From black cloud to green gold: turning Egypt's rice residues into energy

Half a million citizens living in Cairo, North Africa's largest metropolis with 15 million inhabitants, will develop potentially fatal lung diseases and cancers in the next 5–25 years as a result of this year's "black cloud." Each fall, after the rice harvest, farmers south of the capital burn hundreds of thousands of tonnes of rice husks in the open air, resulting in a cloud of thick smoke that drifts up north to the city. The pollution is so tangible that hundreds of Cairenes suffer from respiratory diseases including asthma and bronchitis. And it’s not getting any better: this year’s black-cloud season saw the highest recorded levels of nitrogen dioxide (NO2) and carbon monoxide (CO) since the phenomenon began.

No surprise then that the Ministry of State for Environmental Affairs, established in 1997 and long-considered one of the most toothless arms of government, has come under heavy criticism for its failure to prevent the annual appearance of the black cloud, which officials blame squarely on rice farmers.

Egypt has become one of the world’s top rice producers in recent years, with a total area under cultivation climbing more than 30% in the past four years. In 2002-03 alone, Egyptian farmers milled more than 3.8 million metric tons of rice. And more rice, of course, means more rice husks and rice straw, which farmers eventually burn to prevent the spread of parasites and to clear up field space.

Almost all of Egypt’s rice is produced in seven Delta governorates. The main producer is Sharqiyah, which cultivates 281,000 feddans of rice per annum, turning out more than one million tons of rice and leaving behind an estimated 858,000 tons of husks and straw. Of that figure, 686,000 tons are burned.

Feedstock for biogas, ethanol, synfuels, electricity
Burning rice husks and straw in the open air means wasting the energy this biomass contains. Because of a lack of appropriate biomass conversion technolgies, Egypt's farmers are throwing away a valuable source of energy. How much exactly?

• Let's assume a product-to-residue ratio of around 1 (this means for each ton of rice produced, 1 ton of husks and straw becomes available; actual ratios differ from study to study - see earlier post)
• Assume that 3/4 of all the residues can be recuperated (this is how much is burned in Egypt)
• Assume an average lower heating value of 15GJ per ton for both types of biomass
• An annual production of 4 million tons in Egypt
• And an average biomass conversion ratio of 35% (this ratio may vary depending on the technology and the type of resulting biofuel - liquid, gaseous or solid).

Then Egypt is looking at a potential of 15,75 Petajoules of bioenergy per year from rice residues. This amount roughly equals 2.58 million barrels of oil. This energy is currently being wasted.

No wonder then that a number of Egyptian researchers and environmentalists have searched for a practical, economical solution to the problem since the turn of the century. Muslim Shaltout, an environment researcher at the Astronomical Research Center in Helwan, who has conducted specific research on Cairo’s black cloud, says there could be better means of disposing of agricultural waste:
bioenergy :: biofuels :: energy :: sustainability :: rice :: residues :: biomass :: pollution :: bioconversion :: cellulosic :: Egypt ::

“Burning solid and agricultural waste is economically and environmentally illogical. Egypt is one of the poorest countries when it comes to biomass energy [created from vegetative waste], as its cultivated area represents only 4% of the country’s total area,” he says, “so burning rice husks is considered waste of a potential renewable source of energy — biomass energy. [...] agricultural and forest waste [can be treated by dry] distillation [pyrolysis], turning it into light and heavy oils that can be used for a variety of purposes. The solid matter that comes out of this process is considered the best type of organic compost.”

The Minister of State for the Environment has welcomed the idea of manufacturing oil and compost from agricultural waste, but there are many different bioconversion options. Earlier, we referred to German scientists who have developed a highly efficient circulating fluidized bed combustion system specifically for rice residues, that allows efficient combustion for power generation (earlier post). In world's first, a US ethanol producer has just started harvesting rice straw for the cellulose it contains. The rice residues will feature as the feedstock for America's first cellulosic ethanol plant.

Another option is using the biomass for the production of biogas. A recent EEAA report suggests that the Egyptian ministry has concluded a deal with a Chinese research center to develop two facilities to do just that: to convert rice husks into biogas for domestic use by rural residents.

So if the problem is with the farmers and the solutions are so simple, then why does Cairo's black cloud makes its reappearance each year? In public statements, Minister of State for Environmental Affairs Maged George has blamed municipal authorities for not monitoring the burning ritual. And while he inked a deal with the Ministry of Agriculture to collaborate in collecting 125,000 tons of rice husks from farmers to keep them from burning the waste this fall, even that modest target was not met.

The problem? Bureaucratic inaction, insiders say.

A bureaucratic black cloud
Farmers may bear the brunt of criticism, but the capital’s industrial zones are not exactly squeaky clean. Shubra El-Kheima’s spinning and weaving factories to the north of Cairo have long been a source of air pollution as the wind carries their emissions into the megalopolis.

In the 1960s, cement factories opened in the southern suburb of Helwan, adding dust to the atmospheric mix. During the 1990s, airborne cement dust levels exceeded 32 times the recommended limits set by the World Health Organization (WHO). An EEAA report on air pollution admits that “efforts to accelerate the pace of industrialization did not go hand-in-hand with proper environmental planning.”

That’s bureaucrat-speak for, “Oops. Maybe the cement companies are poisoning our citizens.”

El-Hennawy’s study ranks Cairo’s air pollutants as follows: 50% from industrial sources, 35% from vehicular emissions and another 15% (and probably the most acrid) from the burning of agricultural waste. Among the polluters he counted two years ago: 12,600 industrial establishments including 150 large factories; four main power stations; and about 1.6 million vehicles moving through the city streets — figures that rise by as much as 10% annually.

Worse: At least 40% of the 1.93 million (or so) vehicles believed to be on the streets today have older, poorly maintained engines that emit denser pollutants. Worse still: A USAID-sponsored roadside emissions testing program that would have pulled thousands of polluting vehicles off the capital’s streets appears to have become a dead letter since Washington started axing support for infrastructure, environment and health programs three years ago.

EEAA figures differ slightly from El-Hennawy’s and, if anything, they paint a darker picture: In addition to about 12,000 small industrial activities, the EEAA tallies four cement factories, 750 foundries, 70 quarries, 110 rock cutters, 53 pottery kilns, 73 lime stoves, 530 brick factories, 1,206 metallurgical factories, two oil refineries, five power stations and 269 coal processors.

While industry is clearly no angel, El-Hennawy says, it’s clear that factory emissions by themselves haven’t created the black cloud, which manifested itself only in the past decade.

Even before the phenomenon began, the government had taken steps to clear the air with Law 4 of 1994. Among other stipulations, it set limits on industrial and vehicle emissions; prohibited the burning of solid waste except in residential, industrial and agricultural areas; and even banned smoking in public places.

Problem is, the law has never been fully enforced.

In 1999, the EEAA completed the installation of two high-tech networks to monitor air pollution. One network of 20 stations monitors dust and lead particles in Greater Cairo; the second includes 42 monitoring stations in the most-heavily polluted areas throughout Egypt, checking levels of sulfur dioxide, nitrogen oxides, ozone, smoke, carbon monoxide and suspended particulate matter.

In 1999, the Ministry of Petroleum started producing unleaded gas for private cars, and in 2002, the percentage of sulfur in gasoline used by industries and vehicles was reduced to 0.41% from 0.65%. Leaded gasoline is now off the market, as are most lead-based paints. The use of mazout (naptha) as a fuel by bakeries in residential areas has also been banned.

Under the Cairo Air Project, 50 public buses and 55,000 taxis and private vehicles were converted to run on relatively clean-burning natural gas, as have 98% of Cairo’s power plants.

In addition, a USAID-funded project has been working on reducing lead pollution caused by foundries. “Around 100 foundries are located in Shubra El-Kheima, where the wind [from] the north carries the lead particle emissions to Cairo,” says Abdel-Aziz, the Qalyoubeya lead-monitoring project officer. “We were supposed to work on the lead emitting foundries in Fustat — it is the worst heavy-metal pollutant and those factories are the causes of many diseases — but the governor closed down these foundries three years ago, which did not make our job any easier as the foundry grounds were still polluted. The concentration of lead in the soil has reached 65%, which meant that any breeze would scatter this dangerous material all over. We worked on treating these locations as well.”

EEAA statistics from the monitoring network show that air pollution decreased “significantly” from 1999 to 2004, with general pollution reduced across the country by 34%.

There are doubts about the official figures, and not just because of the annual appearance of the black cloud. In his study, El-Hennawy says, “The average daily sulfur dioxide concentration in the air is 170 micrograms per cubic meter. This figure far exceeds the recommended limits set by the WHO to protect public health. As for the black smoke, the average yearly concentration ranges between 65 to 88 micrograms per cubic meter, compared to WHO standards of 40 to 60. Lead concentrations in Cairo’s air range from one to three micrograms per cubic meter, a slight decrease that came about due to the use of unleaded car gas.”

A Costly Cloud
There’s a clear and compelling economic case for curbing environmental pollution across the nation.

“Pollution causes 2,400 cases of early death every year. It results each year in 15,000 new cases of chronic bronchitis, 329,000 cases of pneumonia, eight million asthma attacks and at least 28 million days of reduced or lost productivity,” El-Hennawy says. “The overall cost of air pollution is estimated at around LE 10 billion yearly.”

Other researchers echo his dire prognosis. In an interview with the state-owned daily, Al-Ahram, Salah Hassanein, a professor of environmental studies at Cairo University, predicted that this year’s pollution could cause 500,000 new cases of potentially fatal respiratory problems and cancers in the next 5-25 years, a figure that has since been endorsed by leading epidemiologists.

According to Shaltout’s research, pollutants block up to 40% of solar radiation in certain areas of Cairo. A lack of sunlight can cause serious health problems, especially in children, whose bodies need the sun to convert and use certain vitamins. The causes and effects are clear, but experts agree there is no simple cure for the cloud.

“There is no radical solution to the problem. To end this phenomenon totally and to counter air pollution, we need billions of pounds,” El-Khayal says. “We cannot ask people to stop burning rice husks or agricultural waste if we do not have an alternative. We cannot even ask the municipal authorities to stop them if they have no budgets for that.”

In internal documents, the EEAA has outlined steps the government needs to take to control air pollution: promote the use of clean technologies, encourage technological upgrades of old factories, concentrate industrial activities in new cities and outside residential areas, control the burning of solid waste and find safe ways to dispose of and recycle it, and promote the use of clean fuel like natural gas, wind and solar energy.

Suggestions also include relocating the Helwan factories and the Cairo airport. But even the more logical solutions seem easier said than done.

El-Hennawy has his own ideas, suggesting that the 1994 Environmental Law and, most importantly, its executive regulations, must be reviewed to resolve issues including industrial emissions and traffic regulations. He also suggests that imports of air-polluting vehicles should be banned and that licensing fees for natural-gas powered vehicles be reduced. However pragmatic his suggestions may be, he still has no practical solution for the seasonal black cloud.

“Burning rice husks should be organized and open-air burning of rubbish prohibited, with penalties for violators,” he says. Until something is done, Cairenes can only hold their collective breath and wait for the smoke to clear.