Capturing and maximizing the value of waste resources on site requires integrating processes to turn waste from one component into an input for another component until all energy and nutrient value is recovered. Below is an illustration of the energy/nutrient cycles in a Carbon Harvest project.
For example, the Lebanon landfill project includes a 1.6 MW CHP system supplying heat to a 21,000 square foot greenhouse and electricity to the grid. Additional waste heat from the power plant will be piped to a neighboring asphalt plant in the summer and a concrete plant in the winter, in both cases replacing their need for non-renewable fossil fuels. The greenhouse will feature hydroponic vegetable production integrated with 100,000 gallons of recirculating aquaculture. Nutrient-rich fish culture water will be filtered and cycled through the hydroponic vegetable system in a closed loop. The only addition to this water-conserving process is make-up water to replace evaporative, filtration and harvesting losses. Sludge from the aquaculture system is the only byproduct, which is turned into a high-nutrient compost. Fish culture water is also fed to an algae culturing process for additional filtration before returning to the greenhouse.
An innovative design will capture a portion of the power plant’s exhaust gases, sequester CO2, SOx and NOx and use them to grow algae. If possible, the algae will be processed into biodiesel. Clean algae will be used to produce animal (fish and poultry) feed. The algae culture process water, along with any residual algae, is returned to the fish for feeding, and purified CO2 left over is sent to the greenhouse.