The UK is lagging behind most of its major competitors in alternative energy research, according to a new ranking.
The league table, devised by journal publisher Elsevier, assesses the work of 3,000 research institutions and universities around the world.
Imperial College London is the only UK university to appear in the top 25, placing it 14th behind eight US, two German, one Japanese and two Chinese institutions.
The study, released this week and provided exclusively to Times Higher Education, uses a new method of determining performance.
Institutions are ranked according to the number of research papers they had published between 2003 and 2007 within their "distinctive competencies" (areas they are good at) in alternative energy research.
This methodology, Elsevier says, is a more accurate way of determining leadership in a given area.
"Output in distinctive competencies reveals the degree to which institutions have constructed multi-disciplinary networks within their organisation focused on achieving specific breakthroughs," it says.
The study also looks at countries' performance across three main topics of alternative energy, revealing what it describes as a "surprising ... somewhat weak performance" from the UK.
The country ranked sixth in the publication of solar/photovoltaic research papers, of which around half were in its distinctive competencies.
It was ranked seventh in the production of fuel cell research papers, with about a quarter published in distinctive competencies, and came 12th in the environmentally related energy papers category, with the proportion in distinctive competencies undetermined.
Although the US produced the most papers across all areas, it was Germany that published the highest number of papers within its distinctive competencies.
Dick Klavans, a senior development adviser for the project, said: "The UK definitely lags behind in alternative energy research."
Elsevier is due to launch a new product to assess institutions based on distinctive competencies later this month.