by bubbling it through a pond in which algae are grown the heat generated during the optional regeneration step may be used to supply the heat for the endothermic reaction of step b to this end hot catalyst particles from the regenerator are recycled to step a or b of the process the amount of coke deposit may be such that the amount of heat generated during the regeneration step may be greater than what is need for fueling the conversion reaction if this is the case excess heat may be removed from the process by cooling the catalyst particles to a desired temperature prior to recycling them into the reactor the desired temperature is determined by the heat balance for the process and the desired reaction temperature for step b accordingly the desired temperature of the catalyst particles just prior to recycle may be determined in a manner similar to that used in fcc processes if heat is removed from the regenerated catalyst particles this heat may be used for generating steam hot water or electricity in a preferred embodiment the process is carried out in an fcc unit it may be desirable to carry out step a in a pretreatment reactor prior.