China is slowly changing its energy mix from coal fuel to natural gas, but researchers from Princeton University in the US say using coal-based synthetic gas, known as SNG, would increase carbon emissions and water demand.

The researchers’ investigations into the environmental impacts of a shift managed by 2020 suggest the move would generally benefit China’s air, carbon and water, provided instances of methane leakage can be controlled.

Dr Yue Qin, first author of the study and postdoctoral scholar at the University of California, said that “assessing air quality, carbon emissions, and water scarcity impact is crucial to capturing potential co-benefits while avoiding unintended consequences”.

The study’s principle investigator, professor Denise Mauzerall, said that while the paper focuses on China, “its general conclusions are widely applicable”.

China accounts for more than half of global coal consumption, and natural gas makes up only 6 percent of the country’s primary energy use. By comparison, the global average proportion of natural gas consumption is 16 percent.

Aside from using coal-based synthetic gas, the researchers conclude that replacing coal with natural gas can substantially cut CO₂ emissions as well as water use.

“Ultimately, a full transition away from carbon-based fuels will be necessary to address climate change. In other research we have found that renewable energy provides the largest co-benefits for air quality, carbon mitigation, and reduced water consumption of any known energy sources,” professor Mauzerall said.

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The project, which began in April this year and is expected to take several decades to complete, is a state-run infrastructure programme to move 44.8 billion cubic metres of fresh water each year from the Yangtze River to China’s arid and industrialised northern territories via three canal systems.

The central system has so far been used to replenish several northern rivers with around 870 million cubic litres to fight water scarcity and environmental deterioration across the region. This route has alleviated water shortage in provinces and cities along its course, ensuring water users receive adequate water supply.

So far, the project has channeled 467 million cubic litres to Henan Province, along with 351 million cubic litres to Hebei Province and 47 million cubic litres to Tianjin Municipality.

Water scarcity has been identified as a problem affecting three rivers including the Baihe, Qinghe and Tuotuo, all of which have drawn supply from the diversion.

“As a major infrastructure project of national strategic importance, [the project] has not only guaranteed water supply in northern China, but also brought about huge ecological benefits,” the report said.

It added that in Henan Province, the project has replenished 18 rivers in 12 cities, including Zhengzhou, Nanyang and Jiaozuo, bringing “greater volumes of water in wetlands and reservoirs and improved water quality in the area”.

Official government figures estimate that the Xushui District grew by around 430,000 square metres since the project began, and that subsequently, the level of groundwater has risen by an average of 0.96 metres. The report concluded that as of 17 June, the central route has reach total inflows of 15 billion cubic metres at a rate of around 384 cubic metres per second.

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Above all, I believe in strengthening the existing member network by improving the visibility of German Water Partnership in Germany and abroad and engaging new members to join the GWP-network. The launching of our new Website in mid-2018 is a first step in that direction with many more to come. Furthermore, we will strengthen existing cooperations and partnerships with ministries and partner organizations.

In many developing countries, particularly those within Africa, there is a disconnect between a lack of advancement in infrastructure and an advancement in smart technology, between which an opportunity presents itself for digital infrastructure to leapfrog developed nations. How is GWP working to realise the potential in this space?

GWP has been actively driving the agenda on digitalization in the water sector through our Working Group WATER 4.0 – our members have been actively embracing the opportunities arising from digitalization by developing concepts custom made for developing countries based on smart technology. With joint booths on the international water exhibitions and our own conference brand GWP-Day we actively showcase the German know-how and
expertise in WATER 4.0 worldwide and continue to provide a platform for establishing new digital solutions.

What are you doing as general manager to encourage more young professionals to enter the water sector?

As the network representing the internationally active German water sector we closely work together with Germany’s technical universities, research and training institutes. We are also participating in international programs such as the ASApreneurs-program and thus offer young students the chance to work on water related projects abroad. This year the GWPconferences in Sambia and Colombia will be supported by two such young professionals. These conferences aim at showcasing solutions for water related challenges and bring experts from Germany together with their counterparts abroad.

What signifcance do you place on the influence of global cities as places facing enormous demand for sophisticated and sustainable water supply over the coming thirty years?

I see an extremely high significance with a rapidly growing need for circular concepts and re-use solutions, which can be provided by the extensive German know-how in environmental technology. The focus on cities guided by the SDG-Agenda and embracing the opportunities of digitalization will be a core component of the next Blue Planet – Berlin Water Dialogues on 22nd October 2018 that is being coorganzied by GWP.

China is Germany’s biggest private sector competitor in water. How do you think German water companies ought to manage price competition with China?

The German water sector has to concentrate on its core competences: cutting edge research and development paired with excellent engineering. GWP aims to further foster an international understanding that truly sustainable and high quality technologies with a long life-cycle and exceptional efficiency have their price. But German quality goes beyond manufacturing as it involves proper maintenance and service, which can only be provided by excellent schooling and TVET. Germany’s excellence in engineering paired with its excellence in schooling will – proven by sustainable and more efficient solutions – enable German companies to manage future competition.

Are there aspects to the GWP’s relationship with the five German ministries it works with that you wish to see improved and how do you intend to achieve this?

Firstly I can proudly state that the relationship with our five German partner ministries has been very positive, with close communication and cooperation on a multitude of levels. Our common goals have seen a renewed push with the specific focus on Africa and water related issues framed in the coalition agreement of the new German government in spring 2018. Thus, GWP has offered to play a more active role in cooperation on development issues with the Federal Ministry for Economic Development (BMZ). Beyond this newly defined focus GWP will continue to closely work together with all its Federal Partner Ministries regarding their initiatives on export of German expertise and environmental technology in the water sector. Especially the close cooperation with the Federal Ministry for the Environment (BMU) will be continued to support the fulfillment of Germany’s international commitments made with regard to sustainable water management and
environmental protection.

What do you believe the future will hold for the German Water Partnership?

The future holds great opportunities for the German water sector and beyond. Germany has shown for more than a hundred years how water management can be accomplished by fulfilling highest standards. Besides wasteful use of water and inefficient water management, climate change further increases the negative effects on available water resources. Thus, the global community is increasingly aware of the necessary changes needed to sustainably manage dwindling resources. German technology provides truly sustainable solutions to integrated water resource management which can only be achieved
by technological approaches with a long life cycle and the necessary sophistication to tackle both rural as well as complicated mega-city water challenges of today and a demanding future. One key with regard to finding successful solutions for the future certainly is an eye-to-eye level cooperation between partners in Germany and abroad to also adapt concepts to thelocal needs of each country.

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Why Asian cities are adopting and scaling sludge-to-energy systems. By Aditi Sahay

Each year China’s cities must absorb 10 million people, who excrete an extra 1.5 million kilogrammes of faecal matter and an additional 3 million litres of urine. As urbanites flush away their biological waste, requiring treatment of three times more wastewater in 2016 (54.2 billion m3) than in 2007, the country’s 4,000 urban wastewater plants struggle to cope with the pressure.

Many falter. The cities often lack budgets, time, data, and skilled staff to properly treat human waste. But even those plants that do get left with large volumes of a messy by-product: 40 million tonnes of slurry, a toxic cocktail known as sludge.

That amount marked a 16 percent increase in sludge over the previous year, putting China’s nearby aquifers, food and soil increasingly at risk and posing an urban health threat on a par with smog.

Beijing’s leaders decreed cleaning it up. But that’s easier said than done. Sludge treatment is both expensive and energy intensive, costing plants US$36-81 per tonne while devouring a third of municipal power.

For all these reasons, a Tsinghua University study found that less than 20 percent of sludge even gets properly treated. Most is illegally dumped, put in landfills, burnt, or spread out as heavy metal- and pesticide-laden fertiliser, whereupon it leaches into water bodies.

But the combination of mandates, technology transfers, and economic incentives is changing all this, as a handful of pioneering urban treatment plants convert their toxic liability into a clean asset: biofuel.

“Dumping the sludge was a much cheaper way of dealing with it than treating,” says Zhong Lijin, an expert at the Beijing office of the World Resources Institute (WRI), a global research organisation headquartered in Washington DC. But now “China is in a transitional stage of development, and needs to think of sustainable sludge treatment methods.”

Converting sludge into clean energy starts by breaking down the slurry. Thermal hydrolysis combines the high-pressure boiling of waste or sludge with rapid decompression. Anaerobic digestion harnesses microorganisms to break down biodegradable material in the absence of oxygen.

Much of the end product can–with political will, tools and incentives–be recaptured as a gas, liquid or solid fuel. These clean biofuels can be used to generate electricity to run the plant itself, used directly as fuel to produce heat for operating the system or be further processed into transport fuels. Another sterile by-product of treatment, biochar, can be used as a soil enhancement to grow trees on landfill sites that help lower temperatures, capture atmospheric carbon, and improve air quality.

Such an approach may not work everywhere. But in China’s Hubei province, the city of Xiangyang exemplifies the combined push-pull to develop clean infrastructure with public and private investment, as that city has pioneered innovative sludge treatment solutions.

“The Chinese government requires that each city should solve the problem of sludge pollution in the next few years,” says Yue Zhang, former Director General of the Urban Water Management Office at the Chinese Ministry of Housing and Urban-Rural Development. “This is a political requirement that has been incorporated into the assessment index of local officials.”

Success didn’t emerge overnight, or out of nowhere. In the summer of 2015, Zhang was part of a Chinese delegation that visited Blue Plains, in Washington DC to tour the world’s largest advanced wastewater plant. The tour showed how large-scale sludge treatment was not only technically plausible, but made economic sense. The delegation’s new understanding helped Beijing make faster investment decisions and accelerated construction of other plants around China.

“We got to know Blue Plain’s long- term research and demonstration process, and their final choice,” says Zhang. “Also, since it was based on the green, circular, low-carbon economy, this was likely to be a sustainable option.”

There’s a considerable environmental upside of a sludge-to-energy treatment plant. Recovering nutrients from the sludge slashes downstream emissions that might grow from untreated effluent in water bodies. And the natural biogas can be compressed and used as fuel (CNG) reducing carbon emissions by 140,000 tonnes. For the first two months, the Xiangyang plant burned four tonnes of coal per day, but has since been running on its own self-generated clean energy.

To affluent European and North American cities, sludge-to-energy may not feel that ‘new’. But what makes Xiangyang a game-changer is that it shows how, now, even booming cities in the developing world can adapt the technology, and scale up gains to meet climate mitigation targets.

A recent World Resources Institute (WRI) study projects that if all the sludge and kitchen waste produced in Chinese cities is treated by a waste-to-energy approach, 6.6 billion m3 of methane could be produced, which is equal to 9 percent of China’s total methane emissions in 2012. Besides meeting the energy demand of the projects operation, the remaining methane could be used to substitute 4.2 million m3 of gasoline for vehicle use. China’s 13th Five-Year Plan (2016-2020) has the goal of reducing coal consumption from 62 to 58 percent by 2020, and setting up plants will help achieve this target.

Beijing has mandated that 90 percent of urban sludge must be toxic-free by 2020. But regulations alone didn’t tip the scales for Xiangyang’s success; economic forces did. “This project can be duplicated and promoted in other areas,” says Jing Liu, a private investor who backed the project. “The reasons for this are the current advocacy of the circular economy and the fact that many banks are willing to provide support for this type of project. Financing for the sludge-to-energy project is not very difficult.”

For all its benefits, obstacles remain. At the policy level, it remains unclear what is to be done with the rest of the treated sludge. “We have adopted advanced sludge treatment technology, and the treated sludge is of good quality and can be reused,” says Bai Yu of the Beijing Drainage Group, a state-owned company that uses similar technology to treat sludge around the Beijing urban area. “However, national policy is not very clear, which makes it difficult to reuse the treated sludge”.

Chinese officials, worried about the toxic content of treated sludge, have prohibited its use on farmland. But further treatment could pay for itself. “If the national policy becomes more supportive of the sludge-to-energy project,” adds Bai Yu, “the products can be packaged and sold in the market, and more economic benefits can be gained.”

Another challenge is cultural. Traditional engineering and design engineers must learn how to retrofit existing plants to operate using thermal hydrolysis technology. But new courses in China and India are helping teams understand how to treat sludge in ways that reduce emissions.

International groups praise sludge-to-energy treatment processes for combining environmental, urban, agricultural, economic, energy, finance and climate sectors, thus helping advance several SDG goals at once.

“What is really appealing about this project is that it brings together multiple elements of interest,” explains Betsy Otto, Director of WRI’s Global Water Program, including “water management, reduction of greenhouse gases, air pollution and solid waste management. These have gone beyond the classic realm of managing waste, allowing wastewater to become a true resource.”

Worldwide, the UN has estimated the value of human waste converted to fuel at US$9.5 billion. But that’s abstract, on paper. China has taken the spark from Washington DC to Xiangyang, kindled it in other cities around China, and shared it across borders.

India faces similar challenges with water resources and wastewater treatment, and it too has started looking at the feasibility of sludge-to-energy projects. The Qualcomm Foundation has explored policy gaps, hoping India, which lags two decades behind in urbanisation and wastewater management, can learn from China’s experiences to prepare for the forthcoming surge in urban toilet slurry and the need for better sludge management.

As the “output” of Asia’s cities harnesses its own waste as an “input” to fuel treatment operations and grow food, sludge-to-energy unlocks the power of the circular economy for billions who need it most.

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As Xi Jinping ascended to power, he watched, all around him, the equally swift rise of cities.

At his birth in 1953, cities housed just one in nine Chinese; by his marriage in 1987, one in four. By the time he became president, half his country was urbanised across 662 major cities, 100 of them larger than 1 million. From the Chongqing megalopolis (population 30 million) downwards, cities anchor Xi’s ‘Chinese Dream’, his vision of strength, to be reached by marching along ‘the Chinese path’.

Only now that path will not be paved.

While sudden, this dramatic reversal was years in the making. Xi, a former student of chemical engineering at Tsingua University in Beijing, and party leader in Shanghai, confronted an urban paradox. While increasingly in need of supplies, China’s cities were aggressively expelling freshwater.

Indeed, this eviction of water was a sign of urban progress, carried out with the best intentions. To remove an old public health threat–dank, dirty water associated with mould, mud, mildew and miasma–city codes and officials cleaned up, ridding streets and lots of stagnant pools. So across an aggregate 40,000 square kilometres, engineers drained wetlands, tarred rooftops, mounted metal gutters, spread asphalt, poured cement over muddy sidewalks, and sent ‘wastewater’ racing away down enclosed storm sewers.

Never before had so much porous living landscape, been made so impenetrably hard, so fast.

Yet as urban surfaces calcified into a waterproof shell, old problems got worse. City drainage systems were built according to static assumptions, based on past averages; planners did not anticipate or cope with the high-density downpours of a fast-warming climate. In 2013, some 234 cities were flooded due to extreme rainfall–exposing people to lethal risks and eroding billions from assets– while researchers found 641 faced imminent threats of catastrophic urban deluge.

To make matters worse, all that unfiltered urban runoff gushed into already polluted rivers, picking up waste, metals, and microbes and creating a contaminated toxic stew.

As losses mounted, Xi had to act. The old approach would have been to retrofit existing drainage systems, at enormous cost to the treasury and massive disruption of traffic. But there was another option. A porous urban surface could convert an unhealthy liability into a liquid asset which cities could hold back and reuse.

Xi wasn’t the first to embrace urban ‘green infrastructure.’ Officials from Portland and Berlin to Singapore and Sydney have long sought to slow, spread, sink, and store runoff. Infiltration-by-design helps recharge urban aquifers, mitigate floods, and let city surfaces breathe. Cities choose from a menu of cisterns, bioswales, rooftop gardens, retention ponds and permeable pavements, which can reduce half to nearly all runoff. The efforts are known
 as Water-Sensitive Urban Design (WSUD in Australia), Low-Impact Development (LID in North America) or Sustainable Urban Drainage Systems (SUDS in Europe).

Yet most pilots are small, local, piecemeal, and experimental. China had higher ambitions. And jargon like WSUD, LID or SuDS couldn’t compete with the disruptive energy released in 2013 when Xi announced that the People’s Republic would transform its metropolitan areas into what he proclaimed as ‘sponge cities’.

“By regenerating and expanding its own freshwater ecosystems the sponge city allows stormwater to be absorbed by the soil, which also naturally purifies it and stores it as groundwater,” explains Filippo Boselli of Germany’s World Future Council. “This reduces the burden on urban sewage systems, and during extreme weather events, improves the capacity of the city to absorb water and as such decreases the risk of flooding.”

Since 2013, the cadre of sponge cities has doubled to 30, including megacities Beijing, Shanghai and Xinjiang. Early test areas proved able to reduce 85 percent of annual runoff, mitigating floods while purifying, conserving and recharging groundwater for later.

Xi’s decree is unprecedented in scale. His policy has had massive repercussions in and beyond China. His evocative image has rallied domestic and foreign interests around a shared concept. Moreover, Xi has backed up his rhetoric with strict timetables, hard financing structures, clear governance and sharp technical measures.

Yet urban planners and water professionals–struggling to turn a poetic vision into street-level execution–can’t escape the healthy tension between top-down mandates and bottom-up realities.

One primary strain is competing priorities. What exact problem is a sponge city meant to solve: mitigate floods, recycle runoff, or recharge groundwater? For starters, three is not enough. Che Wu from Beijing University’s Department of Civil Engineering and Architecture told a symposium how “the sponge city must [at the same time] achieve the goal of protecting the water environment, water ecology, water resources and water security.”

Combining goals is also too simplistic. Economic challenges, physical contours and political agendas are unique to each city. Wuhan, at the confluence of the Yangtze and Han Rivers, must keep its streets, stadiums and metro stations from flooding, whereas in Baotou, the biggest problem is water scarcity. “The Ministry of Housing and Urban-Rural Development (MoHURD) put forward a guideline for sponge city construction but its contents are limited to the LID measures practised in the USA and other countries,” says Xiaochang C. Wang, an environmental and municipal engineering professor at Xi’an University of Architecture & Technology. “But what a sponge city should be is still an open question.” Unless each city can define ‘sponge’ on its own terms, the nation’s aggregated goal may fall short.

This leads to a related challenge: the mismatch in technical direction. Leaders in sponge cities feel pressure
to write beautiful reports to meet targets set by Beijing
but have no development plans or sketched out blueprint
to construct the desired results. “Negatively speaking, the budget to support sponge city construction from the central government is attractive for all cities,” adds Wang. “On the other hand, academic and engineering societies also pay attention to sponge cities because there are so many things unknown that need investigation and engineering practice.”

Among the unknowns is cost. It is hard for any city to assess the value of becoming an urban sponge. Benefits must take into account social and ecological amenities
that are real and substantial yet nearly impossible to quantify: open space, biodiversity, recreation, trees for shade, cooler temperatures,
and healthier aquatic systems.

Yet immediate costs do add up, and reveal a rising source of tension: money. To prime the pump, Xi
 initially allocated US$50-100 million for each city, funds designed to jump- start investments. The first flow of ‘top-down’ government cash often accounted for more than 20 percent
of each sponge city project budget. But going forward, the central government plans to dry up its portion. That means “cities that plan to become sponge-like should invest by themselves or promote public-private-partnership (PPP) construction,” says Wang. “This is the local bottom up.”

But without an obvious return on investment, few have rushed to do so. PPPs that build a water utility, power station, toll bridge, parking lot, or tunnel can recover costs by collecting Among the unknowns is cost. 
It is hard for any city to assess the value of becoming an urban sponge. Benefits must take into account social and ecological amenities
that are real and substantial yet nearly impossible to quantify: open space, biodiversity, recreation, trees for shade, cooler temperatures,
and healthier aquatic systems.

Yet immediate costs do add up, and reveal a rising source of tension: money. To prime the pump, Xi 
initially allocated US$50-100 million for each city, funds designed to jump- start investments. The first flow of ‘top-down’ government cash often accounted for more than 20 percent
of each sponge city project budget. But going forward, the central government plans to dry up its portion. That means “cities that plan to become sponge-like should invest by themselves or promote public-private-partnership (PPP) construction,” says Wang. “This is the local bottom up.”

But without an obvious return on investment, few have rushed to do so. PPPs that build a water utility, power station, toll bridge, parking lot, or tunnel can recover costs by collecting user fees down the road. Not so with 
a sponge city. Green infrastructure, drainage and bioswales offer banks no immediate or even long-term yield. The social and ecological gains of soft and porous pavement are substantial, but rarely convert into fat profit margins.

For all these obstacles and shortfalls, sponge cities are backed by one powerful force: necessity. Cities can choose where and when and how to become more sponge-like. They
 can re-classify what a sponge city
is. What they cannot do, in China 
or elsewhere, is simply opt out of what remains the most effective and affordable [see cost chart graphic] response to threats from urban floods, water logging, groundwater depletion and polluted runoff.

Early adopters have taken aggressive steps to reduce these escalating risks from below. Yuelai, a new city on the outskirts of Chongqing, is pushing the concept to a holistic level. It has paved streets and walkways with soft, porous, and springy material that sucks down water into aquifers. Parking lots have gardens that
absorb and filter runoff. By retaining water, the damp landscapes help mitigate the urban ‘heat island’ effect, reducing local ground-level temperatures a few degrees.

Zhenjiang city in Jiangsu Province has arguably gone furthest toward
a sponge city, largely because it
 began planning construction before Xi coined the term. “Before it got funds from the central government, the city had a good water-wise city construction plan,” explains Wang. “Therefore, the budget from the central government was not the only financial source but sped up the planned work, and has prevented water logging in the summer of 2016.”

Others point to Wuhan, a city
 of 10 million in central China, as an early mover in making itself softer and more absorbent. “We are very excited to be part of this pioneer project,”
 says Wenmei Ha, Head of Arcadis’ China water management team. The pilot seeks to improve residential quality of life through low-impact development, drainage upgrades, and a reduction in excess runoff, “blending green infrastructure with other flooding control measures to reduce the economic and environmental damage caused by pluvial flooding.”

Hopes for the movement have been tempered by the hard speed bumps of reality. “Frankly speaking, what China has done so far is still insufficient for replicating and scaling either within or outside the country,” comments Wang. “Sponge city is a good concept but it has still a long way to go.” Current levels of funding and policy support may not fuel optimism of an overnight transformation.

Change is gradual. It requires persistence in pursuit of a worthy goal. To that end, Lao Tzu’s old quote may yield fresh insight for resilient cities. “Water is fluid, soft, and yielding. But water will wear away rock, which is rigid and cannot yield. This is another paradox: what is soft is strong.”

The path to soft cities remains steep, hot, rough, and hard. But China has shifted the focus, and offers a bold model for the world. Xi’s national vision may continue to galvanise local plans in a top-down/bottom-up fusion, helping cities outgrow their concrete shell and become, like a sponge, a living organism that half the population may call home.

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