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Maybe I'm just failing at finding the info, but does anyone know how much natural gas is used to create that 10kw of power? As the Stirling engine is a heat eng
by Sanddancer 12y ago
Maybe I'm just failing at finding the info, but does anyone know how much natural gas is used to create that 10kw of power? As the Stirling engine is a heat engine, my first thought is that one could potentially have a dual-mode generator here, using solar thermal, etc, to help generate power in those areas where it's amenable to do so.
- dredmorbius 12y agoStirling (and other thermal-cycle engines) are about 30-35% in converting heat energy to useful work. In this case electricity. So dividing 10 kW by 30% will give you the rough energy input. Casting that in therms/hr. (usual natural gas billing unit in the US is therms), it's about 1.14. Residential price is on the order of around $0.80 - $1.50/therm, so you're looking at about $25/day for 10 kW of continuous power. Which isn't far from what you'd be paying for electricity: $21 - 29 at $0.09 - $0.12 per kWh. In terms of volume, 1 ft^3 is about 1025 btu, a therm is 10,000 btu, so you're looking at 97.5, let's call it 100 ft^3 of natural gas consumption per day. As for running a Stirling engine on solar energy, or another heat source, yes, you could do that. Again, you need 33 kW of input power, which means a 33m^3 collecter surface -- that's 5.8m on a side, or 19 feet. Because the Stirling's hot end is a point, you'd need tracking systems or a working fluid to deliver heat to it from your mirrors. Incidentally, you can answer a lot of these questions using GNU units, written by Adrian Mariano. The great thing about it is conversion between different units and relationships, e.g., energy per hour per unit area. I find it invaluable in looking at energy, renewable, and related issues.