Sharon Cullinane and Julia Edwards
IntroduCtIon
Logistics is responsible for a variety of externalities, including air pollution, noise, accidents, vibration, land-take and visual intrusion. This chapter examines these various externalities and discusses how their impact can be assessed. As climate change is now considered to be the most serious environmental challenge facing mankind, the main focus will be on greenhouse gas (GHG) emissions from freight transport.
In measuring the environmental effects of logistics it is important to distinguish first-order and second-order impacts. The first-order envi-ronmental impacts are those directly associated with freight transport, warehousing and materials handling operations. Second-order impacts result indirectly from these logistics operations and take various forms.
For instance, advances in logistics have facilitated the process of globali-zation so that goods are now sourced from previously little-developed parts of the world. Partly to accommodate the consequent growth in freight traffic in such areas, governments have expanded transport infra-structure and this has often encroached on sensitive environments. The increase in air freight and other traffic resulting from global sourcing is a first-order effect, whereas the increase in infrastructure, such as road building in sensitive areas, is a second-order effect. In this chapter we
concentrate on the first-order impacts and make only brief reference to the wider, second-order effects. Since the majority of the first-order impacts emanate from the transport of goods, rather than their storage and handling, the attention will focus on this activity. Chapter 8 specifi-cally examines the environmental impact of warehousing.
EnvIronmEntAl ImpACts Atmospheric emissions
Emissions from freight transport largely depend on the type of fuel used.
As discussed in Chapter 15, various alternative fuels now exist. However, the main fuel used by goods vehicles continues to be diesel, with rela-tively small amounts of freight moved in petrol-engined vans. Trucks and vans emit pollution mainly because the combustion process in their engines is incomplete. Diesel and petrol contain both hydrogen and carbon. If it were possible to achieve perfect combustion, 100 per cent of the hydrogen would be converted into water and all the carbon into CO2. However, because combustion is not complete, tailpipe emissions of pollutants such as hydrocarbons, carbon monoxide and nitrogen oxides result (Holmen and Niemeier, 2003).
In most countries, relatively small amounts of freight are moved in elec-trically powered road vehicles or freight trains. In the case of these opera-tions, the pollution arises at the point where the electricity is generated and the nature of that pollution depends on the primary energy source used. In countries such as France and Switzerland where only a small proportion of electricity is produced using fossil fuels, the carbon intensity of electrified rail freight services is very low (IRU, 2002).
Diesel and petrol have slightly different environmental impacts as their mix of pollutant emissions varies. Diesel engines emit more CO2 per unit of energy, but because they are more energy efficient, the overall impact of diesel engines on CO2 emissions is less than that of an equivalent-sized petrol engine (Schipper and Fulton, 2003). The standard fuel CO2 conversion factors for various types of fuel are given in Table 2.1. Diesel engines emit much higher levels of particulate matter and nitrogen oxides than an equivalent petrol-powered engine (Holmen and Niemeier, 2003).
It is difficult to measure emissions of particulates precisely, because of their ultra-fine nature. PM10 particles, for instance, have a radius of 10 microns or less (a micron is a hundredth of a millimetre). Measuring these particles when the vehicle is stationary is difficult enough; measuring them under different driving conditions and speeds introduces addi-tional complexities. Calculating the impact of these tiny soot particles
on human health presents further problems, although there is growing evidence of their effects on respiratory problems as well as on general morbidity (Pope et al, 2002).
The pollutants emitted by transport can be divided into local, regional and global effects (see Table 2.2). Local pollutants remain close to the source of the emission. At the kerbside of major roads, concentrations
table 2.1 Standard road transport fuel conversion factors
fuel type total units
used units × Kg Co2 per
unit total
Petrol litre 2.3154
Diesel litre 2.6304
CNG kg 2.7278
LPG litre 1.4975
Source: DEFRA (2008).
table 2.2 Geographical extent of pollutant effects
effect Pm hm nh3 so2 nox nmvoC Co Ch4 Co2 n2o global
Greenhouse –
indirect X X X X
Greenhouse – direct
X X X
regional
Acidification X X X
Photochemical X X X
Local
Health and air
quality X X X X X X X
PM – particulates, HM – heavy metals, NH3 – Ammonia, SO2 – sulphur dioxide, NOx – Oxides of nitrogen, NMVOC – non-metallic volatile organic compounds, CO – carbon monoxide, CH4 – Methane, CO2 – carbon dioxide, N2O – Nitrous Oxide.
Source: Hickman (1999).
of the primary pollutants can be two to three times higher than the background urban level, while inside vehicles travelling along major roads, concentrations can be on average five times higher than the background levels (RCEP, 1994). Regional effects can occur far away from the source of the emission and affect wider geographical areas, sometimes spanning several adjoining countries. GHG emissions, on the other hand, affect the global atmosphere. The same pollutants, such as sulphur dioxide or nitrogen dioxide, can have an adverse effect on the environment over differing distance ranges.
We turn first to the global effects as they have become the main cause of environmental concern. This is partly because scientific discoveries over the past two decades have revealed the severity of the climate change problem, but also because tightening controls on the emissions of other noxious gases have eased pollution problems at local and regional levels.