On Tuesday, I learned from a reader that a CO2 emissions trading platform for California, called the California Climate Exchange, had just been launched. The new California carbon bourse will look to service organizations with emission reduction obligations under the state’s AB 32. Who’s behind this? None other than Climate Exchange plc (CXCHF.PK), a company we’ve discussed on several occasions in the past. On Wednesday, Mark Gongloff at the WSJ’s Energy Roundup informed us that HSBC was going green. This is the latest in a series of similar commitments by global financial institutions. Good business sense or a waste if shareholders’ money? The future will tell. On Wednesday, Dana Childs at Inside Greentech told us that Chinese solar companies had gotten spanked after Solarfun missed its quarter. Alt energy, despite impressive revenue growth, remains a very risky asset class marred in volatility. This fact should always remain at the back of an investor’s mind. On Wednesday, Rob Day at Cleantech Investing examined, for us, the issue of whether or not there is a biofuel bubble currently underway. The article looks at this debate from a venture capital angle, but some of the key points, such as the future of cellulosic ethanol, bear relevance for public market investors. On Thursday, Environmental Finance informed us that, last week, European carbon prices had spiked to a 13-month high. It may be too early to tell, but my sense is that the second phase of the European Emissions Trading Scheme, which will coincide with the initiation of regulation-driven carbon trading in the US, will be far more successful than was phase one. On Friday, Biopact gave us the heads up on a recent academic journal article that found that emissions trading in the EU was one of “the most significant accomplishments in climate policy to date”. Moreover, contrary to what has been claimed in the popular press, the article found that emissions trading in Europe was indeed working well. The Week in Cleantech is a weekly roundup of our favorite cleantech and alt energy blog posts and stories from across the web. If you know of a good piece that you think should be included here, don’t hesitate to let us know!