The Wairakei plant discharges approximately 6.5 times as much heat, 5.5 times as much water vapor, and 0.5 times as much sulfur, per unit of power produced, as would a modern coal plant in New Zealand. It also contaminates the Waikato River with H(2)S, CO(2), arsenic, and mercury at concentrations that have adverse but not calamitous effects. Designed and built at a time when environmental sensibilities were less acute and geothermal technology was less developed, Wairakei produces an overall environmental impact that would be neither acceptable nor necessary in a new plant. Despite its imperfections, however, the Wairakei plant has been under development or in operation for more than 20 years without presenting any serious environmental problems for the local population. Reinjection of the hot waste water, an as yet unproven procedure for liquid-dominated fields, would reduce the plant's environmental impact sharply. Ground subsidence is not a severe problem at Wairakei but may prove to be one at the nearby Broadlands field. There are several environmental characteristics that are unique to geothermal power: (i) pollutant formation may be independent of the power productionc rate; (ii) effluent pathways may change abruptly; (iii) preoperational testing and wild bores contribute significantly to the overall impact; and (iv) waste water may be discharged at temperatures high enough so that utilization of the waste heat becomes both practical and imperative.

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A molecular lifetime apparatus was used to study energy transfer processes of the C 3Πu state of nitrogen. Kinetic and luminosity measurements as a function of pressure indicate a cross section σ(3) = 2.5 ± 0.7 Å2 for vibrational relaxation of N2(C 3Πu)υ′=1 by ground-state nitrogen molecules. A useful result of the kinetic analysis is that although the observed lifetime (including quenching) decreases with υ′, vibrational relaxation reduces the gross C state luminescence decay to a single exponential, characteristic of the υ′ = 0 level. Natural radiative lifetimes and electronic quenching cross sections, σ(2), were determined for the υ′ = 0 and υ′ = 1 levels of the C state: υ′ = 0: τ = 40.5 ± 1.3 nsec and σ(2) = 1.98 ± 0.02 Å2; υ′ = 1: τ = 44.4 ± 1.4 nsec and σ(2) = 1.42 ± 0.71 Å2. Estimates of electronic and vibrational deactivation cross sections for the υ′ = 2 level are υ′ = 2: σ(2) = 3.9 ± 0.8 Å2and σ(3) = 1.6 ± 0.4 Å2. The efficiencies for excitation of the υ′ = 0 and υ′ = 1 levels by the secondary electronsproduced by fission fragments are in the ratio 1.0:0.44. It is argued that the C 3Πu(υ′ = 1) state deactivates in two ways through a common N4 intermediate, viz., C 3Πu(υ′ = 1) + X1Σg+(υ′ = 0) ± N4(C2υ)→ lim IB 3Πg(υ″ = ξ) + X 1Σg+(υ″ ≥ 0) → lim IIC 3Πu(υ″ = 0) + X 1Σg+(υ″ = 0) and that the strong vibrational relaxation is accounted for by a nonadiabatic mechanism originally proposed by Nikitin for vibrational relaxation of ground-state NO.

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