Carbon Footprints

Work in Progress

The things we buy and use in life have an undeniable impact on our environment. Some have a small impact, some large and some may even work towards having a positive one, the scale of these impacts are based on many factors. When trying to understand the effect we have on our planet we need to think about the journey the products we use took to get to us. We need to think of the entire journey from the items initial conception, through manufacture, use and all the way to its eventual destruction or decay. We call this type of analysis a Life-Cycle Assessment (LCA or Life-Cycle Analysis) and it is often referred to as a cradle to grave analysis. In this course you are going to take that journey with a product, thinking about the carbon footprints left behind as it makes its way to your home and what happens to it once you throw it away.

Our journey begins with the research and design of our product. Most designers work in nice light studios at a nice new computer, gone are the days of them using mainly paper and pen to design. Well that reduction in paper is a good thing but did you realise it takes around 55 watts of power to make one A4 piece of paper and around 200 watts of power to keep the average desktop computer running for an hour? Ever stared at that screen for hours trying to write that final page of that essay? Well if you have you definitely would have used less power writing it on a piece of paper. I bet you printed it out at the end too so you used that paper as well. We produce the large portion of our electricity in the UK through gas powered power stations which means that 200 watts of power released around 97grams of carbon into the atmosphere. That might not seem a lot but say that designer took 2 weeks to design the product and worked 8 hour days thats already 7.7kg of carbon we have produced not to mention the office lights or heating.

Lets move on to the next stage. We have designed our product and decided what materials to make it from so now we need to acquire those materials. Every material has a different Global Warming Potential (GWP) which is the equivalent amount of carbon released into the atmosphere for each kilogram produced. Lets imagine we are designing a water bottle which is made of plastic and specifically PET. The average water bottle uses around 13g of plastic to make and PET has a GWP of 5.56kgCO2/kg. This means each bottle we make releases around 72g of CO2 and this takes into account the extraction process of getting the oil out of the ground, and the processing required to turn it into plastic.

The next stage is getting the PET from the oil refinery to our manufacturing plant. This is hard to put a carbon figure on as it will depend on where these two locations are, how far they thus need to travel and importantly how they will travel. Different means of transportation release very different amounts of CO2 equivalent into the atmosphere. A modern lorry for example releases between 60 and 150g of carbon to transport 1000kg of cargo 1km while a train only produces between 30 and 100g per km. So lets pretend our plastic is refined in the UK in the largest PET production plant which is in Teeside and our manufacture plant is in Milton Keynes.  That is a journey of 210miles by truck which for our tiny bottle equals between 0.26g and 0.66g of carbon.

Now to manufacture it, which in our case will be done with blow moulding. Very smart people spend many hours trying to work out exactly how much energy is used in producing items, and modern production has many variable so its hard to make a perfect judgement of every process but in this case it takes around 13 watts to make one bottle. If you remember from earlier that equals roughly 6.3g of carbon from the production of the electricity.

Now our bottle of water is manufactured we need to get it to the consumer. Lets imagine someone on holiday in California is desperate for the taste of home so goes to his local store and purchases a bottle of our finest Milton Keynes water. How far has that bottle travelled and what impact has it had? Work out the two alternative ways of transporting that bottle.



488g CO2 /1000 x 200 = 97.6grams of carbon of p