"Cleantech" being a catch-all term that covers a wide range of mostly disconnected industries and markets and technologies, it's always interesting to note commonalities across subsectors where you can find them.
One such macrotrend which I believe will end up driving a lot of cleantech innovation is the emergence of distributed alternatives to previously centralized processes.
There are two factors underlying this trend.
First of all, long-range transportation costs appear likely to be higher going forward, simply because they are so dependent upon oil prices. This is not a given. But there are reasons to believe oil prices are likely to rise over the medium to long run, including supply-demand dynamics ("peak oil" and all that), the possibility of climate-related externalities being priced in, or further geopolitical conflicts leading to greater volatility if not outright price increases. There are other reasons to believe oil prices might not rise or may even fall, such as new extraction techniques (fracking, EOR, more efficient tar sands production, etc), or even the emergence of alternative fuels and drivetrains (although this appears more likely to make an impact on short-haul routes in any near-term). But the current outlook appears to signal more risk of price increases than price decreases going forward.
Oil prices appear to be headed upward, and they will likely dictate long-range transportation costs for the foreseeable future. Some industries such as chemicals already see regionalized production trending upward because of transportation costs, for example.
Secondly, we're getting better at making, distributing and controlling things cheaply in smaller batches.
Economies of scale have traditionally dominated many industries such as manufacturing, chemicals, energy production and distribution. But advanced technologies are disrupting this dynamic. IT innovations make it easier to track small batches of inventory, identify and sell to buyers with smaller appetites, and to better remotely automate and monitor processes. Innovations in flexible robotics and manufacturing (3D printing, etc) make it less costly to make things in small batches. And modularization trends across industries as diverse as power generation, biofuels manufacturing, and housing construction mean that "building blocks" are more readily available to be built into whatever size production facility or end product is desired for any particular circumstance.
What these two trends mean in combination is that we're seeing a shift toward more localized production and distribution of physical products, much of which is directly related to cleantech.
This is, of course, most discussed and visible in electricity. Distributed generation, storage and customer-side load control are challenging the traditional utility model with its natural monopoly based upon the distribution and management of centralized power production, as many have noted.
But we're seeing very similar, albeit perhaps more early-stage, trends toward localized production in biofuels, in food, in wastewater treatment, and even in hardware manufacturing and metals production (via e-waste recycling). For higher-end products, not only transportation cost in dollars but also the time delays are often driving a desire for more localized production -- tomorrow's cleantech hardware may more often be assembled in the U.S. than in southeastern China, for example.
This macrotrend toward smaller-scale, localized production might appear to fly in the face of much of what we've called "cleantech" over the past decade, such as the quest for ever larger "commercial-scale" production of biofuels, of solar panel manufacturing plants, of desalination plants. But even in these areas, modularization techniques are more common now than they used to be. In large part this has been driven out of necessity -- less-available capital for large amounts of steel in the ground leads entrepreneurs and their backers to seek approaches that require less money spent to get to "Dollar One" of revenue. But it's also been driven by new capabilities. And thus not only startups are getting into the trend; I think we'll see more big companies start to embrace the localization vision as well.
But when they do, it may require them to buy the technologies necessary for them to shift in this direction, rather than be able to build them from scratch internally. And because of this, and the deeply entrenched centralized production/distribution networks many are dependent upon, this localization trend remains a highly entrepreneurial one. And that makes it pretty interesting for investors like me.