiesel via transesterification reaction. All the reactions were carried out at 65oC for 2 h with anhydrous methanol in methanol-to-oil molar ratio, 9:1using sodium hydroxide (NaOH) as catalyst in amount (1%). The conversion of coffee oil was found to be about 92 %. Finally, the quality parameters of the produced biodiesel were determined according to the European standard EN 14214. (...) In addition, the waste solid remaining after the oil extraction can be utilized as compost as well as fuel pellets. This work could offer a new perspective in the production of biofuels."