Compost

Some years ago the City of Calgary came up with a two-pronged approach to dealing with compostable waste.  The idea was to reduce the need for ever-expanding the landfill, thereby reducing cost to the City.  So the City offered citizens access to durable composters for a somewhat subsidised cost.  I think it cost me about forty dollars, a one-time cost. 

I thought it was a clever idea, so I got one.  It’s amazing how well it works.  Only in the longest cold spells in mid-winter does it ever threaten to fill to overflowing.  The stuff just rots away to nearly nothing.  My friendly neighbourhood horticulturist then harvests rich, black loam out of the bottom of the composter.  

Interestingly, landfills seal up whatever is deposited there so well that compostable waste does not compost.  The stuff lasts relatively intact for a very long time, years. 

Many years later, the City then introduced the Green Bin program, wherein compostable material can be deposited into the bin to be picked up every week or two by a City tandem axle truck that closely resembles a typical garbage truck.  The material is then taken to a huge processing plant where it is turned into at least two great products, loam and methane.  The loam is sold as black soil which it is.  The methane is managed to avoid putting this potent greenhouse gas into the atmosphere.  The Green Bin program costs me a fixed amount every month, whether I use the Green Bin or not. 

Thus my costs are fixed and whether I use one or the other at all or in varying amounts, the cost to me does not vary. 

With the Green Bin I have the opportunity to deal with compostable materials that compost very slowly such as bones from food waste, evergreen tree needles and seed cones, stout branches, twigs, woody garden plants and other like stuff.  Even waste food oils and fats can be composted this way without creating an odor nuisance or attracting vermin.  However, I continue to compost almost all other kitchen waste in my little composter in my back yard.  

All of this seems eminently sensible.  

However, every time I carry stuff to the composter, I am struck with the thought that I am contributing to global warming.  You see this albeit small composter is rotting food waste, generating, just as in the case of the City’s facility, loam and methane.  The loam is not an issue.  The methane is an issue.  

So how much methane does this little composter generate, not enough to maintain a small flame, is my guess.  But does it contribute more heat trap in that green house gas than is contributed by the extra carbon dioxide generated decelerating and accelerating a fifteen tonne truck?  I have some experience with these trucks and I know that breaking inertia with this kind of mass really kills fuel economy, thereby generating more carbon dioxide than would be the case where speed is maintained at a steady pace.  So all I am talking about is that extra carbon dioxide generated by stopping to pick up the Green Bin, empty it into the truck, then accelerating to get to the next Green Bin.  

Also the composter is generating methane and the truck is generating carbon dioxide.  Methane is eighty four to eighty seven times more potent as a greenhouse gas over a twenty year period.  I think that means the truck has to emit eighty four to eighty seven times as much carbon dioxide as the amount of methane the composter emits.  I think there are clever engineers who can determine exactly how much carbon dioxide is emitted by stopping and starting that truck.  I suspect there are clever scientists who can determine how much methane my composter emits.

Can I figure these things out?  Nope, not a chance.  So how do I make a decision as to which is better to use.  Incidentally, I only put the Green Bin out for collection when it is full, which has amounted to about four times per year.  Therefore the truck starts and stops for my Green Bin about four times per year.  The composter has stuff added to it almost once every day.  Of course, if I did not use the composter the Green Bin would require emptying more often.  I have no idea how much more often, but definitely stopping and starting the truck more often.

Maybe all this does not matter, after all how much contribution to global warming can a little old composter make?  As I said, I don’t know, but when I multiply this by say three hundred thousand  households, what about that volume?  Obviously I still do not know, but I do know that when we talk about multiplying by three hundred thousand, we might begin to talk about a real difference. 

Strangely, to me anyway, this crazy thought crosses my mind every time I go to the composter. Yet I still go to the composter every day without having any idea which of the two options available to me are better for the environment, which is the only consideration with a meaningful option.