A central theme in many of our projects is the quantitative assessment of microbial reaction energetics. We use thermodynamic and kinetic models across numerous temporal and spatial scales. Current projects include a global description of marine sediments as habitats for microorganisms, predictions of potential but as yet undocumented metabolic strategies, and energy requirements for biomass synthesis in numerous natural environments. A new and very exciting focus in our lab is on microcalorimetry. Early projects include high precision measurements of heat production by a) the bacterium Shewanella grown on different energy sources and b) the natural community of microorganisms in basement fluids from the Juan de Fuca Ridge flank system. Another new project is a laboratory investigation to better understand metabolic competition in light of energy yields and energy requirements.