World-First Engine Test: Turning Sugarcane into Clean Power

In a pioneering leap toward sustainable energy, Wärtsilä, a Finnish technology leader, has partnered with Brazil’s Energetica Suape II S.A., majority-owned by Grupo Econômico 4M, to launch the world’s first engine test converting sugarcane-derived ethanol into clean electricity. Announced on March 25, 2025, this trial at the Suape II power station in Recife, Brazil, aims to harness ethanol’s potential for large-scale power generation, leveraging Brazil’s sugarcane bounty. With testing slated for April 2026, this initiative blends cutting-edge engineering with environmental goals, offering a detailed blueprint for a cleaner energy future.

The Technical Backbone: Wärtsilä 32M Engine
At the core of this trial is the Wärtsilä 32M, a medium-speed, multi-fuel engine designed for flexibility. Typically used in power plants and marine applications, it delivers 500–580 kW per cylinder (up to 11.6 MW total for a 20-cylinder configuration) at 720–750 RPM. For this test, Wärtsilä will adapt the engine to run on anhydrous sugarcane ethanol (99.5% purity), which has a lower heating value (LHV) of ~26.8 MJ/kg compared to diesel’s ~42.7 MJ/kg. This requires:

• Fuel Injection Tuning: Adjusted injection timing and pressure to handle ethanol’s higher octane (108 RON) and lower energy density.
• Combustion Optimization: Modified air-fuel ratios (ethanol requires ~9:1 vs. diesel’s 14.5:1) to ensure complete combustion and minimize unburnt hydrocarbons.
• Corrosion Resistance: Upgraded materials (e.g., stainless steel components) to withstand ethanol’s solvent properties.

Testing begins in April 2026, spanning up to 4,000 hours over two years—equivalent to 167 days of continuous operation—to validate reliability, efficiency, and emissions under grid-scale loads (likely 5–10 MW output).

Why Sugarcane Ethanol? The Technical Case
Brazil produces over 25% of global ethanol (~35 billion liters in 2023), with sugarcane yielding 6,000–7,000 L/ha—far more efficient than corn (400 L/ha). Ethanol’s energy content comes from fermentation of sugarcane juice or molasses, yielding:

• Energy Yield: ~80 GJ/ha, with 70% of biomass energy converted to liquid fuel.
• Carbon Cycle: Lifecycle CO₂ emissions are ~0.5 kg/L (vs. 2.8 kg/L for gasoline), offset by sugarcane’s uptake of 15–20 tons CO₂/ha during growth.

The International Energy Agency’s Net Zero by 2050 scenario projects biofuels must boost electricity generation from 700 TWh (2023) to 1,250 TWh by 2030. Ethanol’s high availability and transportability (via pipelines or tankers) make it ideal for dispatchable power, filling gaps left by variable renewables. In Brazil, ethanol replaced 44% of fossil fuel use in transport by 2023, avoiding 660 million tons of CO₂—proof of its scalability.

The Setup: Suape II Power Station
Located in Recife, the Suape II plant currently operates Wärtsilä engines on natural gas or diesel under a power purchase agreement expiring in 2026. The trial integrates:

• Fuel Supply: Ethanol sourced from local mills (e.g., Pernambuco’s sugarcane belt), piped or trucked in.
• Engine Retrofit: One 32M unit converted, with others as backup or control.
• O&M Agreement: Wärtsilä oversees operations (booked Q4 2024), monitoring NOx, CO, and particulate emissions, expected to drop 50–80% vs. diesel (ethanol burns cleaner due to oxygen content).

The initiative stems from Carlos Alberto Mansur Filho of Grupo Econômico 4M, building on a decade-long Wärtsilä partnership. It’s part of the WISE (Wide and Intelligent Sustainable Energy) program, co-funded by Business Finland, targeting a suite of sustainable fuels.

Technical Challenges and Solutions

1. Lower Energy Density:

• Ethanol’s LHV means ~60% more volume (1.6 L ethanol = 1 L diesel energy). The plant may need larger fuel storage (~50–100 m³/day for 10 MW) and higher injection rates.
• Solution: Dual-fuel capability retains diesel as a fallback, easing transition.

1. Engine Efficiency:

• Thermal efficiency may dip from ~45% (diesel) to 40–42% due to ethanol’s properties. Wärtsilä’s testing will optimize compression ratios (likely 11:1–12:1 vs. diesel’s 14:1).
• Solution: Advanced control systems adjust spark timing (if spark-ignited) or injection (if compression-ignited).

1. Infrastructure:

• Ethanol requires dedicated tanks and seals (e.g., Viton gaskets) to prevent leakage or degradation.
• Solution: Retrofit costs are offset by ethanol’s lower price (~$0.50/L vs. $0.80/L diesel in Brazil, 2025 estimates).

Potential Impact: Numbers and Scale

• Power Output: A single 32M engine at 10 MW running 24/7 could generate ~87,600 MWh annually on ethanol, powering ~20,000 Brazilian households.
• Emissions Savings: At 0.5 kg CO₂/kWh (vs. 0.8 kg/kWh for diesel), it could cut ~26,000 tons CO₂/year per engine.
• Scalability: Success could convert Brazil’s 1,000+ MW of flexible thermal plants, leveraging 400+ sugarcane mills. Globally, sugarcane nations like India (5 billion L ethanol/year) could follow.

Brazil’s June 2025 capacity auction now lists ethanol as a fuel option, hinting at policy backing. Anders Lindberg, President of Wärtsilä Energy, calls it a “game-changer,” envisioning ethanol as a bridge to net zero.

Broader Implications: This isn’t just about Brazil. Aviation and shipping, seeking biofuels to cut 15–20% of global emissions, could adapt ethanol blends. Challenges remain—land-use debates (though sugarcane’s yield mitigates this), upfront costs (~$5–10 million for retrofits), and competition with transport fuel demand. Yet, with ethanol’s closed carbon cycle and Brazil’s infrastructure, the trial could spark a bioenergy revolution.

Looking Ahead
Starting April 2026, the Wärtsilä 32M will hum with sugarcane ethanol, its pistons proving a sweet hypothesis: renewable fuels can power our grids cleanly and reliably. If successful, this world-first test could redefine energy systems, one cane stalk at a time. Watch this space—technical data from 4,000 hours of runtime will tell the tale.