Illinois made big strides to reduce energy use last year while its neighbor on the other side of the Mississippi River still lags much of the rest of the country, according to a study by the American Council for an Energy-Efficient Economy.

The nonprofit advocacy group's fifth-annual energy efficiency scorecard ranks Illinois 17th in the nation for its energy efficiency efforts, up from 25th last year. Missouri is tied with West Virginia for 44th, falling a spot from 2010.

The study evaluates states' policies and programs aimed at reducing energy use in homes, businesses and the transportation sector. Massachusetts overtook California for the top spot in the study. North Dakota was last.

Among some of the differences between Missouri and Illinois:

• Missouri's budget for electricity efficiency programs totaled $40.5 million in 2010, or 0.6 percent of revenue. Illinois' budget was $165.5 million, or 1.2 percent of the state's total revenue.

• Missouri lacks policies to encourage efficiency in the transportation sector. Illinois allows a rebate of up to $4,000 on the extra cost of an electric vehicle versus a comparable gas model.

• Missouri has no statewide energy efficiency building code and lacks data on municipalities' efficiency code compliance rates. Illinois, which does have a statewide code, got a federal grant to study compliance rates.

• Perhaps the biggest policy difference between the states: Illinois has an energy efficiency standard that requires investor-owned utilities to cut energy use by 25 percent from 2007 to 2025. There is no such requirement in Missouri.

ACEEE is the same group that this summer published a study suggesting Missourians could save $6.1 billion on energy expenditures by 2025 through new or expanded efficiency policies and programs.

The programs outlined could reduce Missouri's electricity use by 17 percent and shrink natural gas consumption by 10 percent, the group said.