Why are anaerobic digesters in the United States trending toward large scale, capital intensive developments versus small scale, perhaps even residential or household style units?
The short answer from economics 101 is supply and demand. Given that this technology is relatively under-utilized here in North America, there is so much food waste still going to landfills that it makes sense to provide large scale solutions to such a large scale problem.
Consider the average American throws out about twenty pounds of food per month, and that doesn’t include food waste up the supply chain from retail to wholesale to production. It is not unusual for a food processing facility or even a single store to produce many tons of food waste in a single day. The sheer volume of this material and the relatively untapped ‘market’ for food waste means the demand for a solution so far outweighs the supply that large scale is the best course for investment dollars.
Perhaps in another ten, twenty, or thirty years, when large scale anaerobic digestion facilities have proliferated and begun to make a real dent in our problem of food waste going to landfills, and in the course of that action even begun to make a tangible contribution to the domestic energy crisis, then developers and entrepreneurs may start looking for smaller niche markets to bring this solution to.
For now, as the supply (AD capacity) remains miniscule relative to the demand (food waste going to landfill), it makes the most sense to think big.