TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The biogas converter includes a refrigeration cycle, and where the thermal path is positioned to transmit a refrigerated substance from the biogas converter to the aquatic plant cultivator. The refrigerated substance includes dry ice and where the thermal path is positioned to transfer the dry ice to the aquatic plant cultivator. The portion of the thermal energy includes thermal energy produced by the refrigeration cycle. The thermal path includes a first portion connected between the biogas converter and the aquatic plant cultivator, and a second portion connected between the biogas converter and the anaerobic digester. The anaerobic digester is coupled to the aquatic plant cultivator to return anaerobic digester by-products to the aquatic plant cultivator. The system further comprises: an aquatic plant biomass path coupled between the aquatic plant cultivator and the anaerobic digester to direct an aquatic plant biomass to the anaerobic digester; an anaerobic digester return path coupled between the anaerobic digester and the aquatic plant cultivator to direct output from the anaerobic digester to the aquatic plant cultivator; and a biogas path coupled between the anaerobic digester and the biogas converter to direct biogas to the biogas converter, where the thermal path includes a first thermal return path coupled between the biogas converter and the anaerobic digester to direct a first thermal output from biogas converter to the anaerobic digester, and a second thermal return path coupled between the biogas converter and the aquatic plant cultivator to direct a second thermal output from biogas converter to the aquatic plant cultivator, and where the controller is coupled to the aquatic plant cultivator, the anaerobic digester and the biogas converter, and is programmed with instructions that, when executed, directs flow of constituents and energy among the aquatic plant cultivator, the anaerobic digester and the biogas converter. The anaerobic digester return path carries at least one of nutrients and water from the anaerobic digester to the aquatic plant cultivator. The system further comprises a municipal solid waste path coupled to the anaerobic digester to provide municipal solid waste to the anaerobic digester. The anaerobic digester includes: an anaerobic digester vessel; a holding vessel positioned to receive the municipal solid waste via the municipal solid waste path, and receive aquatic plants from the aquatic plant cultivator; a pre-processor positioned to receive a mixture of aquatic plants and municipal solid waste from the holding vessel, and control a moisture content of the mixture; a flow path coupled between the pre-processor and the anaerobic digester vessel to convey the mixture from the pre-processor to the anaerobic digester vessel; a first heat exchanger positioned to heat aquatic plants upstream of the holding vessel; a second heat exchanger positioned between the holding vessel and the pre-processor to cool the mixture entering the pre-processor; and a fluid flow path coupled between the pre-processor and the aquatic plant cultivator to transfer waste liquid from the pre-processor to the aquatic plant cultivator, where the fluid flow path passes through the second heat exchanger to cool the mixture entering the pre-processor, and passes through the first heat exchanger to heat the aquatic plants entering the holding vessel. The controller is programmed with instructions directing the: timing for transferring carbon dioxide from the biogas converter to the aquatic plant cultivator; physical conveyance of carbon dioxide from the biogas converter to the aquatic plant cultivator; and ransfer of waste heat from the biogas converter to the aquatic plant cultivator to heat the aquatic plant cultivator. The controller is operatively coupled to a carbon dioxide sensor at the aquatic plant cultivator, and the instructions include directing a transfer of carbon dioxide to the aquatic plant cultivator in response to a signal from the carbon dioxide sensor corresponding to a low carbon dioxide level. The controller is operatively coupled to a temperature sensor at the aquatic plant cultivator, and the instructions include directing a transfer of cold carbon dioxide to the aquatic plant cultivator in response to a signal from the temperature sensor corresponding to a high temperature. The cold carbon dioxide includes dry ice, and the thermal path includes a dry ice conveyance device. The anaerobic digester includes an anaerobic digestion vessel, and the thermal path is operatively coupled to the anaerobic digestion vessel to heat the aquatic plants and the MSW to a temperature suitable for anaerobic digestion. The anaerobic digester includes an anaerobic digestion vessel and a holding vessel coupled to the anaerobic digestion vessel to provide constituents to the anaerobic digestion vessel, and the thermal path is positioned to heat constituents that are at least one of (a) upstream of the holding vessel, (b) in the holding vessel, or (c) in the anaerobic digestion vessel. The biogas converter is further coupled to the anaerobic digester to provide electrical power to the anaerobic digester. The thermal energy includes waste heat from a refrigeration cycle at the biogas converter. The controller is programmed with instructions that direct the carbon dioxide to the aquatic plant cultivator in response to an indication of low carbon dioxide or high temperature at the aquatic plant cultivator. Preferred Method: The method-3 comprises: growing aquatic plants by receiving sunlight, recycled carbon dioxide, recycled water and recycled nutrients at an aquatic plant cultivator; receiving the aquatic plants and MSW at a pre-treatment device; directing recycled thermal energy to the pre-treatment device to kill the aquatic plants and kill pathogens carried by the aquatic plants and the MSW; directing the aquatic plants and the MSW from the pretreatment device to an anaerobic digester vessel; producing nutrients, water and biogas at the anaerobic digester vessel; recycling the nutrients and water by directing the nutrients and water to the aquatic plant cultivator; receiving the biogas at a biogas converter; liquefying methane from the biogas at the biogas converter; producing carbon dioxide from the biogas at the biogas converter; producing waste heat at the biogas converter as a result of liquefying the methane; recycling the carbon dioxide and controlling a temperature at the aquatic plant cultivator by directing the carbon dioxide to the aquatic plant cultivator; recycling a first portion of the waste heat by directing the first portion to the aquatic plant cultivator; and recycling a second portion of the waste heat by directing the second portion to at least one of the pre-treatment device and the anaerobic digester vessel. The method-1 further comprises: automatically monitoring a rate of aquatic plant production at the aquatic plant cultivator; automatically monitoring a rate of biogas production at the anaerobic digester; automatically monitoring a rate of liquid methane production at the biogas converter; automatically controlling a flow of energy and materials among the aquatic plant cultivator, where the anaerobic digester and the biogas converter are based at least in part on the rate of aquatic plant production, the rate of biogas production, and the rate of liquid methane production; directing aquatic plants from the aquatic plant cultivator into the holding vessel; directing MSW into the holding vessel; carrying a mixture of the aquatic plants and the MSW in the holding vessel at an elevated temperature to kill at least a portion of the aquatic plants and kill pathogens in the mixture; increasing a solids fraction of the mixture by removing liquid from the mixture at the pre-treatment device; directing the mixture to the anaerobic digester vessel; directing the liquid removed from the mixture through a first heat exchanger and a second heat exchanger; at the second heat exchanger, transferring heat from the removed liquid to the mixture entering the pre-treatment device; at the first heat exchanger, transferring heat from the removed liquid to the aquatic plants entering the storage vessel; returning at least a portion of the removed liquid to the aquatic plant cultivator; removing water and nutrients from the anaerobic digester vessel; transferring heat from the removed water and nutrients to aquatic plants entering the holding vessel; carrying the aquatic plants in the holding vessel at an elevated temperature to kill at least a portion of the aquatic plants; directing an aquatic plant-containing flow from the holding vessel to the pre-treatment device; removing fluid from an aquatic plant-containing flow at the pre-treatment device; pre-heating the aquatic plant-containing flow entering the pre-treatment device with removed fluid from the pretreatment device; pre-heating aquatic plants entering the holding vessel with removed fluid from the pre-treatment device; and directing the removed fluid to the aquatic plant cultivator. In the method, growing aquatic plants includes growing microalgae or duckweed. The step of transferring the portion of thermal energy includes transferring refrigeration energy to the aquatic plant cultivator. The step of transferring the portion of thermal energy includes transferring dry ice or cold liquid carbon dioxide to the aquatic plant cultivator, and transferring thermal energy that is not a direct result of combusting biogas or liquefied methane. The pre-treatment device includes a holding vessel and the directing thermal energy includes directing thermal energy to the aquatic plants before they enter the holding vessel or in the holding vessel. The portion of thermal energy is a first portion, and the method-2 further comprises: directing at least a second portion of the thermal energy to the anaerobic digester vessel; removing liquid from the first portion of the aquatic plants and the first portion of the MSW before directing the first portions to the anaerobic digester vessel; and transferring heat from the removed liquid to heat at least one of the second portion of the aquatic plants and the second portion of MSW. The method-3 further comprises: holding a mixture of the aquatic plants and the MSW at an elevated temperature in the holding vessel; directing the mixture to the pre-processor; removing liquid from the mixture at the pre-processor; transferring heat from the removed liquid to a portion of the mixture entering the pre-processor; and transferring heat from the removed liquid to a portion of the aquatic plants entering the holding vessel.