Desal: Too Much Power For Water

By Dr. Lijin Zhong, William Hua Wen, Ella Genasci Smith 13 January, 2015

WRI on why energy requirements for China's desal strategy could cost more than what most cities can afford

Desalination gaining attention in China

In fast-urbanizing China, nearly 90 percent of coastal cities face some degree of water scarcity and roughly 300 million rural residents lack access to clean water.

Desal target = 3 million m³ daily by 2020

To quench the country’s chronic thirst, the Chinese government has turned to desalination, aiming to produce as much as 3 million cubic meters of desalinated water daily by 2020, up from today’s 0.77 million cubic meter.

Desalination consuming more energy

However, a World Resources Institute (WRI) analysis shows that China’s desalination strategy would consume an enormous amount of energy, causing other problems such as increased greenhouse gas emission and air pollution, and would cost more than most cities can afford.

WRI analysis shows China’s desal strategy’s need for an enormous amount power  would cost more than most cities can afford

The cities of Qingdao and Tianjin – where per capita water availability is only 12 percent and 7 percent of the national average, respectively – have both commissioned desalination plants. Qingdao’s desalination plant was constructed by the Spanish company, Abengoa, in 2010, and is said to produce 100,000 cubic meters of drinking water per day for 500,000 people (roughly 25% of downtown’s population in Qingdao). Tianjin is home to the Beijiang and Dagang desalination plants, which together are expected to account for a third of China’s 1.5-2 million-ton capacity by 2015.

But desalination’s high-energy demand and steep CAPEX and operational cost challenge it as a sustainable environmental and economic  water supply approach. WRI conducted an analysis that looked at the different energy requirements for producing drinking water from various sources in Qingdao.

Desal plants consume 4 kWh/m³ of freshwater produced, while wastewater reuse requires <1 kWh/m³ 

On average, desalination plants consume 4 kilowatt-hours per cubic meter of freshwater produced, while wastewater reuse requires less than 1 kilowatt-hour of power to process the same volume and same quality of water.

The price of energy accounts for as much as half of annual operating costs, making the cost of operation of desalination plants prone to price volatility in energy markets.

Figure below shows that desalination consumes roughly 10 times more energy than required to extract and process local surface water in Qingdao, largely owing to the energy intensive reverse osmosis (RO) process to remove the salts. WRI’s research indicates that reclaimed wastewater requires much less energy and expense compared to desalination and long-distance water transfers from the Yangtze River.

In China, coal is the dominant energy source, accounting for approximately 79 percent of the total electricity produced in 2012. Therefore, consuming greater amounts of desalinated water would simultaneously increase greenhouse gas emissions. For example, if all 400,000 cubic meters of Qingdao’s proposed daily desalination capacity were in place, greenhouse gas emissions would increase by 80 percent per cubic meter of water produced.

Desalination should not be prioritized as the primary water sources for a city

Some countries, such as the United Kingdom and Australia have developed strategies to deal with the high cost and high energy demands of desalination technology. The United Kingdom, which opened its first large-scale desalination plant in 2010 with a capacity to supply water to up to 1 million people, only plans to supply desalinated water to the public in emergencies, such as droughts. During periods when it is not is use, it also doesn’t demand costly energy or emit GHGs and air pollutants.

UK & Australia’s experiences show that desalinated water should only be used as a backup source, and renewable energies could be used to power the desal plants

Australia, on the other hand, has looked to renewable energy to power the desalination plant. For example, the Perth Seawater Desalination Plant reduces greenhouse gas emissions by utilizing electricity generated by a wind farm.

Until desalination technology becomes more energy efficient, it should only be used as a backup source of water in China. Continuous government investment in complementary technology, such as renewable energy sources and energy recovery technologies, is also essential to reduce greenhouse gas emissions in desalination.

Water efficiency investments & wastewater reuse should be prioritized

Most important, to help alleviate water stress in China, other, lower-cost, and more environmentally sustainable water sources – such as water efficiency investments and wastewater re-use – should be thoroughly investigated first and prioritized in China’s water resources planning.

Further Reading

Desal in China

• Desalination: Proceed With Caution! – China is expanding capacity at a furious pace and by end of 2015 daily capacity is expected to be at 2.2mt/day up from 0.9mt/day in 2013, but Tommy Patterson from Kreab Gavin Anderson explains why investors should proceed with caution
• Chinese Desal Policies Reviewed – Dr Guo You Zhi, Secretary-General of China’s Desalination Association shares with us his insights on why desalination targets have not been met and what’s in store for the future
• Desalination: A Technology Driven Market – Amnon Levy, COO of IDE Technologies on the shape of desalination market and the technology challenges ahead. Is this the only way out of China’s water scarcity problem?
• Desal in China: Trends & Opportunities – With targets for desalination remaining aggressive in the 12th FYP, China Water Risk reviews China’s desalination market – its past & future as desalination is expected to become more profitable given rising water tariffs
• 2013-2014 Key Water Policies Review – Haven’t been following China’s Three Red Lines strategy to protect water? Given the war on pollution, check out our summary of key water policies from 2013 to 2014

Climate Change

• Climate Risks: Are We Ready? – Climate change is high on the global agenda, especially with COP 21 at the end of this year and yet we still face major stumbling blocks. See CWR’s key takeaways from various 2014 climate conferences from climate tools, regional resiliency plans, legacy issues to limited climate funding
• China: Gaps in Rainy Day Funding – Given increasing economic losses & negative impacts on food production due to extreme weather, China Water Risk’s Hu highlights gaps in flood control investment and expands on how the Chinese government expects to finance rainy days ahead

Other

• 2014 Investments in Chinese Waters -With the government encouraging public & private sector water spend, check out investments in 2014 from agriculture, wastewater, water infrastructure, drinking water to Israeli cleantech
• China Water Investments: 3 Thoughts – Investing in the water sector looks attractive with the Chinese government & consumers wanting water tariff hikes. Will water supply or wastewater treatment be the larger market? Debra Tan shares some on-ground views distilled from recent conversations
• Consumers Willing to Pay More for Water – Lu Shuping, President of Xylem China, shares key findings of a survey of six Tier 1 & 2 cities. Do consumers understand China’s water crisis? Are they ready pay more for safe drinking water?
• Water: Moving Out of Silos – As part of CLSA’s latest ESG in China report: “Mopping-up”, China Water Risk’s Debra Tan was interviewed on all things water: from water & coal to textiles, food & government policies
• Can Cities Meet Increasing Water Demands – Nitin Dani and Georgina Glanfield from Green Initiatives Shanghai share their thoughts on how Chinese cities can ensure water security. Can the public play a role?
• Water-Energy Nexus – for more on the water-energy nexus