Andrew Scanlon Environment and Sustainability Manager Hydro Tasmania Drought and Climate Change

Tasmania, Australia

Hydro Tasmania Business Position Australia’s largest renewable energy generator. Australia’s largest dam owner. Australia’s largest water manager. One of Australia’s largest renewable energy developers. Australia’s largest renewable energy generator. Australia’s largest dam owner. Australia’s largest water manager. One of Australia’s largest renewable energy developers.

 29 small to medium size hydropower stations (2300 MW);  70 MW of wind power with another 200 MW under construction or planned;  Two diesel-wind systems on each of two offshore islands; and  A gas-fired thermal power station (120 MW) and 3 gas turbines (105 MW). Hydro Tasmania’s Generating System

Two Very Large Storages Lake Gordon Storage Capacity = GL or 22 Sydney Harbours Great Lake Storage Capacity = 3000 GL

Lake King William - Central Tasmania Large Seasonal Storages Above Cascades

Cluny Dam – South-eastern Tasmania Small-to-Medium Run-of-River Power Stations

Coping with Drought (1) A major drought occurred in the late 1960s – power rationing and low lake levels. Decision to provide thermal support – 240 MW thermal station commissioned in the early 1970s. Continued development of hydro system till fully developed in the 1990s.

Coping with Drought (2) Connection to the mainland power grid in 2005 (600 MW DC link). Diversification into wind power. Conversion of thermal station to gas and addition of three gas turbines. Drought conditions have persisted since the late 1990s.

Environmental and Social Issues Low lake levels, diminished downstream flows, and water quality problems present a range of environmental and social issues. These include: Lake and river ecosystem stress; Economic and social impacts on other users.

Great Lake (1)

Great Lake (2)

Risk Bands and Monitoring NMOL

Lagoon of Islands and Ouse River

Environmental Management - Lagoon of Islands Alternative water source for downstream users. Biomanipulation pilot study – early Remediation of Ripple Canal – Full-scale biomanipulation commences summer Investigation of options for new storages.

Climate Change and Water Supply – Adaptation Options Supply SideDemand Side More reservoir capacity.Water use efficiency. More groundwater use. Changed water use, e.g., different agricultural crops. Desalination. Water transfer. Price signal and water markets. Water recycling.

Climate Change – Hydro Tasmania Hydro Tasmania is reliant on water inflows and meets a customer demand that is, in part, dependent on climate. Hydro Tasmania has a multiple-use water resource with requirements additional to generating electricity. Hydro Tasmania has significant fixed assets including 44 large dams. Sustainable management requires an ability to predict likely future trends.

High Variability in Inflow

Climate Change – Looking Back

Climate Change – Looking Forward Climate change modelling study – CSIRO. Focus on impact of climate change on Hydro Tasmania and Tasmania. Better representation of Tasmania in modelling. Identifying trends in rainfall, temperature, evaporation and wind. Plan to implement outcomes into Hydro Tasmania models to estimate impacts to business.

Conformal Cubic Atmospheric Model (CCAM) Grid (+topography) Time step = 4 minutes Grid size– 11km 70 year simulation –10 million time steps –50 days on supercomputer –110 Gb storage

High Resolution Model Results Tasmania is in a region of reduced climate change compared to the global average. Climate change might be relatively moderate in Tasmania out to 2040; some warming and some change in rainfall patterns and winds. Result uncertainty due to the use of a single emission scenario, but the scenarios do not diverge very much by Some uncertainty from using a single rather than an ensemble of different global models.

High Resolution Model Results - Rainfall On a seasonal basis there is increased winter and early spring rainfall in all catchments. There is a drying trend in the north east in the first half of the year, only partly compensated by increased rainfall later in the year. Annual rainfall is projected to increase by 7-11% in all catchments except in the South Esk, which decreases by around 8%. South Esk

Factor of 1.0 represents no change in inflows. Factors <1.0 represents drying. Factors >1.0 represents wetter. Great Lake factors well below 1.0 and thus drying predicted. Others have drier summers/autumns and wetter winters. Hydro Tasmania Inflow Prediction

Climate Change Conclusions Strong evidence for a shift in inflows to drier summer/autumns and wetter winter/springs. Future predictions are showing similar trends. Potential significant reduction in annual/seasonal inflows in the central and easterly catchments. These shifts in inflows will result in a change to future operations of Hydro Tasmania. Probable Maximum Precipitation not examined (spillway capacity – dam safety issue).

Climate Change -- Future work Future work with Antarctic CRC: –Multiple emissions scenario. –Multiple climate models. Outputs of future work: –Rainfall trend estimates for modelling impact on Hydro generation. –Temperature variations for electricity and agricultural sectors. –Wind variability for wind farms and transmission authorities. –Extreme weather events for flooding and planning considerations.