NOVELTY - Producing biofuel, involves fractionating the photosynthetically-produced biological material into at least two fractions, where a first fraction enriched in the biofuel precursor and a second fraction enriched in the cell-wall component, processing one or more of the second fraction and a product of its modification to generate thermal energy, and processing at least one of the first fraction, a product if its modification, and a component of the first fraction to generate biofuel.    USE - For producing biofuel. The biofuel is chosen from ethanol, biodiesel, fatty acid methyl esters, products of pyrolysis and bio-hydrogen, preferably biodiesel, fatty acid methyl esters, biohydrogen and products of pyrolysis (claimed).    ADVANTAGE - The method minimizes the consumption of fossil fuel in producing biofuels and is eco-friendly.    DETAILED DESCRIPTION - Producing biofuel (52), involves (a) providing a renewable (22), photosynthetically-produced biological material comprising one or more biofuel precursor and a cell-wall component, fractionating the photosynthetically-produced biological material into at least two fractions, a first fraction enriched in the biofuel precursor and a second fraction enriched in the cell-wall component, processing at least one of the second fraction and a product of its modification to generate thermal energy (42), and processing at least one of the first fraction, a product if its modification, and a component of the first fraction to generate at least one biofuel, where processing includes at least one energy-consuming operation that consumes energy resulting from processing step, (b) providing a starch crop comprising starch and fiber, fractionating the starch crop into at least two fractions, a first fraction enriched in starch and a second fraction enriched in fiber, processing at least one of the second fraction and its product to generate thermal energy, processing at least one of the first fraction, its component and product to generate biofuel, where processing includes at least one energy-consuming operation and where the operation consumes energy resulting from the processing step, (c) providing an oilseed crop comprising oil and fiber, fractionating the oilseed crop into at least two fractions, a first fraction enriched in oil and a second fraction enriched in fiber, processing at least one of the second fraction and a product thereof to generate thermal energy, processing at least one of the first fraction, a component thereof and a product thereof to generate biofuel, where the processing step comprises at least one energy- consuming operation and where the operation consumes energy resulting from the processing step, or (d) providing an algal material comprising at least one biofuel precursor (32) and a cell-wall component, fractionating the algal material into at least two fractions, a first fraction enriched in the precursor and a second fraction enriched in the cell-wall material, processing at least one of the second fraction and a product thereof to generate thermal energy, processing at least one of the first fraction, a component thereof and a product thereof into at least one biofuel, where the processing step comprises at least one energy- consuming operation and where the operation consumes energy resulting from processing step.    DESCRIPTION OF DRAWING(S) - The figure is a flow chart representing the biofuel production.    Renewable biological material (22)    Biofuel precursor (32)    Cellulose or hemicellulose (34)    Thermal energy (42)    Biofuel (52)