Macaúbas Waste to Energy

Brazil’s Iron Quadrangle: Where Rivers Led to Gold

Brazil’s Iron Quadrangle is a region shaped by discovery. Early explorers followed clear mountain streams, their waters glinting with mineral deposits, in search of the legendary Sabarabuçu: the “mountain of gold.” While tracing these waterways, they uncovered rich deposits that sparked Brazil’s gold rush.

As the gold rush faded, the region evolved. While mining remains a key economic activity today, it is now largely driven by iron ore production. 

Yet traces of the past are still visible. Historic mining towns like Sabará and the UNESCO-listed Ouro Preto offer a window into a bygone era, where colonial buildings, cobblestone streets, and Baroque churches adorned with intricate gold embellishments reflect the scale of that prosperity. The legacy extends to the region’s modern hub, Belo Horizonte, where an internationally acclaimed culinary scene reflects the diverse influences brought by the influx of people during the gold rush. The city is known as the capital of pão de queijo, Brazil’s staple cheese bread, developed during this time through the ingenuity of enslaved Africans brought to the region to work in the mines.

In the Espinhaço Mountains, where the story began, those same rivers still pulse through dramatic rock formations. But instead of guiding explorers, they now draw visitors with cascading waterfalls, crystal-clear waters, and rugged landscapes that invite hiking, canyoning, and immersion in the region’s natural beauty.

When Hydro Can’t Meet Demand, Fossil Fuels Fill the Gap

Today, the towns and rivers that played a pivotal role in the region’s development are showing the effects of increasing pressure. A long history of extraction, combined with rapid urban expansion, is placing growing demands on local environments and systems.

As cities and populations have expanded, electricity demand has surged. The country’s power generation has more than doubled in recent decades to keep pace.

That growing demand is straining an energy system heavily dependent on rivers and consistent water levels. Hydropower is the primary source of Brazil’s electricity, and the rivers in this state support more hydropower plants than anywhere else in the country, making them critical to energy security and economic stability.

Climate change is intensifying these challenges. More frequent and prolonged droughts reduce water availability, while extreme rainfall events increase the risk of flooding, infrastructure damage, and sediment buildup. These climate impacts can affect hydropower performance. 

As hydropower becomes less reliable and demand continues to rise, the gap is increasingly filled by fossil fuel power plants.

A Growing Waste Problem = A Growing Climate Problem

Pressure on the region isn’t limited to energy systems. As the region has grown, so too has the volume of waste it produces.

The Macaúbas landfill, which serves Sabará and 24 surrounding cities, receives around 3,000 metric tons of waste each day — roughly the equivalent of more than 200 garbage trucks.

Across Brazil, around 45% of urban waste is organic, such as food scraps and garden waste. This pattern is reflected in the waste stream reaching the Macaúbas landfill. In one nearby municipality whose waste is sent to Macaúbas, nearly two-thirds of organic material is still discarded with general waste.

Tourism adds to this broader waste stream. Food is a central part of travel, especially in places known for their gastronomic identity, like Belo Horizonte. Many parts of the tourism experience, from restaurants to local markets and festivals, produce surplus food that ends up in the trash. Across Brazil, tourism generates over 130,000 metric tons of solid waste each year, including food waste, plastic packaging, and other disposable items used by visitors.

When organic waste, including food, is sent to landfills, it breaks down and releases methane—a greenhouse gas that traps 28 times more heat in the atmosphere than carbon dioxide over a 100-year period. In Brazil, the waste sector is the second-largest source of methane emissions, largely due to solid waste disposed of in landfills. Estimates suggest the Macaúbas landfill could generate methane emissions equivalent to up to 950,000 metric tons of CO₂ per year, roughly equal to the annual emissions of 221,000 gas-powered vehicles. 

Beyond its climate impact, methane also poses risks to nearby communities. It is highly flammable and releases foul-smelling compounds that degrade air quality and create health hazards.

With populations rising and waste volumes increasing, the challenge is only expected to grow. Without changes to how waste is managed, municipal solid waste in Brazil is projected to increase nearly 45% by 2050, underscoring the urgency of improved waste and methane management.