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  • (2002) Tukunga, Tevita
    Stand-alone photovoltaic lighting systems have been used to provide electricity in unelectrified remote locations in Tonga since 1987. PV lighting systems power many remote households and community halls and this improves lifestyles and upgrades living standards. Donors have spent millions of dollars to fund the purchase and installation of PV lighting systems in Tonga but this development is yet to prove its sustainability. This research examines the problems that influence the sustainability of PV lighting systems in Tonga and identifies problems related to their environmental, economic, technical and institutional sustainability. Proposals are put forward to enhance the future sustainability of Tongan PV lighting systems and related PV applications. The examination of sustainability employs the Brundtland definition of sustainability, viewing sustainability in terms of its environmental, economic, technical and institutional aspects. The research employs and analyses household surveys, data extracted from PV stakeholder interviews, and a literature search. The exploitation of fossil fuel and fuelwood resources is still significant in Tonga because the remote economy is a subsistence one, and environmental protection is not a priority. Lack of a proper recycling method for PV equipment increases the solid waste materials in the environment. Economically, users are reluctant to pay monthly fees, compounding problems with maintenance and access to spare parts. Social and cultural concerns have generally been ignored during system design and project planning. Technically, users experience poor system performance and some systems no longer operate. Institutionally, stakeholders have different perceptions and interests towards PV development in the islands. As a result, the By-Laws implemented to administer the PV lighting systems have never been enforced and stakeholders generally experience a low level of participation in governance, undermining their satisfaction with project implementation. The sustainability of PV systems in Tonga would be enhanced through the utilization of mature PV technologies under appropriate technological and institutional frameworks that reduce environmental problems and meet the socioeconomic needs of target communities.

  • (2001) Leung, Audrey
    The volatile aroma compounds in the green plant tissue and grain of five Australian rice varieties were studied in detail. Selected volatile aroma compounds, including 2-acetyl-1- pyrroline (AP), observed in three fragrant varieties, YRF 203, YRF 205 and Kyeema and two non-fragrant varieties, Pelde and Langi, were compared. The development of volatile aroma compounds in the rice plant was followed from early tillering to full maturity. The effect of nitrogen fertilisation level on the volatile aroma compound composition was evaluated. Volatile compounds were extracted by the Likens-Nickerson simultaneous distillation-extraction technique. GC-MS, GC-FID and GC-O were used to separate, identify and quantify the volatile aroma compounds in the rice grain and plant extracts. The 127 volatile compounds identified in rice plant tissue and grain included 28 aldehydes, 23 ketones, 20 alcohols, 8 phenolic compounds, 17 heterocyclic compounds, 7 hydrocarbons, 2 sulphur compounds, 5 terpenes, 11 acids and 6 esters. Most of the homologous series of aliphatic aldehydes, ketones and alcohols that were identified in cooked rice were also identified in plant tissue, but in different proportions. AP was the major volatile compound in fragrant rice plant and grain and was probably the major factor that contributed to the difference between fragrant and non-fragrant varieties. Relative levels of AP in rice plant correlated with the relative level of AP in the rice plant of the same variety. Therefore, AP concentration in rice plant tissue can be used as an early indicator of aroma in rice grain. The non-fragrant whole rice contained more pent-l-en-3- one, D-Limonene and hepta-2,4-dienal than fragrant rice, while fragrant rice contained more but-2-enal, hex-2-en-l-ol, pyridine and AP. Milled fragrant rice contained more but- 2-enal, pyridine, AP and pyrrole than non-fragrant rice. The increase in nitrogen fertilisation resulted in an increase of AP in rice plant tissue and grain in fragrant varieties. In addition, the increase in nitrogen fertilisation resulted in an increase in pyridine, hepta-2,4-dienal and 2-methoxyphenol in the mature rice plant and an increase of pentanal, hexanal, pyridine, heptan-2-one, pentan-l-ol, hexan-l-ol, oct-l-en-3- ol and furfural in milled rice. AP concentration was relatively high at the beginning of plant development and then decreased during plant development. Therefore, AP can be detected at the early stages of plant development, without having to wait until grain maturity.

  • (2004) Anderson, Timothy Nicholas