Kiribati welcomes largest desalination plant amidst climate threat
Though situated in the middle of the Pacific Ocean, Kiribati is a country that lacks water.
In South Tarawa, capital of the atoll country where around half of the population live, piped water supply is only available for two hours every second day; and some areas do not receive any water. The existing groundwater water source, already insufficient for the growing population, is at risk from climate change. Inadequate water supply and sanitation, compounded by overcrowding in the dense urban center, have led to high rates of diarrhea and other waterborne diseases.
An upcoming water supply project is set to turn things around in South Tarawa. The Asian Development Bank (ADB), World Bank, and Green Climate Fund (GCF) have banded together to support the government in constructing the largest desalination plant in the Pacific Islands. The proposed investment is valued at about $60 million – all in the form of grants.
The project includes a new seawater reverse osmosis desalination plant, with energy consumption offset by a new solar photovoltaic plant. The desalination plant will have an initial capacity of 4,000 cubic meters per day (m3/day) and is expected to be completed around 2022. The project also includes new and rehabilitated water supply network infrastructure, 5-year operations and maintenance (O&M) support for the desalination plant and network, as well as support for capacity development in key institutions.
What is desalination?
Desalination involves removing salt and other contaminants from seawater (or river water, wastewater, etc.) through thermal or membrane processes. The final product may be used for household consumption, commercial, or industrial uses. Although more costly relative to conventional water treatment processes, desalination is seen as a viable, alternative solution that has potential to provide sustainable water supplies, particularly in contexts of extreme water scarcity or where the only alternatives may involve importing freshwater or pumping water over long distances.
According to the International Desalination Association (IDA) Water Security Handbook 2018–2019, experts project that 2019 will see the most active growth in seawater desalination since the late 2000s. The handbook also noted that 1.9 million m3/day of seawater capacity was contracted in the first half of 2018, up 26% over the same period in 2017.
Desalination in the Pacific Islands
According to a study by the Pacific Islands Applied Geo-Science Commission, desalination has been used in the Pacific islands since the 1990s; though most plants have been small-scale. The remoteness of the Pacific Islands compounds logistical and O&M challenges. Electricity demands of desalination have also limited wider adoption of the technology, given that power systems in the region have traditionally relied on imported fossil fuels, which has high costs compounded by long supply chains.
However, the region may hold promise. In Ebeye, an atoll in the Republic of the Marshall Islands which (similar to South Tarawa) faces significant challenges with water scarcity, ADB recently supported the design and construction of a new 1,600 m3/day desalination plant. This is the only viable source of drinking water since the only alternate source for the population of 10,000 is importation.
Climate adaptation via desalination
In the 49th Pacific Islands Forum in September 2018, leaders from various countries in the region (including Australia, New Zealand, and Kiribati) reaffirmed through the Boe Declaration that “climate change remains the single greatest threat to the livelihoods, security and wellbeing of the peoples of the Pacific”.
Kiribati contends with critical challenges due to its vulnerability to climate change and disasters triggered by natural hazards. Sea level rise is of particular concern, with most land less than 3 meters above sea level. The quality and quantity of freshwater provided by South Tarawa’s two freshwater lenses (layers of fresh groundwater that float on top of denser saltwater, around 1 to 2 meters below sea level) are seriously threatened by climate change-induced inundation and extreme weather events including prolonged drought. The simultaneous or successive occurrence of inundation and drought could significantly impact the yield from the groundwater lenses. “Considering these factors, and taking a precautionary approach, the lenses cannot be relied upon as the main source of water in a future with climate change,” said Alex Conroy, ADB urban development specialist and team leader, citing ADB's proposal to the Green Climate Fund.
Seawater reverse osmosis desalination presents a practical and affordable longer-term option for supplementing water supplies and addressing demand. Desalination is seen as means of climate adaptation, given its capacity to improve resilience to water quality degradation.
Based on recent studies, she added, seawater reverse osmosis desalination presents a practical and affordable longer-term option for supplementing water supplies and addressing demand. Desalination is also seen as means of climate adaptation, given its capacity to improve resilience to water quality degradation and diversify existing water supplies independent of rainfall.
The planned solar power plant will also minimize the production of greenhouse gas emissions associated with running the desalination facility, while reducing the operational costs associated with electricity production.
As for environmental impact, assessments have concluded that as long as the proposed mitigation and monitoring measures are fully implemented, any environmental impacts will be site-specific, localized, and largely created during the construction period. “Waste brine from the desalination plant will be routed from the desalination plant to an existing outfall, where it will be combined with sewage and disposed to the ocean. Assessments conducted during project preparation have shown that prompt dilution of the waste is expected and the impact from brine disposal will be limited and localized,” explained Conroy.
Clean water for Kiribati
The South Tarawa desalination plant will be the largest in the Pacific to date in terms of capacity, and will be designed with a provision for expansion of up to 6,000 m3/day when demand necessitates. Upgrades to water supply network infrastructure through the project will reduce leakages and ensure all residents have access to clean water supply. The project also includes a comprehensive and intensive 5-year water, sanitation, and hygiene (WASH) and climate change program, which will have strong involvement of civil society organizations.
As the project awaits approval, ADB is currently assisting the government through a project design advance grant of $2 million, advanced from the $15 million grant allocated to the project. Under this phase, design and procurement support is being provided to the government. This is expected to facilitate a smooth transition once the main project kicks off, minimizing contracting delays and speeding up disbursement.
The project builds on the recent Kiribati Adaptation Program Phase III in which three water supply zones in South Tarawa were rehabilitated and now have continuous water supply.
Conroy said: “The project will address factors resulting in the high incidence of waterborne disease in South Tarawa through the delivery and effective management of new and rehabilitated climate-resilient water supply assets and improved hygiene practices.”