Estrategias de recogida y registro de datos

The ExtemE Report (ETSU & 1ER, 1994) (hereafter referred to as the Report) estimates damage costs for two coal-fired power stations: Lauffen in Germany and West Burton in the United Kingdom. The damage estimates o f the health effects o f particulates and acidic aerosols emitted from West Burton are rather limited, in that they only include damages incurred in Britain. In contrast, the estimates for Lauffen are much broader and include damages for the whole o f Europe. Thus, for the purposes o f this study, the latter estimate will be employed.

The emissions from Lauffen are reported as:

SO2: 800 g/MWh„

NO,: 800 g/MWh„

(These are only stack emissions, i.e. from the actual energy generation. Total emissions, including emissions from other sources such as coal mining, transport, etc. amount to: 830 g S0 2/MWhc, 927 g NOx/MWh^ and 353 g particulates/MWhç,. However, according to Watkiss (1995), the damage estimates are based on stack emissions only.)

M ortality Effects fro m Particulates - PM^q

The emissions o f particulate matter are measured as total suspended particulates (TSP) in the Report, yet the damage estimates relate to PM^o, particulate matter o f a diameter o f 10 fim or less. There is increasing concern over the health implications o f particulates o f 1 0 /xm or less, as the smaller the particulate matter, the deeper the penetration into the lungs and, thus, the greater the potential for damage. The concern is partly centred on the belief that the particulate matter acts as a form o f chemical ‘Trojan’ horse, conveying other pollutants deep into the lungs, where the synergistic effects cause greater damage (Humphreys, 1996). This explains rising concern over particulate matter o f 2.5 ^m or less.

A conversion factor from TSP (total suspended particulates) to PM^o suggested by American studies is 0.55, i.e. the damage from one unit o f TSP equals the damage caused by 0.55 units o f PM^g. However, the Report argues, that for particulate matter in the plume from the power stations, a more appropriate conversion factor is 0.9. The reason for this, presumably, is that pollution control equipment fitted to the stack is successful in capturing a large proportion o f the larger particles, allowing only the smallest particles, almost all o f which fall within the PM^o category, to escape. This implies that the damage caused by 200 g o f particulate matter can be taken to be equivalent to that caused by 180 g o f PM^g.

The valuation estimate reported for acute effects on mortality reported for PM^g is 2.1 mECU/kWh (with a low level o f confidence^).

The Report categorises confidence levels as high for impacts quantified to a certainty well within an order o f magnitude, medium for order o f magnitude level certainty and low for other cases. Confidence levels were derived through sensitivity analysis and expert judgement, (ETSU & 1ER, 1994).

Thus,

2.1 mECUIkWh ^ u g g ? ECUItorme fM ,,, 180 g PM^JMWh

N o estimate is given for chronic effects on mortality from PM^o, which suggests that the 11,667 ECU per tonne is an underestimate o f the total mortality effects from PM|o.

M ortality Effects fro m Acidic Aerosols

Effects o f SO2 and NO^ are only included in so f a r as they contribute to PM^q levels

through the formation o f sulphate and nitrate aerosols. Relationships which thus link effects directly to SO2 and NO^ have thus not been used (ETSU & 1ER, 1994). The

model used in the Report, estimates the separate effects o f PM^o and acidic aerosols, thus allows adding the two damage estimates together without double counting (ETSU & 1ER, 1994 and Watkiss, 1995). The type o f modelling employed also implies that the Report is unable to distinguish between damage attributable to SO2 and NO, respectively; only jo in t damages caused by acidic aerosols are reported. Further work on this issue is likely to be carried out as part o f the next instalment o f the ExtemE project due to commence November 1995 (Watkiss, 1995). At the time o f writing (March 1996) no consensus had yet been established as to whether health impacts caused by acidic aerosols are related to the volume or the acidity o f the aerosols. In the absence o f further evidence, the fraction o f the damage attributable to each pollutant will be calculated on the basis o f their acidity.

Eyre (1994) states that the damage caused to buildings is due to acidity, and thus the best way o f apportioning damage between the two gases would be on the basis o f their contribution to acidity. Eyre (1994) further states that:

32 kg o f SO2 gives 1 kg o f acidity, and 46 kg o f NO , gives 1 kg o f acidity.

Therefore (46/32 = ) 1.44 kg o f NO, can be considered as having the same acid impact as 1 kg o f SO2. In the absence o f any consensus on how the damage to receptors other than buildings, can be apportioned to SO2 and NO , respectively, it

is henceforth assumed that all damage caused by acidic aerosols can be apportioned to the two gases using this relationship; i.e. the emissions o f NO , should be divided by the conversion factor o f 1.44 to give the equivalent amount o f SO2.

The Report estimates the total acute effect on mortality from acidic aerosols at 7.83 mECU/kWh (low confidence level). However, as indicated above, how much o f that damage should be attributed to SO2 and N0% respectively has not been specified. But using the relationship above and the actual emissions o f SO2 and N0%, an estimate for the proportion o f total damage that should be attributed to each pollutant can be obtained.

The first step is to normalise the emissions o f N0% to be expressed as emissions o f SO2 (based on the above relationship between damages), and add up the total emissions measured as SO2:

SOOg + SOOg/1.44 = 1356 g SO2 equivalents/MWhç,

Thus, 800/1356 = 59% o f the damage can be attributed to SO2, while (800/1.44)71356 = 41% can be attributed to NO*. This would mean that the damage estimate for acute mortality effects from SO2 would be 59% o f 7.83 mECU/kWh which is equal to 4.62 mECU/kWh. The comparable estimate for NO* would be (41% o f 7.83 mECU/kWh) 3.21 mECU/kWh.

To convert these estimates into ECU per tonne requires the following calculations: 4.62 mECU/kWh/800g S0 2/MWh = 5 J 7 4 ECU/tonne o f SO2, and 3.21

mECU/kWh/800g N O /M W h = 4010 ECU/tonne ofNO^.

Morbidity Effects fro m P M 1 0

The Report estimates acute morbidity effects o f PM^o as 0.446829 mECU/kWh (medium confidence level) and the chronic morbidity effects are reported as 0.0224 mECU/kWh (medium confidence level). This gives a total morbidity effect from PMio o f 0.469229 mECU/kWh. Assuming this estimate is based on 180 g

PMi(/MWh ( = 200 g TSP/MWh), the unit damage cost due to morbidity effects is (0.469229 mECU/kWh)/(180g PM,o/MWh) = 2,607 ECU/tonne PMiq. Thus the toted value estimate f o r health effects caused by PM^o comes to (11,667 4- 2,607) 14,273 ECU/tonne ofPM^o.

Morbidity Effects fro m Acidic Aerosols

The acute morbidity effects o f acidic aerosols are estimated at 1.64834 mECU/kWh (medium level o f confidence) and chronic effects are estimated at 0.082 mECU/kWh (medium level o f confidence), bringing the total morbidity effects o f acidic aerosols to 1.73034 mECU/kWh. The employment o f the same relationship as for mortality effects results in 59% o f 1.73034 mECU/kWh = 1.021 mECU/kWh can be attributed to SO2, while 41% o f 0.709 mECU/kWh can be attributed to NO,. Relating these damage estimates to total emissions, the unit damage cost for morbidity effect comes to 1,276 ECU/tonne for SO2 and 8 8 6 ECU/tonne for NO,. Adding up mortality and morbidity effects, the total health effect is then estimated at (5,774 + 1,276) 7,050 ECU/tonne f o r SO3 and (4,010 + 8 8 6) 4,896 ECU/tonne

f o r NO^.

A3.1.2

Effects on Agricultural Crops

The Report suggests that the most serious impact o f air pollution, arising from the fuel cycle, on agricultural crops, is likely to be mediated through foliar uptake o f SO2 and O3. In addition, it notes that soil acidification is also a major concern in northern Europe. Thus, it assesses the effects o f SO2 and acidi^cation o f soils for West Burton, and the effects o f SO2 and O3 for Lauffen. It notes that nitrogenous pollutants are regarded as being relatively unimportant for agriculture, although there may be synergistic effects with SO2 and O3.

Table A 3.1.1 lists both the reported SO2 damage estimates on agricultural crops for Lauffen and West Burton in mECU per kWh, and the reported emissions o f SO2 per kWh electricity produced. The effects o f O3 are excluded from the table, partly because the damage has not been estimated, and partly because O3 emissions are not included in the life cycle inventories for MSW treatment. From the damage estimate

and the emissions, the damage estimate for one tonne o f SO2 emitted is calculated. Note that the damage estimate for Lauffen is just over double the estimate for SO2 emissions from West Burton. There appear to be two reasons for this disparity; firstly, the Lauffen estimate includes damage to wheat, barley, rye and oats, whereas the West Burton estimate includes only damages to wheat and barley crops. Secondly, the West Burton estimate includes UK damages only, whereas the Lauffen estimate includes transboundary damages ( - although only for an area o f 159 x 171 km).

Table A 3.1.1; Agricultural Crop Damages Lauffen

(incl. transboundary effects)

W est Burton (UK damages only)

SO2 damage estimate 0.035 mECU/kWh^ 0.022 mECU/kWh^

SO2 emission 0.8 g/kWh 1.1 g/kWh

Damage/tonne emitted 44 ECE/tonne 20 ECU/tonne

Includes damages to wheat, barley, rye and oats.

Includes only damages to wheat and barley. The ExternE Report furthermore estimates the costs o f soil liming to alleviate effects o f acidic deposition at 0.004 mECU/kWh - this cost has not been taken into account here.