Zoos have always been one of my favourite places to visit. On my most recent visit, I started thinking about what happens to all the animal waste produced (working in a company that deals with waste issues will do that to you!). If you’ve ever been to a zoo or around an elephant you will have seen how much waste those guys can produce in just one ‘sitting’.
So how do zoos deal with their waste and are there any alternatives?
Most zoos in the UK have an environmental policy (some even have ISO 14001 – Chester and Paignton Zoo, some of the first zoos in the UK to show this kind of commitment to the environment). But these mostly concentrate on what happens to the waste that visitors dispose of; recycling systems for litter etc. but what about the organic waste that the animals produce?
Anaerobic digestion (AD) seems like the perfect solution. AD could help reduce the high energy bills caused by both heating to tropical temperatures and electricity. So why don’t more zoos use energy from waste systems, is just not worth the initial cost or have they just not caught up to the idea.
London Zoo has started to use their animal waste for energy. They have developed a process where over 2,760 tonnes of waste from herbivores is composted and used as high quality farm fertiliser. Waste from carnivores is converted into usable energy by an ‘energy from waste’ plant.
Munich Zoo have gone one step further and waste from all the herbivore animals is put into its own AD plant and produces 5% of the zoos energy needs and the digestate used as a fertilizer (most zoos simply use their animal waste as a fertiliser rather than extracting any potential energy from it before hand).
Of course the energy output of using energy from waste is small (only 5% of the Munich zoos energy is produced using elephant waste) so it is economic sense from a zoo to have their own AD plants?
Should more zoos be investing in energy from waste? The process works well for farms. Both arable and livestock farmers have benefited, so shouldn’t the same principles apply to a zoo, just on a much bigger scale?
Whatever zoos decided to do with their waste they are all committed to doing something to help the environment, which will go a little way to help those species affected by our previous actions leading to climate change.
Blog post by Erika Stelfox-Griffin