Google is pulling the plug on another half-dozen research projects, including an attempt to improve the efficiency of solar power, in the third round of cost cuts since founder Larry Page became chief executive earlier this year.
The RE<C project, Renewable Energy Cheaper Than Coal, will be axed along with Google Wave, a once-promising instant messaging service, Knol, Google's answer to Wikipedia, and a string of other programmes. The company called the closures "spring cleaning, out of season".
Perturbed by rising costs, Wall Street investors have been calling on Google to rationalise its sprawling portfolio of research projects, which range from funding for green energy and space travel to in-house development of robots and self-driving cars.
The company has long allowed its engineers to work part of their time on long-term and potentially world-changing ideas. Some of these projects may turn into lucrative businesses in the future, managers hope, and in the meanwhile they make Google a magnet for some of the top talent in Silicon Valley.
However, Mr Page said at the time of his elevation to the chief executive job in April that he would prune projects that had the least chance of success.
Announcing the latest cuts on the company's blog, Google's senior vice-president of operations, Urs Hölzle, said: "We're in the process of shutting a number of products which haven't had the impact we'd hoped for, integrating others as features into our broader product efforts, and ending several which have shown us a different path forward."
Several of the projects in the latest cull had already been deprioritised by Google, including Wave and Google Gears, which had allowed app developers to create smartphone software based on Google products.
In 2009, the company's so-called green energy tsar, Bill Weihl, told Reuters that he expected to demonstrate working technology that could produce renewable energy at a cheaper price than coal, and said it was "even odds" that the technology would be ready in three years. Mr Weihl left Google earlier this month.