Portable energy for heat production could, of course, be supplied with conventional batteries, so a comparison seems appropriate. A cost analysis indicates that on a per calorie per test basis, using CaO as a thermal battery is several times less expensive than mass-produced, disposable, dry-cell batteries. Costs are scaled by the projected number of analytical runs possible and include both energy source and control hardware. CaO disposables are single use, while dry cells are expected to last five runs based on their energy density (four D-cells would be required). Two grades of CaO (reagent grade and soap grade), with an EPCM are compared to three possible dry-cell implementations (with an EPCM, with microprocessor closedloop control, with thermostat closed-loop control). With a projected cost per run of US$0.56, the soap-grade CaO/EPCM combination is clearly the least-expensive alternative (compared to $1.40, $1.17, $1.21, and $1.16 for reagent-grade CaO/EPCM, Dcell/EPCM, D-cell/microprocessor, and D-cell/thermostat, respectively.) Costs were estimated from MSRP. Increased value of CaO over the alternatives could be realized at increased production volumes. Any special disposal or recycling required does not seem any more onerous than what is required for common batteries.