An Irish study that compares emissions per person across modes of transport shows not even cycling is completely benign, writes Paddy Comyn
YOU MIGHT always have assumed that cycling was an emission-free form of transport, and there is no doubt that it is probably the cleanest form this side of walking. However, an Irish report, entitled A Comparison of Carbon Dioxide Emissions Associated with Motorized Transport Modes and Cycling in Ireland, asserts that cycling isn't exactly emission-free.
It states that “cycling is widely viewed as a transport mode with marginal environmental impacts. However, such a view fails to take account of such factors as the increase in carbon dioxide exhaled as a result of increased physical activity or the emission embodied in the manufacture of the bicycle.”
The study goes on to say that when indirect energy is taken into account, a cyclist commuting an equivalent distance to work releases an almost equal amount of carbon dioxide as that attributed to a passenger of an electrically propelled train at full occupancy during peak service times.
The report states that a cyclist expels 5g/km of CO2 per passenger, and this compares with 11g/km CO2 per passenger on the Dart and 15g/km on an Intercity bus. The Luas performs less well, with 64g/km of CO2 per passenger. It concludes that normal SUV and private car transport results in greater than 10-fold the emissions per passenger kilometre of public transport by Dart or bus services, and that Luas emissions are four times greater than those caused by travel by Dart.
Speaking to The Irish Times, one of the report's authors Conor Walsh, a researcher at the University of Limerick's Centre for Environmental Research, said: "It might look from the report like we were trying to denigrate cycling as a model of transport, but the point we were trying to make is that no model of transport is completely benign.
“They all have an impact, even if it is small. But it also shows just how good something like a Dart is. It shows that using something like a Dart or Luas at full capacity can make a difference. Looking at normal emissions doesn’t always tell the picture, but you need to look at the emissions per person. An empty train is obviously worse than a train running at full capacity.”
Transport
A 75kg
cyclisttravelling at an average speed of 16km/h uses 0.5g/km of CO2.
Based on 945 passengers travelling at an average speed of 30km/h, the
Dartuses 10,220g/km of CO2.
An
Intercity bustravelling with 57 passengers at a speed of 70km/h uses 840g/km of CO2.
A
Dublin Bustravelling with 90 passengers at an average speed of 13.5km/h uses 1,450g/km of CO2.
A
Luastravelling with 235 passengers at an average speed of 70km/h uses 14,640g/km of CO2.
Based on an average mileage of 10,500km per year, a
scooterup to 125cc uses 850kg of CO2 per year; a
motorbikeover 125cc and up to 500cc uses 1,090kg per year; a
large motorbikeover 500cc uses 1,570kg of CO2 per year.
Based on an average mileage of 10,500km per year, a
Ford Focus1.4-litre petrol uses 1,650kg of CO2 (cost to offset is €16.50); a
Land Rover Range Rover3.0 Diesel uses 3,090kg of CO2 (offset €30.90); and a
Toyota Priususes 1,090kg of CO2(offset €10.93).
An average
car ferryproduces 48kg of CO2 per km
– Sources: Walsh et al, UL; Climate Care; Carbonica.org
Diet
A report from the Animal Science Journal says the carbon dioxide emissions from producing a single kilogram of beef are comparable to driving a car more than 250km.
Average meat eater: 2,190kg of CO2 per year
Vegan: 190kg of CO2 per year
– Source: EPA
Sport
An average
marathon runneremits 75g of CO2 per 41km: that's 1.82 g/km, which is 2.7 times the daily emissions that's the average for a human
– Source Tokyo Marathon
Methane
Methane is 23 times more powerful than carbon dioxide when it comes to global warming.
Each
cowproduces about 120kg of methane per year. Each
sheepproduces about 8kg of methane per year. Each
pigproduces about 1.5kg of methane per year
Each
humanproduces about 0.12kg of of methane per year.
Travel
The average shorthaul flight uses up 0.4kg of CO2 per passenger per km. This rises to 0.25kg of CO2 per passenger per km for medium-haul flights and 0.27kg of CO2 per passenger per km for longhaul flights. These figures can be doubled for business class passengers, and almost tripled for first class.
Return flights from
Dublinto
Paris(1,537km) = 190kg of CO2 per person
Return flights from
Dublinto
New York(10,208 km) = 1,410kg of CO2 per person - or more than a year's driving in a Prius
– Source Climate Care
