Gov. Kim Reynolds and Sen. Joni Ernst are expressing concerns about advanced biofuels. The Iowa lawmakers spoke before an EPA hearing on the renewable fuel standard Tuesday as the agency considers the biodiesel level for 2019. Ernst said the number of advanced biofuels should be higher because a lower number "would create uncertainty and slow investment in advanced biofuels." Reynolds said the proposed number of slightly more than 4.2 billion gallons should be higher because the demand is there.