These 7 US cities are the powerhouses of clean tech

The Trump administration's 2018 budget proposal would impose a nearly 20% cut on the Office of Science within the Department of Energy — a total of $900 million. It would also eliminate the Advanced Research Projects Agency-Energy, which supports moon-shot energy projects too risky for private investment, as well as loan programs like the Advanced Technology Vehicle Manufacturing Program, which provided early support to Tesla.

As researchers Devashree Saha and Mark Muro at the Brookings Institution note in a new report, those changes could stunt the development of viable clean energy sources. The report analyzes data on clean-tech patents from 2011 to 2016, and ranks cities based on which ones boast the highest number of patents filed.

In determining the list, the researchers took a variety of sectors into account, including bioenergy, hydropower, solar power, and energy storage.

In Brookings' study of 381 cities, Ann Arbor had the most patents for clean technologies relative to the city's size, especially in the categories of transportation and energy storage. This may be because Ann Arbor is home to the University of Michigan, which has an institute devoted to alternative energy research.

According to the report, 186,500 patents have been granted in the US since 2011 across 14 clean-tech categories. (It's important to remember, however, that researchers can patent inventions regardless of whether the concepts have been shown to work).

The report also highlights the extent to which clean-tech patenting is concentrated in few categories. Advanced green materials (e.g. alternatives to plastic), energy efficiency, and transportation (e.g. hydrogen fuel cells for planes) each accounted for 18% of the total patenting during the time period analyzed. Categories like geothermal energy and hydropower, on the other hand, each made up for less than 1% of patents since 2011.

The number of clean-tech patents granted has actually declined in recent years. Between 2014 and 2016, it decreased by 9 percent, according to the report. f the Trump administration's proposed budget moves forward, the number of clean-tech patents would plummet even more.

Check out the full interactive map of patent distribution on Brookings' site.