A sustainable energy system includes energy efficiency, energy reliability, energy flexibility, fuel poverty, and environmental impacts. A sustainable biofuel has two favourable properties which are availability from renewable raw material, and its lower negative environmental impact than that of fossil fuels. Charcoal is produced by slow heating wood (carbonization) in airtight ovens or retorts, in chambers with various gases, or in kilns supplied with limited and controlled amounts of air. The charcoal yield decreased gradually from 42.6 to 30.7% for the hazelnut shell and from 35.6 to 22.7% for the beech wood with an increase of temperature from 550 to 1,150 K while the charcoal yield from the lignin content decreased sharply from 42.5 to 21.7% until it was at 850 K during the carbonization procedures. The charcoal yield decreases as the temperature increases. The charcoal briquettes that are sold on the commercial market are typically made from a binder and filler.