Deep-negative ethanol gains no extra 45Z value, hinges on California LCFS

Treasury and IRS on February 3 proposed 45Z rules that floor crop-based feedstocks at zero CI, even when ethanol can model at -20 to -50. Published in the Federal Register on February 4, the proposal sets the credit window for fuels produced after December 31, 2024 and sold before January 1, 2030. That leaves deep-negative ethanol priced by state LCFS markets, not by any extra federal premium.

Federal rules stop the upside at zero

Section 45Z, created by Congress in the Inflation Reduction Act of 2022 as a clean fuel production credit, leaves a hard boundary for crop-based ethanol in its proposed implementation. IRS Notice 2024-49 had already required a signed IRS registration letter dated on or before January 1, 2025 for taxpayers seeking to claim the credit on production starting January 1, 2025.

Both the American Coalition for Ethanol and the Renewable Fuels Association filed formal comments in April 2026. The crop-based feedstock floor in 45Z means a plant that reaches a negative carbon intensity still does not earn a larger federal credit than one that simply hits zero.

California remains the price setter

California is where that lost value shows up first. The California Air Resources Board’s Low Carbon Fuel Standard has been a cornerstone of the state’s climate strategy since 2011 and has driven innovation in low-carbon fuels. In a University of Pennsylvania Kleinman Center report dated October 7, 2024, Danny Cullenward wrote that the program has become increasingly controversial because of its reliance on market mechanisms.

For ethanol, the market signal has been strong enough to keep rewarding incremental CI cuts. USDA materials say the average carbon intensity of ethanol fuel has fallen by about 25 percent since the LCFS began in 2011, reflecting changes in how ethanol plants operate. The Renewable Fuels Association says ethanol’s CI is falling faster than any other low-carbon fuel supplied to California, which makes the LCFS the main monetization channel for very low-CI gallons.

What gets a plant into deep-negative territory

Deep-negative scores are technically achievable when producers stack three levers: on-site carbon capture and storage, renewable electricity, and lower farm emissions. Under that model, ethanol producers can engineer CI scores in the minus-20 to minus-50 range, depending on the plant, the power mix, the feedstock and the storage pathway.

At the farm level, no-till or low-till farming, cover crops and precision fertilizer use can reduce emissions tied to corn production. Those practices matter because the feedstock piece of the lifecycle can be pushed down before the gallon ever reaches the plant gate. Add CCS at the ethanol plant and renewable power on site, and the lifecycle math can move from low-carbon to carbon-negative.

The remaining constraint is policy design. Under current 45Z guidance, crop-based feedstocks are floored at zero CI, so a modeled score below zero does not create extra federal value. That leaves the project economics to be completed elsewhere, most often in California’s LCFS, where lower CI still translates into tradable value.

USDA’s feedstock framework adds another layer

USDA’s Technical Guidelines for the Production of Regenerative Agricultural Biofuel Feedstocks, issued on June 25, 2026, added a federal framework for measuring regenerative practices. The guidance gives feedstock measurement a more formal federal structure for producers trying to document lower farm emissions inside a lifecycle model.

That measurement step does not solve the monetization gap by itself. It improves the case that a corn supply chain can substantiate lower emissions, but the federal 45Z floor still stops crop-based feedstocks at zero.

Why the LCFS still carries the business case

California’s LCFS is now the most important credit stack for deep-negative ethanol because it is the only large market in this framework that still pays for going below zero. CARB’s program has been in place since 2011, and its market structure creates a direct value path for lower lifecycle emissions.