What if repealing one regulation could help the environment, reduce food prices for consumers and improve the lot of the world's poor?

Ethanol mandate

https://www.forbes.com/sites/jamesconca/2014/04/20/its-final-corn-ethanol-is-of-no-use/

In 2000, over 90% of the U.S. corn crop went to feed people and livestock, many in undeveloped countries, with less than 5% used to produce ethanol. In 2013, however, 40% went to produce ethanol, 45% was used to feed livestock, and only 15% was used for food and beverage (AgMRC).

On average, one bushel of corn can be used to produce just under three gallons of ethanol. If all of the present production of corn in the U.S. were converted into ethanol, it would only displace 25% of that 130 billion.

But it would completely disrupt food supplies, livestock feed, and many poor economies in the Western Hemisphere because the U.S. produces 40% of the world’s corn.

In 2014, the U.S. used almost 5 billion bushels of corn to produce over 13 billion gallons of ethanol fuel. The grain required to fill a 25-gallon gas tank with ethanol can feed one person for a year, so the amount of corn used to make that 13 billion gallons of ethanol will not feed the almost 500 million people it was feeding in 2000. This is the entire population of the Western Hemisphere outside of the United States.

In 2007, the global price of corn doubled as a result of an explosion in ethanol production in the U.S.

Groups like Oxfam and the Environmental Working Group oppose biofuels because they push up food prices and disproportionately affect the poor.

https://www.forbes.com/sites/susandudley/2017/10/27/drain-the-swamp-trump-opts-for-politics-as-usual-when-it-comes-to-ethanol/#fa109ba6064c

An article in the journal Energy finds that the RFS “unambiguously” increases emissions of CO2—a greenhouse gas. These findings corroborate an earlier article in the journal Science, which found that biofuels increase carbon emissions by 93% compared to gasoline when the effects of land use change are considered. Other studies have also shown that increases in corn-based ethanol production damage ecosystems, wildlife habitat, and fisheries.

Unfortunately, Brazil is clear-cutting almost a million acres of tropical forest per year to produce biofuel from these crops, and shipping much of the fuel all the way to Europe. The net effect is about 50% more carbon emitted by using these biofuels than using petroleum fuels (Eric Holt-Giménez, The Politics of Food).