| Title | Kawerau Direct Heat Use: Historical Patterns and Recent Developments |
|---|---|
| Authors | Mr Andy Bloomer |
| Year | 2011 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | Kawerau, direct heat |
| Abstract | Ngati Tuwharetoa Geothermal Assets Limited (NTGAL) is the owner of the Kawerau steamfield, which currently supplies about 300-t/h of raw geothermal steam and 20-t/h of clean steam to the mills. Mighty River Power operates the steamfield on behalf of NTGAL. Geothermal process steam has been supplied to the mills since 1957. The steam is used in the pulp and paper process, for timber drying and for co-generation. Some of the steam is used in heat exchangers to generate clean process steam. An innovative technique developed by Norske Skog Tasman (NST) uses stripped geothermal condensate as feedwater for the heat exchangers . Raw geothermal steam is used in kilns for timber drying. Recently there has been renewed interest in the use of geothermal steam for industrial processes and NTGAL is working with existing and potential new users to provide geothermal energy in different forms. NTGAL has recently constructed a purpose-designed heat plant to supply clean steam to SCA’s tissue mill at Kawerau . This plant was designed to have very high reliability. It also uses the NST condensate stripping process to provide feedwater, which has been refined. Design is progressing on pipelines to supply separated geothermal water (SGW) and steam to a binary power plant to be constructed by NST. The SGW that will be used is a by-product of the steam supply and some is currently being discharged to the Tarawera River without the heat being extracted. There is increased interest for raw geothermal steam for timber drying, which is likely to result in an increase in the high-pressure steam capacity. |