On a boat trip earlier this year, members of the Southeast Environmental Task Force noticed towering piles of fine, black, rock-like material along the banks of the Calumet River in Chicago. The piles were made up of petroleum coke, or “petcoke,” a byproduct of refining tar sands crude, deposited by Koch Companies – one of the largest single sources of funding for conservative organizations in the US.

Last year in Detroit, huge piles of petcoke produced by a Marathon Petroleum Company refinery and owned by Koch Carbon attracted notice after causing swirls of dark clouds to blow across the Detroit River. The Detroit Free Press reported petcoke dust blowing into Detroit homes.

Residents were concerned about the health risks of breathing and being exposed to the dust.

State Rep. Rashida Tlaib wrote about her concern that the black dust was adding to already-elevated levels of air pollution. “The toxic metal vanadium has been found in air samples taken at Hudson Lofts near the piles,” she said. “In high-enough amounts, vanadium can cause respiratory problems… We have extremely high asthma rates in this area and hospitalizations from asthma are clearly linked to air pollution.”

“This is dirtier than the dirtiest fuel,” Michigan Rep. Gary Peters (D) told The Guardian. “We need to know more about this material and the impact on communities.”

In August, the Mayor of Detroit, Dave Bing, ordered the piles being stored along the Detroit River next to the Ambassador Bridge – the busiest international border crossing in North America – to be removed.

The waste piles were reportedly moved to a location in Ohio.

The petcoke along the Calumet River in Chicago is located on land belonging to KCBX, an affiliate of Koch Carbon. When Chicago residents began asking questions about the mounting piles of petcoke, Koch Companies Public Sector LLC spokesman, Paul Baltzer, issued a statement on their site, saying “KCBX Terminals Co. has been handling various bulk products, including petcoke, in Chicago for more than 20 years,” according to Midwest Energy News.

Altogether, about a mile and a half of the shoreline along the Calumet River holds large piles of jet-black petcoke. In one area, the piles rise about five stories high.

Locals report that the amount of petcoke in the area has “skyrocketed” as BP’s Whiting refinery on the border of Illinois and Indiana, just 20 miles from downtown Chicago, nears completion of a $3.8 billion upgrade that will allow it to process more tar sands oil, Energy News reports. Incidentally, the Whiting refinery is one of the largest polluters of the Great Lakes, dumping 20 times more toxic mercury into Lake Michigan than federal regulations allow.

According to Oil Change International, “Petcoke is the coal hiding in North America’s tar sands oil boom.” Petcoke is similar to coal, but dirtier. It has higher carbon emissions than coal, contains over 90 percent carbon, and, because it is considered a refinery byproduct, petcoke carbon emissions “are not included in most assessments of the climate impact of tar sands or conventional oil production and consumption.” Furthermore,

Cheap petcoke helps the coal industry.

• As a refinery byproduct, petcoke is “priced to move”, selling at roughly a 25 percent discount to conventional coal.

• Rising petcoke production associated with tar sands and heavy oil production is helping to make coal fired power generation dirtier and cheaper – globally.

• From January 2011 to September 2012, the United States exported over 8.6 million tons of petcoke to China, most of which was likely burnt in coal-fired power plants.

Source: Petroleum Coke: The Coal Hiding In The Tar Sands

The largest global trader of petcoke in the world is the Florida-based Oxbow Corporation, which is owned by William Koch – the brother of Charles and David, Oil Change International reports.

In April, the United States exported the second highest-ever petcoke volume, according to the Energy Information Agency (EIA). The high levels were spurred by Asian demand, an EIA report states. In Asia, the oil refining byproduct is used for “generating electricity, making steel, and manufacturing cement.”

The US provides over one-half of the world’s petcoke. China buys more US petcoke than any other country, followed by Japan, Brazil, Turkey, and Mexico.

While the world is already struggling to curb carbon emissions, petcoke represents just one more reason to consider the impacts of exploiting tar sands bitumen. According to Oil Change International, “The proliferation of tar sands bitumen and heavy oil processing in the United States is turning American refineries into coal factories.”

As of last year, 134 operating US refineries were equipped to produce petcoke. Those refineries produced over 61.5 million tons of petcoke in 2011, over 60 percent of which was exported. About 75 percent of petcoke produced is used as a fuel.

Alisha is a writer and researcher with Ring of Fire. Follow her on Twitter @childoftheearth.