Green Landfills: From Waste to Energy


A pre-dug CRA pipe that will eventually be covered with garbage as it piles higher. This will enable the company to suck out the methane gas produced by the garbage. (Photo: Grace Protopapas)

It is the same story over and over again: landfills are bad, they are dirty, they are noisy, and the smell could knock out even a skunk. With almost 15,000 tonnes of waste sent to landfills every day from the Buenos Aires metropolitan area, it is not unfair to say that landfills are the pit of society. But while they are most definitely smelly and unattractive, what most people do not know is that they are also green, and getting greener.

“We are working very hard to manage the garbage,” says Marcelo Vechiati, the engineer in charge of CRA operations at the Ensenada landfill. “It’s easy to complain but when people come here and see the landfill, it changes their opinion.”

Vechiati works for Conestoga-Rovers & Associates (CRA) at the Ensenada landfill just outside of La Plata. The landfill receives 700 tonnes of garbage a day from both La Plata and the surrounding area.

Owned by the State Society for Ecological Co-ordination of the Metropolitan Area (CEAMSE), Ensenada is a very advanced landfill with not only proper treatment of the garbage itself but also the green technology of flaring methane gas into CO2.

Flaring, as the process is called, is a popular way of dealing with the very toxic methane gas that is constantly leaking from landfills. Numerous sites across Argentina have built flares.

Besides flaring, there is also the even greener option of using the gas for creating energy and finally, the greenest of all, is the new technology of separating, drying, and burning the garbage to create fuel. However, the process of burning garbage remains very controversial.

Flaring Methane Gas

Flaring is the environmentally-conscious process of transforming the toxic methane gas that is constantly leaking out of landfills, into carbon dioxide (CO2). Although still not good for the environment, in terms of its global warming potential, CO2 is 21 times less potent than methane.

“Methane is more potent than CO2,” says the US Environmental Protection Agency (EPA), “When these emissions are compared on an equivalent scale, which is referred to as greenhouse gas equivalents, methane contributes more to global warming.”  The EPA has done numerous studies looking at the flaring of garbage.

Vechiati explains that the projects at Ensenada and González Catán are compliant with the Kyoto Protocol. Although the protocol seems to have slipped into that awkward zone of accepted failure, and no one really wants to talk about it, some companies are still trying to reduce their greenhouse gas emissions.

“CEAMSE wanted to do something related to the environment and they saw the potential of the bio-gas generated by the landfill,” says Vechiati. “So in 2005 they opened a tender to get different proposals to do something with the biogas; CRA won the tender and became a partner of CEAMSE.”

A meter shows how much gas passes through the flare each hour. (Photo: Grace Protopapas)

Canadian company CRA organised the technology to be built at both CEAMSE’s Ensenada and González Catán landfill sites. Now the flaring process is burning more than 3,000 cubic metres of gas per hour.

The methane gas is sucked up from the modules, the hills filled with garbage, through vertical wells that are 16-18 metres deep. The wells pull the methane gas up into a giant tube, which transports the gas all the way across the landfill onto the flaring site.

The gas arrives at the flaring site through a well that is deep under ground in order to naturally drain as much moisture as possible. It is then sent to a moisture filter to get rid of any that made it past the draining system, as the gas must be very dry.

The gas then travels through another tube, which blasts it into the flare. Tubes at the bottom of the 12-metre tall flare release propane which reacts with the methane and oxygen in a combustion process that changes the molecules and creates CO2. The CO2 is then released into the atmosphere.

The flare at Ensenada is currently not at full capacity due to construction issues. But Vechiati hopes it will be back to burning close to 6,000 cubic metres of gas per hour in a few months.

Across Argentina numerous landfills have employed flaring, including the landfills in Villa Domínico and Olavarria in Buenos Aires, Salta, Puente Gallego in Rosario, AESA in Misiones, and Las Heras in Mendoza. However, regulations set down by the Kyoto protocol are not internationally binding or imposed by the Argentine government. Whether or not to do something about the environment is up to the owner of the landfill.

Also, although it is a friendlier gas, CO2 emissions are a big problem in Argentina. According to World Bank data from 2008, the average Argentine created five cubic metres of CO2 per year, which was almost double the amount of the rest of Latin America combined, which comes in at 2.8 cubic metres per capita. The amount of CO2 emissions has been on the rise in Argentina, spiking from 4.1 to 4.8 cubic metres in just three years. Latin America’s is also rising but has only gone up 0.3 cubic metres in the same amount of time.

Over at Norte III, CEAMSE’s other landfill, three different companies are working on flaring. They are also using the even cleaner technology of energy generation from methane.

From Gas to Energy 

Energy generation is similar to the flaring of methane gas in that it is using the naturally emitted gas from garbage in landfills for an environmentally-friendly purpose.

A pipe takes the methane from the landfill to the flare site. (Photo: Grace Protopapas)

At Norte III, Multi Ambiente is the company in charge of turning the gas into energy. Norte III, just outside the city in San Martín, is by far the largest of CEAMSE’s sites with around 15,000 tonnes of garbage coming in everyday from the city of Buenos Aires alone, as well as receiving garbage from numerous other cities.

“With the large economic global crisis, and the reduction in the CER [Certified Emissions Reactions] prices, we are rethinking and focusing on energy generation,” says Leonardo Maseiras, the sub-manager of operations at CEAMSE. “This is why we have running in Norte III a 5MW/h plant and are constructing one that will create 10 MW/h.”

CERs are what CRA and CEAMSE are being paid to create. When they change the methane gas into CO2 they have made a CER, which they then sell to make a profit. However, with the global economic crisis the price for CERs has plummeted, making the expense to create them more than they are worth. Turning to energy generation not only guarantees a profit but is also better for the environment. Various other landfills sites across Argentina are also looking into energy generation instead of flaring.

The use of methane to create energy is a similar process to the flaring of methane. The gas is collected in tubes that are drilled vertically into the modules. With giant vacuums it is sucked out of the hill and carried through tubes to the energy conversion site.

There the gas turns massive turbines that create energy. That energy is then collected and transferred to state-owned energy company Enarsa.

“All the power lines in Argentina are connected,” says the president of Insaap Miguel Suarez, “All the lines are owned by Enarsa. This is a national government agency. It doesn’t matter where you are in Argentina, you are getting the same energy.”

Insaap is the company in charge of contracting the green projects at CEAMSE’s landfills. They controlled the actual building of the flare at Ensenada. They are also looking into waste-to-energy technology that incinerates the garbage itself.

The Tyrannosaurus

Enter the Tyrannosaurus. Although not literally a giant scaly dinosaur, the machine in question has the power to do some serious damage; to garbage that is.

Developed in Finland by BMH Technology, the Tyrannosaurus is the name of the actual machine that shreds the garbage. The shredder is part of a massive assembly line that takes municipal solid waste (MSW) and turns it into solid recovered fuel (SRF) which can then be burned to create energy.

Through various filters and magnets all liquid waste, metals, and organic waste are pulled out of the MSW for compost and recycling. The garbage left is then dried and sent through the Tyrannosaurus, which shreds what is left making SRF.

“The idea of the project is to generate fuel with garbage. It separates the inorganic and organic parts and uses the combustible part to make fuel,” says Suarez.

The end product is “highly-calorific fluff” that is ideal for burning to create energy, either mixed with traditional solid fuels like wood, peat and coal or used alone. Emissions of greenhouse gases are seriously minimised due to the high-temperature burning of the SRFs. This option makes garbage burning one of the most environmentally friendly ways of dealing with a city’s waste.

“This is something CEAMSE would like to do in Norte III but we are only just studying it, it is extremely expensive,” says Suarez.

Besides Norte III the National Institute of Industrial Technology (INTI) is also looking into something similar for the province of Mendoza’s landfills. They plan on constructing a prototype, which will burn 10 tonnes of garbage a day. The price tag for the prototype has been budgeted at $30 million.

The Province of San Juan is also trying to be the first province to burn garbage by participating in a competition held by the National Ministry of Science and Technology. If their project is picked, a $36 million power plant that is fuelled by waste will be built.

The Politics

Part of the problem with developing green technology at landfills in Argentina is the unknown life expectancy of a site. In order to get funding for flaring, energy conversion, and shredding for incineration projects like the Tyrannosaurus, they need long-term proposals. But like many other things in Argentina, the landfill sites are often subject to political tug of war.

The other problem is the huge controversy surrounding what is essentially the burning of garbage.

The Citizens Coalition Against Incineration was formed in 1995 to protest the original plan to simply burn the garbage with no sorting whatsoever.

The flare tower burns the carbon-dioxide which while still polluting is 21 times less dangerous for the environment than burning methane. (Photo: Grace Protopapas)

“The incineration of waste creates new environmental and health problems, discourages the minimisation of waste generation, and is incompatible with programs for recovery, recycling, and composting,” writes the coalition on their website.

Although many people still balk at the idea of burning garbage today, BMH claims that the burning of SRF is much more environmentally friendly. The gas created from the burning can be used to turn massive turbines creating energy. When the entire process is complete the only thing left is organic waste for compost, metals that can be melted down and reused, and energy from the burning of the SRF. All of this is done with fewer greenhouse gases escaping.

For now, landfills in Argentina are focusing on what they can do: flaring methane gas to create CO2 and converting methane into energy. Despite being covered in plastics, left over food, and shiny metals, they are getting greener.

“People don’t like the idea of landfills but even if you know nothing about the environment you can see that we are environmental cleaners, not environmental polluters,” says Vechiati. “After all, where else are you going to put the garbage?”

Do Argentines think these initiatives will help solve the rubbish problem? Click here to find out.

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