At first glance, the pathway from toilet to tanker might seem implausible. But the chemistry is straightforward. Wastewater plants produce sludge \u2014 the thickened residue left after sewage is treated and cleaned. Mannheim\u2019s plant ferments this sludge in oxygen-free tanks, yielding biogas rich in methane and carbon dioxide, which is usually burned for heat or flared off.<\/p>\n
Icodos\u2019 innovation is to clean and upgrade that gas. \u201cThe sewage gas is dried, desulfurized, and then the carbon dioxide is separated from the rest,\u201d Strittmatter explains. Using renewable electricity, the captured carbon dioxide is then combined with hydrogen through a catalytic process to form methanol \u2014 a liquid fuel that can run ship engines with only minor modifications.<\/p>\n
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The Mannheim 001 process. As a nearly-climate-neutral alternative to heavy fuel oil, e-Methanol is being hailed as central to the sustainable transformation of the shipping industry. Image courtesy of Icodos.<\/p>\n
\u201cWastewater exists everywhere,\u201d says Strittmatter, gesturing to a model plant pinned on his office wall. \u201cThe sludge contains up to three times more energy than the treatment process needs. We just usually waste it. Why not use it as fuel?\u201d<\/p>\n
International shipping, which carries about 90 percent of world trade, is responsible for approximately three percent<\/a> of global greenhouse gas emissions \u2014 more than the entire country of Germany. Cargo ships also spew sulfur oxides and particulates, contributing to air pollution along coastlines and in port cities.<\/p>\n For decades, the sector has resisted cleaner alternatives, arguing that no scalable, affordable fuels existed. But that defense is crumbling. Regulators, customers and climate urgency are pushing the industry to look for replacements. Methanol is emerging as one of the most promising.<\/p>\n \t\t\t\tWeighed down by negative news? It is energy-dense, can be stored and transported in liquid form, and \u2014 crucially \u2014 many ship engines can be converted to run on it. Global giants like Maersk and CMA CGM<\/a> are already operating methanol-powered container vessels. The International Maritime Organization<\/a> has set a target to reach net-zero greenhouse gas emissions from global shipping by 2050, making green fuels essential.<\/p>\n \u201cShipping companies have very strong ambitions to reduce their footprint,\u201d says Strittmatter. \u201cIKEA, Amazon and other big retailers increasingly want green supply chains. If the transport is dirty, the whole brand suffers.\u201d<\/p>\n Built at a cost of nearly \u20ac4 million ($4.6 million), with funding from the Karlsruhe Institute of Technology, the European Commission and Mannheim\u2019s own Climate Fund, Mannheim 001 currently produces about 15,000 liters of methanol per year \u2014 enough to fuel smaller workboats or local needs, but nowhere near enough for a large container ship, which consumes tens of millions of liters annually. \u201cA ship needs about as much fuel as 100,000 cars,\u201d says Strittmatter, who has already secured an industrial area near Paris in France for the next upscaled plant, partly funded with a grant from the European Union.<\/p>\n The vision extends beyond shipping. Methanol is also a feedstock for plastics, solvents and other chemicals. A wastewater-to-methanol system could, in theory, help decarbonize multiple industries. But shipping is the most urgent target. \u201cIt\u2019s literally waste that\u2019s flushed away every day,\u201d says Strittmatter. \u201cWe\u2019re turning a liability into a resource.\u201d<\/p>\n Wastewater is a massive, underused resource. Each day, humanity produces about 900 million kilograms of feces<\/a> and nearly 10 billion liters of urine. Harnessing even a fraction could help decarbonize industries, fertilize fields and power communities. Globally, less than 20 percent<\/a> of sewage is treated before release, according to the UN. Even in highly regulated countries like Germany, where treatment rates exceed 96 percent<\/a>, sewage plants consume enormous amounts of energy. Some municipalities spend up to 60 percent of their annual budgets running them, according to the German magazine brand eins<\/a>.<\/p>\n What if instead of burning energy to destroy sludge, we flipped the equation and mined its hidden power? Sewage is rich in carbon, nitrogen and phosphorus \u2014 the building blocks of fuel, fertilizer and food. A new wave of innovators is showing how to turn waste into wealth.<\/p>\n One of the most striking efforts comes from another German startup: Shit2Power<\/a>. The company has designed modular, shipping-container-sized units that sit directly beside wastewater plants. Inside, a thermochemical gasification process transforms sewage sludge into green hydrogen.<\/p>\n Shit2Power works locally and is particularly useful for small municipalities. A small town of 30,000 residents could cover up to a third of its own electricity needs, explains co-founder and CEO Nina Heine. For many municipalities, that would amount to a small-scale energy transition right on their doorstep \u2014 and a relief for their waste balance sheets. This year, the Berlin startup plans to build its first facility; so far, the technology has only been tested in the lab.<\/p>\n \n\t\t\t \t\t\t\t\t\tWait, you’re not a member yet?<\/p>\n \n\t\t\t\t\t\tJoin the Reasons to be Cheerful community by supporting our nonprofit publication and giving what you can.\n\t\t\t\t\t<\/p>\n
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Mannheim 001\u2019s anaerobic digester. At the wastewater treatment plant, biogas is converted into methanol using electricity and hydrogen. Photo courtesy of Icodos.<\/p>\n![](\"https:\/\/www.newsbeep.com\/ie\/wp-content\/uploads\/2025\/11\/memb-banner-mob.jpg\"\/)
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According to Icodos, scaling sewage-to-methanol worldwide could cover the entire fuel demand of the global shipping sector. Credit: MartinLueke\/Shutterstock.<\/p>\n