NOVELTY - A computerized method (M1) of using a data processor with a memory to account for carbon flows and determine regulatory value for biofuel involves: storing, in memory, two set of value characterizing carbon flows associated with production and use of biofuel derived from a first fraction of agricultural biomass, and with the sequestration of solid phase biomass carbon derived from second fraction of the agricultural biomass and where the sequestration mitigates anthropogenic greenhouse gas emission respectively; and calculating regulatory value using a data processor from two sets.    USE - For using a data processor with a memory to account for carbon flows and determine regulatory value for biofuel; for engineering carbon cycle for biofuel production and use (all claimed); for sequestering solid phase carbon in biomass away from the atmosphere for time periods appropriate for mitigating anthropogenic greenhouse gas emissions.    ADVANTAGE - The method assess a variety of social and environmental performance characteristics of biofuels. The method enables realization of environmental benefits associated with the reduction of greenhouse gas emissions in biofuel carbon cycles e.g. it mitigates anthropogenic greenhouse gas (GHG) emissions by providing biofuels that have a lower carbon intensity than conventional biofuels or conventional fossil hydrocarbon fuels. Additionally, solid phase biomass carbon storage (SPBCS) operates within the context of various regulatory systems, enabling the environmental benefits to be quantified and associated with a biofuel or a tradable credit. Thus, SPBCS can also help provide an economic incentive for providing environmental benefits; represents a unique alternative and an advance when compared to other approaches to mitigating anthropogenic greenhouse gas emission, including production of low carbon fuels and carbon sequestration e.g. carbon capture and storage (CCS) represents a set of technologies capable of concentrating, compressing, transporting (as necessary), and sequestering CO2 (e.g. from industrial processes) away from the atmosphere (e.g. in geologic formations). The direct association enables crediting emissions and other sustainability benefits resulting from the sequestered biomass carbon to the biofuel produced, yielding biofuel products with reduced carbon intensity and/or improved performance against sustainability measures. The SPBCS has the advantage that the stored carbon can be removed from storage and repurposed e.g. when it can be used in products or services that continue to prevent atmospheric releases of stored carbon (e.g. building materials or energy systems with CCS), that otherwise continue to provide climate benefits, when development of other technologies lessens the climate risks associated with atmospheric release of stored carbon (e.g. capture of CO2 directly from the atmosphere), or when climate risks are determined to have been otherwise resolved.    DETAILED DESCRIPTION - A computerized method (M1) of using a data processor having a memory to account for carbon flows and determine a regulatory value for a biofuel involves: storing, in memory, a first set of at least one value characterizing carbon flows associated with the production and use of a biofuel, where the biofuel is derived from a first fraction of an agricultural biomass; storing, in memory, a second set of at least one value characterizing carbon flows associated with the sequestration of solid phase biomass carbon, where the solid phase biomass carbon is derived from a second fraction of the agricultural biomass and where the sequestration mitigates anthropogenic greenhouse gas emission; and calculating, using the data processor, a regulatory value for the biofuel from the first and second sets of carbon flow values. INDEPENDENT CLAIMS are included for the following:    (1) engineering (M2) a carbon cycle for biofuel production and use involving: arranging the production of a biofuel from a first fraction of an agricultural biomass and the sequestration of solid phase biomass carbon from a second fraction of the agricultural biomass, thus mitigating anthropogenic greenhouse gas emission; and assigning a regulatory value to the biofuel from a first set of at least one carbon intensity value characterizing the production and use of the biofuel, and a second set of at least one carbon intensity value characterizing the sequestration; and    (2) manufacturing (M3) a biofuel involving: producing a biofuel from a first fraction of an agricultural biomass; sequestering solid phase biomass carbon from a second fraction of the agricultural biomass, where sequestration mitigates anthropogenic greenhouse gas emission; and assigning the biofuel a regulatory value based upon a first set of at least one carbon intensity values characterizing the production and use of the biofuel and a second set of at least one carbon intensity value characterizing the sequestration.