NOVELTY - A paddle operated biodiesel reactor comprises reactor vessel (a), stirrer (h), chain drive (d) and gear drive (c), where the reactor is mounted on a sturdy mild steel structure, and is adapted to stir raw materials required for biodiesel production using transesterification.    USE - As paddle operated biodiesel reactor for biodiesel production (claimed).    ADVANTAGE - The reactor needs only manual paddling for stirring the raw materials required for biodiesel production. The chain drive and gear drive provided in between the paddle and the stirrer, which increases the speed of rotation of the stirrer; and also reduces the speed of rotation of the paddling. The chain drive and gear drive makes the paddling easy and the operator does not have much strain; and also it provides exercise for the operator. The device is compact and needs less space; does not need any electrical energy for both heating and stirring, is user friendly and does not need skilled labor for operation. The manually operated, portable and paddle operated biodiesel reactor needs less maintenance. The device is a paddle operated (instead of an electric motor) and needs less investment and the operating cost is negligible. By using the device, biodiesel can be produced from the reactants which are required for biodiesel production, without any electrical energy. Using the reactor, a refined and filtered vegetable oil having negligible water content can be converted into biodiesel by base or acid catalyst transesterification reaction and obtains a biodiesel yield of 75-90%. The device does not have any sophisticated parts and hence the cost of replacement of parts, servicing and maintenance of the reactor is negligible as compared to the automated biodiesel reactor; and allows production of biodiesel using sources of vegetable oils such as Sunflower, Gingelly, Honge, Jatropha; which is important in rural and remote areas.    DETAILED DESCRIPTION - A paddle operated biodiesel reactor comprises reactor vessel (a), stirrer (h), chain drive (d) and gear drive (c), where the reactor is mounted on a sturdy mild steel structure, and is adapted to stir raw materials required for biodiesel production, using transesterification. The raw materials required for biodiesel production are in the form of liquids. In the reactor, two sets of blades are used for better mixing of reactants, where height of adjustable blade set can be varied depends upon level of reactants in vessel, and biomass available in the agricultural waste or combustible waste can be burnt to heat reactants. The stirrer blade is made of stainless steel.    DESCRIPTION OF DRAWING(S) - The figure shows a view of the portable paddle operated zero electrical energy biodiesel reactors.    Reactor vessel (a)    Biomass stove (b)    Gear drive (c)    Chain drive (d)    Grate (e)    Thermometer (f)    Feeding valve (g)    Stirrer (h)    Level indicator (i)    Paddel (j)    Frame (k)    Seat (l)    Handle bar (m)    Guard (n)