NOVELTY - Gasifying (M1) feedstock involves: filling a gasifier with feedstock, where the gasifier comprises several conjoined and vertically positioned tubes having an interior/exterior wall, proximal/distal end, where the proximal end provides inlet, and distal end provides an outlet, pyrolysis zone, oxidation zone and reduction zone; igniting feedstock; injecting oxidant streams into the oxidation zone using two rings of plano air inlets; moving feedstock sequentially through the pyrolysis zone; holding feedstock and a bed of biochar inside the gasifier; removing and refilling steps.    USE - For gasification of feedstock (claimed) which used for gasifying solid biomass, household and industrial waste, fossil fuels as well as other carbon-containing feedstock using downdraft gasification.    ADVANTAGE - The shape of the tubes eliminates the need for a restriction (hearth) in the gasifier, which limits the maximum achievable throughput. The rotating and vertically adjustable grate is located beneath, but not attached to, the reduction zone of the gasifier. The method provides downdraft gasifier design that allows the flow rate of feedstock to be controlled as it passes through the oxidation zone with minimal restriction to improve the overall volume and flow of feedstock passing through the gasifier.    DETAILED DESCRIPTION - Gasifying (M1) feedstock involves: filling a gasifier with feedstock, where the gasifier comprises several conjoined and vertically positioned tubes having an interior wall, exterior wall, proximal end and distal end, where the proximal end provides an inlet and the distal end provides an outlet, pyrolysis zone, oxidation zone and reduction zone; igniting the feedstock to create an oxidation band; injecting oxidant streams into the oxidation zone using at least two rings of plano air inlets; moving feedstock sequentially through the pyrolysis zone where the feedstock begins to fluidize and decompose, then an oxidation zone where the feedstock changes to producer gas and then a reduction zone where the producer gas mixes with biochar to cool and form additional producer gas; holding feedstock and a bed of biochar inside the gasifier using a rotating and vertically adjustable grate positioned below the reduction zone; removing biochar and producer gas through a bypass and holes in the grate; and refilling the gasifier with feedstock.