Using economics to beat air pollution

Press, 9 October 1982, Page 14

Using economics to beat air pollution

Research into Christchurch's air pollution problem has thrown another factor into the ring: the economic well-being of the community. The biggest influence on air pollution in the city during the winter .months remains the weather, but it appears some correlation exists between living standards and the Incidence of air pollution.

This is bad news for Christchurch in a time of recession. Apart from a few hiccups in the official readings, smoke levels in Christchurch declined steadily from 1960 to 1974. During this period New Zealand was enjoying an almost record standard of living, high economic activity, and very cheap electricity/

Towards the end of the 70s. smoke levels started to rise again. Pollution peaked in 1980. dropped markedly last year — a particularly good winter climatically, with few occasions of pollution-promoting or pollu-tion-retaining weather — and climbed again in the winter just past.

Two factors have the most effect on the level of smoke pollution: the weather, about which little can be done, and the number of smoking chimneys. Christchurch's worst winter for pollution, 1980, was marked by 44 days of ground frost. The cold, still air necessary for the frosts not only promotes home heating, includ-

ing open tires, but also allows the pollutants to hover over the citv.

By contrast, last year had only 24 days of ground frost and this has been assumed to be the main reason for the low levels of pollution then. This year the number of cold, still evenings increased and so did the pollution. Smoke' levels in the inner suburbs were almost as high as they were in 1980 i The World Health Organisation pollution standards are two-tier. The first tier sets a standard which actually measures the pollutants in the air: the second sets a maximum number of occasions during a defined period on which the W.H;O. pollution levels may be exceeded without being regarded as a persistent danger to health.

During the winter months in Christchurch, when pollution readings are taken, the W.H.O. levels should not be exceeded on more than seven occasions if the W.H.O. guideline is to be met. In 1980 the levels were exceeded on 34 occasions; in 1981 Christchurch came close to meeting the guideline when the levels were exceeded only nine times; in the winter just past they were exceeded 23 times.

The link between pollution and the economy is harder to quantify, but some factors seem relevant.

• Higher levels of unem-

ployment probably means more people staying at home on cold, wintry days in front of a fire.

• Less real wealth in sections of the community, and the regular appearance of power bills in which the home heating component is not readily identifiable. probably means a growing reluctance to use electricity for heating. • Less wealth probably means a slower rate of conversion from open fires to fuelefficient burners than would have been possible 10 vears ago.

• The tighter economy probably encourages the use of lower quality fuels and rubbish in open fires, with consequently worse pollution emissions.

The difference in price for different grades of coal, the lack of coke, and the ability to pad out open fires with other combustibles would allow worse pollution to come from even fewer chimneys.

Even some of the approved appliances contribute to pollution either because they are too efficient or because they are used improperly. Some cannot be dampened down to lessen their heat out-put without also lessening their efficiency and increasing smoke emissions.

The availability of scrap or windfall wood and newspaper logs, and the variable prices

for different grades of coal, make precise comparisons of home heating costs difficult.

Figures produced by the Clean Air Council in association with the Ministry of Energy. however, show that electricity has a definite advantage in cost over open coal fires for home heating. Not onlv must the cost of the fuel be taken into account, but also the capital cost of the system used and the thermal efficiency, or total heat, available from the fuel finally available to the room being heated. Electrical heating appliances are virtually 100 per cent efficient under normal circumstances. Some types, particularly storage and underfloor heaters, are wasteful in that they give out heat when not needed, and average about 75 per cent, but off-peak electricity for storage heaters is cheaper. Open fires are inefficient. Free-standing sheet metal open fires give slightly better efficiency (about 25 per cent) than the conventional brick fireplace (about 20 per cent) when using coal. Efficiencies of 15 per cent to 20 per cent are likely when wood is used as the main fuel.

Closed space heaters or incinerators are a lot more efficient than open fires and can give values of about 50 per cent on solid fuel. However.

they produce as much smoke as the open fire for the same amount of fuel burned.

Coal-fired heaters approved by the Clean Air Council produce less smoke than other types and can be about 60 per cent efficient in use. To maintain both their efficiency - and cleanliness some care is needed in their operation. Oil-fired appliances can be about 70 per cent efficient, but many existing installations are only about 50 per cent efficient. Regular annual maintenance is needed to ensure clean combustion and efficient operation.

When these two factors — the cost of fuel and the efficiency of use — are taken into account, the overall average cost of a quantity of "useful" heat delivered to a room can be calculated. This is how the Clean Air Council and Ministry of Energy arrived at the figures that follow. The figures show the relative costs of obtaining a kilowatthour of heat from a range of appliances, and include allowance for the repayment of the capital cost of the appliance over its expected life. The figures have been adjusted to costs in Christchurch as at the end of July, this year: Electricity 4.2 c Electric storage 3.9 c Coal: Open fire 8.2 c

Free-standing 6.6 c Approved heater 3.8 c Oil 7.3 c The apparent economy of the approved coal-fired space heater is bought at a high initial price, however, since the cost of these appliances, even with conversion loans, is considerably higher than for most electric heaters. The cost advantage of electricity could be increased even further if the Governments pricing policy for bulk electricity took more account of total units used rather than peak loadings, and if the price of coal for home heating was not held artificially low but allowed to rise to reflect more accurately the cost of production.

Even without this added impetus. the economic considerations in favour of electricityare persuasive enough to encourage the trend away from open coal fires. Convincing the public of these advantages appears to be a problem. Once the cost advantage is established in the public's mind, it should be possible to use the economic considerations now contributing to smoke pollution to reduce it. A mistaken belief that open fires are cheaper appears to persist. As soon as this is seen for what it is — a pennywise. pound-foolish argument — the number of open fires and air pollution should reduce.