Improved technologies to combat air pollution

Published: April 17, 2016 19:22:18 | Updated: October 22, 2017 19:51:51

Air pollution is a major issue around the world. It kills seven million people annually-one in every eight people that die around the world. And, of course, air pollution is a well-known and much-complained-about fact in Bangladesh. Few major global cities suffer from air pollution worse than Dhaka. During the dry season, when dust is especially bad, pollution levels can reach up to 16 times higher than the World Health Organisation's air quality guideline.

Outdoor air pollution kills 14,000 of Dhaka city's residents each year-and it's not even the most damaging air pollution plaguing the country. Household air pollution caused by cooking indoors over open fires is the most deadly environmental problem in the world. The long-term health effects-which can include lung cancer, stroke, and heart disease-can be as bad as smoking two packs of cigarettes a day. Nearly nine out of every 10 households in Bangladesh use wood and other biofuels to cook inside, and the resulting household air pollution causes up to 150,000 deaths annually.

Of course, we would like to fix both indoor and outdoor air pollution, along with the many other challenges that still Bangladesh faces. But resources are scarce, and we know that not all problems will be addressed immediately. So to which of the air pollution problems should Bangladesh focus its attention first? Or are there other and more urgent issues where we could do even more good first?

Answering this question requires us to look not at the problem at hand, but at the available solutions. And it also requires us to look at how much each solution will cost, and how much good it will achieve. This is exactly the information that a new project, Bangladesh Priorities, will help provide. We work with dozens of teams of local and international expert economists. Each team studies the costs and benefits of solutions to issues like air pollution, along with maternal health, education, infrastructure needs, and many others. In a partnership with Copenhagen Consensus and BRAC, we aim to help Bangladesh discover where we can do the most good for every taka spent toward solving the country's most pressing problems.

When it comes to reducing deadly air pollution inside the home, our new research examines two solutions: People could replace their traditional cookstoves with smarter ones, which burn biofuels much cleaner and emit less pollution, or they could instead use liquefied petroleum gas (LPG) stoves, which replace biofuels entirely and burn even cleaner.

 The first option, an improved biomass cookstove, turns out to be most cost-effective. The stove is enclosed, which helps maintain heat better than a traditional stove and protects fuel sources from the wind. This helps burn biofuels much more cleanly. Improved stoves also transfer heat to cooking pots more efficiently, so they save on fuel costs.

An improved stove with two burners and a chimney that will last for three years costs about Tk 1,000 per year in Bangladesh. The cost covers both the stove itself, which has to be replaced every third year, as well as some maintenance. And almost one-third of the cost helps promote awareness of the opportunity in communities.

Thirty million Bangladeshi households use traditional stoves. If they all switched to improved cookstoves, the pollution reduction would save more than 33,000 lives each year. Each of these people would live an additional 28 years on average. Since this benefit is spread over 30 million households, the benefit for each is about Tk 2,600 each year. Moreover, fewer sick days add an additional benefit of Tk 260.

The improved stoves cook faster and require less fuel, so each day they also lower fuel collection time by half and save 15 minutes in cooking time. Those benefits are worth another Tk 2,000. For each Tk 1,000 in spending on a better cookstove, a family will get almost Tk 5,000 in health and time-savings benefits. Every taka spent will do 5.0 takas of good.

Improved stoves can take a big step to improve household air quality, but they promise to save "only" 33,000 of 150,000 annual deaths. Most of the problem of household air pollution would still remain. So the analysis looked at a second option that could reduce overall household pollution much more.

LPG burns very cleanly-almost like an electric stove. If every Bangladeshi household adopted these stoves, it would save 91,000 lives, a total value of Tk 218 billion (Tk 21,800 crore), or Tk 7,300 per household. Each household would avoid about 700 takas of disease, cooking time would drop by 40 minutes, and there would be no need to spend any time collecting fuel. The net worth of these benefits would be Tk 5,200 for each family.

But an LPG stove and fuels cost a great deal more than an improved biomass cookstove. The price is about Tk 10,000 per year, plus Tk 2,000 more to buy fuel. In total, you would pay about Tk 12,000 for about 12,000 in benefits. So spending on LPG stoves would not be a loss, but it would yield only one taka in benefits for each taka spent.

This shows that sometimes the best option can be an enemy of the good. The cheapest way to improve the quality of indoor air is to get widespread investment in improved biomass cookstoves.  Despite helping less overall, this cheaper option can be a much better way to help per taka spent. In the long term, however, more expensive options can become solutions. As Bangladesh moves towards middle-income status, higher LPG adoption can become more alluring

THE POLLUTING KILNS: When it comes to air pollution outdoors, the challenge is often much more difficult to address. Rather than having one source of pollution for one family, as with cookstoves indoors, there are usually many sources that emit pollution outside, and it can be costly to clean up each one. Dhaka presents a unique opportunity, however, because a great deal of its air pollution comes from just one source: kilns used to make bricks for the construction industry.

More than 1,000 kilns manufacture 4.0 billion bricks each year in Dhaka, and they are responsible for about 40 per cent of the city's fine-particulate air pollution-which causes an estimated 2,000 deaths each year. Technologies to improve these kilns, however, promise great benefits-both for private owners and for the environment and society at large.

Most manufacturers traditionally use fixed-chimney kilns. These are energy-inefficient, emit a great deal of pollution, and mostly burn dirty fuels.

To make brick-making kilns cleaner and more efficient, they can either be replaced with entirely new ones, or be retrofitted. Our new research examines multiple options that range from a simple upgrade into "improved zigzag" kilns, all the way to new and cutting-edge Hybrid Hoffman kilns.

 A Hybrid Hoffman kiln uses top-of-the-line technology and promises very large overall benefits. But a single kiln costs Tk 160 million (Tk 16 crore). A retrofit of an existing fixed-chimney kiln into an improved zigzag kiln is 40 times cheaper. This upgrade into a zigzag kiln does about 8.0 takas of good for each taka spent, and it turns out to be the most cost-effective strategy.

Retrofitting a fixed-chimney kiln into a zigzag kiln costs Tk 4 million (Tk 40 lakh) and takes about three months. The better technology heats bricks more efficiently and evenly because hot air blows over bricks in a zigzag pattern. And zigzag kilns reduce fuel consumption by one-fifth, which is one reason that an owner can pay back his or her investment in less than four years.

Adopting zigzag kilns across Dhaka would reduce air pollution from brick-making kilns by 40 per cent, saving more than 800 lives per year. This would cost about Tk 408 million (Tk 40.8 crore) annually over the operating life of the kilns. But the benefits would be quite large. Annual health benefits alone would equal Tk 1.7 billion (Tk 170 crore).

The reduction in carbon emissions would be worth another Tk 80 million (Tk 8.0 crore). Private kiln operators would also get a number of benefits, including higher quality bricks and lower energy consumption. In total, the benefits to investors and owners will be Tk 1.4 billion (Tk 140 crore).

As Bangladesh becomes richer and solves many of its other challenges, adopting the cutting-edge technology rather than simple retrofits could help achieve the greatest possible environmental benefits. Replacing all kilns in the capital with Hybrid Hoffman kilns, for instance, could yield even larger overall benefits. The health benefits would be worth Tk 2.5 billion (Tk 250 crore) per year, and lower levels of carbon emissions would be worth Tk 161 million (Tk 16.1 crore). Business owners would also benefit by Tk 8.6 billion (Tk 860 crore), thanks to more efficient brick production and improved quality of bricks.

However, the cost would be very high-Tk 3.3 billion (Tk 330 crore) annually. Each taka spent toward this end would do a little more than 3 takas of good, which is respectable, but not nearly as great as the 8 takas of good that retrofitting to improved zigzag kilns gives.

Whether it comes to the outdoor environment or inside homes across Bangladesh, the need to reduce air pollution may seem obvious. But using scarce resources to fight air pollution means less funding will be available from the national budget, international donors, or private citizens for other proposals that can do good.

Dr. Bjorn Lomborg is president of the Copenhagen Consensus Center,  ranking the smartest solutions to the world's biggest problems by cost-benefit

He was named one of the world's 100 most influential people by Time Magazine


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