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Spy glass

Friday 7 March - Saturday 8 March 2008
The Mall Galleries, Broadmead, Bristol

Science Alive! is the University of Bristol's contribution to National Science and Engineering Week. It is a biennial festival that provides an opportunity for people of all ages, from all areas and organisations to take part in science, engineering and technology activities. Scientists from all across the University are taking part from 7-9 March at the Mall Galleries in Bristol city centre.

Members of BRIDGE have created their own interactive science displays designed to explain climate and the effects of human activities.


Photo of Rita Wania


Rita Wania


This exhibit uses a variety of different sized inflated balloons to represent the levels of Carbon Dioxide (CO2) that are emitted as a result of different activities, such as using a car, train or plane. Details on the calculation of different balloon sizes are given in the Methodology section.

Every year one person in the UK produces enough CO2 to fill 2 hot air balloons, which is double the global average. The UK needs to reduce its CO2 emissions by 60% over the next 40 years and small measures can be taken by every individual to help reach this target. This includes using energy efficient lightbulbs, turning electrical equipment off instead of leaving it on standby and walking instead of driving.

Download Leaflet for more details on energy reduction and our contribution to CO2 emissions.


The balloon sizes were calculated as follows:

Balloon volumes:

  • 3ft Balloon = 400L (calculated, diameter = 0.91m)
  • Radio sonde = 524L (calculated, diameter = 1m)
  • Hot air balloon = 2.5 million L (from Wikipedia)

Hot air balloon image

CO2 emissions per energy source in CO2eq/kWh (source):

  • Wind 6.9-22
  • Photovoltaic 12.5 - 104
  • Nuclear 3 - 40**
  • Gas 398 - 499
  • Coal 500 - 1085

** The value of 126 g CO2/kWh for nuclear was cited in Spektrum der Wissenschaften with reference to the Oekoinstitut. This values looks like it is too high though as no other source stated it to be as high as this.

To get from g CO2 per kWh to a volume of CO2:

  • 1g CO2 = 0.0227 mol of CO2
  • 1 mol of gas = 22.4 L
  • 1g CO2 = 0.509 L
  • 1kg CO2 = 509 L

Train journey CO2 emissions: Details

Plane journey CO2 emissions: Details

Car journey CO2 emissions: Details 1, Details 2

Link to Science Alive webpage