The recycling movement has tried to turn composting into a special process unconnected to anything else but the Zero Waste movement simply sees composting as one more design process for eliminating waste and inefficency from agricultural processes. It is a normal ZW activity.

Composting is a way to reuse the nutrients that come from soil in the form of food and fiber, back to the soil. It is the most quintessentially natural reuse method, and the only one that depends on the decomposition processes of nature. Though there is much talk of biodegradable plastics, that is a mistaken design. There are some industrial byproducts which can be turned back to agriculture in the short term, such as plaster (calcum sulfate) that provides a calcium supplement, but it would be much better to use the high purity calcium sulfate as a high purity input for industrial reuse, without degrading it in soil.

There is a movement, financed by the garbage industry, to replace aerobic composting with anaerobic digestion. Anaerobic methods, which require much more equipment and capital than composting, convert an insignificant amount of organic matter (less than 5% by weight) into methane which can then be sold and burned. And they use half of the methane themselves just for heating the pile, leaving less than 2.5% for capture. However, this allows the garbage companies to pose as energy producers while destroying all the much more significant values of a rich compost. The environmental movement needs to get more savvy about what is really going on. That means subjecting even green-sounding proposals to serious scrutiny.

One of the obvious values of compost is its ability to reuse natural nitrogen back into soil. I have therefore calculated the amount of energy used to produce synthetic nitrogen via the extremely energy intensive Haber Process for fixing nitrogen under high pressure and high temperature. The calculation shows that world synthetic nitrogen uses the output of 120 large power plants. This is the minimum standard against which methane generation must be measured. It is only a minimum because compost provides many other important values – not just nitrogen. See calculation. Surprisingly, it is estimated that natural nitrogen fixation worldwide fixes only half the amount fixed by synthetic methods.

As an order of magnitude, the question becomes: does anaerobic digestion produce anything like enough methane to run 120 power plants? If not, it is not in the same universe of energy saving as composting is. I doubt that any promoter of anaerobic digestion would dare to compare it to this standard. But the jury is still out.

It is worth mentioning that composting is not some magic solution, the best use of all organic matter.Often there are better uses for organic matter because it has a higher form, a low entropy Function, that can be exploited before turning to molecular disassociation i.e. composting. Maybe it is in the form of lumber. Maybe it is perfect for growing mushrooms on. Maybe it should be chipped and used for barbecue or cedar chest flavoring. Later it will still be usable for composting.