As the climate change talks in Paris continue a number of cities have made green pledges. Amongst those in the UK making green pledges include Edinburgh, Manchester, Newcastle, Liverpool, Leeds, Nottingham and Glasgow. They claim that by 2050 (why is it always 2050?) they will be 100% renewable powered. Other cities around the world have made similar green pledges (Copenhagen, New York, Sydney, Malmö and Munich for example).
The question is what do these pledges mean in practice? If you think about your town or city there is far more than electricity. There is transport, heat, “stuff” and of course food. All these would have to go renewable in my view for these green pledges to mean anything. Electricity will be a challenge in of itself. Does it mean the equivalent of 100% of electricity will be generated locally? Largely by solar panels in the day. Does it mean this energy will be stored and used overnight? Or does it mean the electricity will be exported at certain times of day and then imported the rest of the time reaching an equivalence? Details are few and far between.
Its perfectly possible to see most transport being by bike or electric vehicles/trains within a city, but what happens with visitors when they visit in a fossil fuel vehicle (if they still exist). Are they included in the total? The biggest challenge is food which should be included in my view. Its not going to be possible to grow all a cities food within its environs. The best we can hope for is for a sizeable contribution, even given some of the innovative ways people have found that have been covered by this blog to grow food in cities.
The biggest problem we found in our book was regarding green heat. On the news this morning the Parisians have been showing off water source heat pumps. Whilst these may achieve the COP values (no pun intended) the technology is very disruptive to retrofit.
I strongly support these green pledges made by cities, but I think we need to be honest and accept that we can only get part way on many of them. Nevertheless unless you aim high you will never achieve anything.