The sun’s energy causes water to evaporate as it rises up through the atmosphere. This water vapor then condenses into dew and rain.
These processes form the basic desalination process – the separation of fresh and salt water.
The Adelaide Desalination Plant provides an alternative water source that is not dependent on the climate, and relieves pressure on groundwater, surface water and River Murray supplies during drought.
Water Scarcity
There’s no doubt that the drought situation in rural South Australia has been severe and has affected many people. It’s a crisis that needs to be addressed and quickly.
The current drought is a result of the El Nino weather phenomenon that has led to lower than normal rainfall across the state, and particularly in rural areas. The drought has had significant impact on agricultural production and has seen a large decline in water storage levels, affecting communities and regions across the state.
In some cases, communities are being forced to rely on contaminated groundwater sources for their water supply. Others are able to tap into their local council-managed scheme and buy in bulk. The Yorke Peninsula Council operates a small seawater desalination plant at Marion Bay, which produces 65 kilolitres of fresh water per day. This water is supplied to the Marion Bay Caravan Park, businesses and residents.
As the demand for freshwater increases in line with climate change, it’s important to ensure that our infrastructure keeps up. As an example, the new desalination plant at Kaltjiti on the Anangu Pitjantjatjara Yankunytjatjara (APY) Lands is supplying water to 220 people living in this remote community.
This type of investment in infrastructure is crucial to ensuring that our rural communities can continue to grow and prosper, even with climate issues or natural disasters. It’s especially important that our agricultural industries can continue to thrive under challenging conditions.
A key factor in ensuring that our agriculture sector continues to thrive is having access to reliable and affordable water. A reliable supply of water ensures that farmers can continue to produce food for the nation and that our consumers are able to have access to the freshest and most nutritious food products.
Water scarcity has had an adverse effect on many farmers and their families, and the government has taken swift action to help alleviate the situation. The Federal Government has promised to pay for the entire cost of ramping up the desalination plant in Port Lincoln and will also provide additional water to NSW irrigators below market rates to ease pressure on the region.
Contamination
The Adelaide Desalination Plant was constructed to safeguard urban water supplies and ensure that sufficient drinking water is available in extremely dry years. It provides a water supply that is independent of rainfall and will augment Adelaide’s water security alongside urban water supply from reservoirs, stormwater, sewerage and the River Murray.
Contamination of groundwater by human faecal waste is a significant problem for rural populations in SSA, as shown in the figure below. However, the occurrence of contamination at different scales makes it difficult to identify and resolve the various sources of contamination in groundwater systems.
In-situ sanitation, primarily in the form of pit latrines, is the dominant source of contamination of groundwater in rural SSA (see Table S1 of the electronic supplementary material). It is also a major contributor to the high disease burden associated with contaminated drinking water in SSA.
It is therefore essential to understand the sources, pathways and receptors of contaminant movement and to investigate ways to minimise the contamination of groundwater. One approach is to fingerprint contaminants using a combination of chemical, geochemical and biological processes. For example, nitrate levels can be used as a proxy for faecal contamination in urban groundwater. High nitrate concentrations are frequently observed in groundwater from sites that have high faecal indicator bacteria counts (Pruss-Ustun et al. 2014). This is because nitrate concentrations are less temporally variable than faecal indicators.
Nitrate and chloride are major contaminants at the desalination plant, consuming around 40% of total energy consumption during operation. Consequently, a large proportion of the plant’s energy consumption is generated on site using solar photovoltaic cells on each of the reverse osmosis buildings. Energy from the solar arrays is used to drive the pumps for the desalination process and for powering energy recovery devices which convert a portion of the energy extracted from the saline concentrate stream.
The construction of a second desalination plant near Port Lincoln is currently being considered as part of a plan to reduce the state’s dependence on mined water from the Great Artesian Basin and the River Murray. The new plant would be located in the northern part of the Spencer Gulf and provide a long term sustainable water supply for local communities. The project has been criticised by the blue mussel aquaculture industry, with a scathing scientific report from Flinders University calling for the plan to be abandoned because it will damage the industry.
Climate Change
Whether we like it or not, climate change is happening and its impact on water availability will become more apparent as time goes by. With increased global temperatures comes decreased rainfall, which is already occurring in parts of the country. This means less freshwater for drinking, washing, and agricultural use. Having access to desalination plants will give farmers the ability to continue their business even during times of drought.
The Barka 4 plant in Adelaide is capable of producing up to 100 gigalitres of water a year, enough to fill 40,000 Olympic-sized swimming pools. However, it is used very sparingly because of the high cost of converting seawater to freshwater. In fact, the federal government is currently paying the state government to crank up the plant and make more water available for farmers in the Murray-Darling Basin.
This deal is not making much sense, especially given that the plant will only make a tiny difference in terms of overall water availability and at a significant cost to the taxpayer. The cost of electricity to power the reverse osmosis desalination process is huge and is comparable to the amount of energy needed to power a Boeing 747. As such, the plant will require significant investment to maintain its capacity.
On top of that, the plant is vulnerable to changing weather conditions and other external factors, such as cyclones, which could cause disruptions in production and energy consumption. The plant’s designers are attempting to mitigate these risks by using energy efficient technology and incorporating thermal efficiency into its design. For example, the buildings at the plant are constructed with a combination of solid precast concrete walls and insulation to maximize thermal properties.
Another potential issue is that the saline discharge from the plant could harm or kill giant cuttlefish migrating to Point Lowly for their winter breeding season. Hundreds of thousands of these creatures migrate to the rocky waters of the Upper Spencer Gulf every winter, and they are a popular tourist attraction. An Infrastructure SA spokesperson said the company would assess the impact on the species before deciding whether to endorse the project.
Efficient Production
A desalination plant can be a great source of drinking water, however, it requires a lot of energy to run. The reverse osmosis process that it uses requires the power to break salt from its chemical bonds, which can be expensive in countries where there is not enough electricity produced. This is one of the primary reasons that we don’t see many more plants popping up around the world, as the cost is simply too much for most countries to justify.
The good news is that there are ways to reduce the amount of energy required, especially if you use technology like drip irrigation. This is where a series of pipes with small holes or emitters are placed throughout your farm, and it drips the water directly onto the roots of your crops. This method of irrigation is significantly cheaper and more efficient than traditional methods, and it also reduces weed growth and disease spread.
Another thing to consider is that a desalination plant can help provide water for irrigation of crops as well as livestock, which is a big bonus in arid areas where freshwater is scarce. This means that farmers can grow crops that they would normally not be able to produce, and this will make them more self-sufficient and independent. This will also help to keep food prices down for locals and tourists alike.
During the drought in Australia, there were calls for more desalination plants to be turned on, and it has now been confirmed that the Port Stanvac plant will be doubling its capacity from 50 GL/year to 100 GL/year, and this will result in one of the lowest operating costs per unit of desalinated drinking water in South Australia. This new plant is also set to be powered by 100% renewable energy from within Australia, which is a significant step forward for environmental sustainability.
However, a proposal to place a desalination plant at Point Lowly in rural South Australia has been flagged, and this could potentially harm some of the state’s most iconic natural features. The Conservation Council of SA has warned that a saline discharge from the plant could harm or kill thousands of giant cuttlefish, who gather there every winter to breed. This is a major concern, as these creatures are a huge economic draw for the area.