There has been a huge environmental, social and political push to increase renewable penetration.  However, with lack of a better word, the increase in renewable penetration has been rather ‘slow’.  What are the barriers to renewable integration?

 There are four main barriers/challenges to increasing the amount of renewables on the grid:

 (1) Limited dispatchable renewable resources
Integrating economical dispatchable  renewables makes the most sense.  We have been using hydro electricity before we started relying on fossil fuels.  The problem is that dispatchable renewable resources such as hydro are limited.  For example, we have used up all easily accessible hydro resources for about 100 years now.  Geothermal is also dispatchable and in the last 20 to 30 years are coming close to using all easily accessible geothermal resources. 

 (2) Environmental pressure on renewable resources
This is the one that gets me.  Environmental pressure is slowing down the rate at which we are integrating renewables substantially.  For this I would like to introduce my favorite law, the law of no free lunch.  Yes, hydro plants will affect fish, wind generators birds, and solar plants desert tortoise.  However, if renewable plants do not get built, coal and natural gas plants will.  The electricity we consume has to get generated, and the generation will have some impacts.  That is why CONSERVATION is the most effective environmental measure we can all take. 

 Now, I’m not saying we should not keep a check on renewable developers, but we should always weigh in trade-offs.  I also do not think we should stop renewable development, but rather find ways to make renewables have less of an impact on the environment.  I am not an expert in this field, but this means giving fish paths around dams, having bird deterring signals on wind turbines, and developing solar power plants with minimal impact on tortoises.  

 (3) Transmission lines
Renewable generation is generally resource dependent.  What I mean is that wind generators make the most economic sense in geographic areas where wind are high, solar generation makes most sense in the desert where solar irradiance is high and large real estates are available.  These resources are generally some distance away from cities and electric demand.  Transmission lines take years to plan and build.  For example in California transmission is the single most barrier for the state to meet its goal of 20% renewable penetration by 2010.  The transmission lines take years on the order of 5 to 10 years to build.  Transmission is a major barrier to renewable penetration.

 (4) Intermittency and grid balancing
Many of you may be surprised cost is not one of my main points, but it is not because many renewables including wind, hydro, geothermal and solar thermal power plants are starting to be cost competitive with coal and natural gas.  With natural gas prices risks and vulnerability and coal environmental pressures renewables are just as economical feasible as any energy choice.  One of the main challenges is that renewables are dependent on meteorological conditions.  Particularly wind and solar generation output are dependent on the wind and the sun.  This fact makes integrating significant amount of intermittent renewable resources difficult in terms of balancing the grid. 

 In our current electric system we must generate electricity in direct proportion to the electricity we consume.  With increasing amount of renewable penetration this gets increasing more difficult.  It is easy to incorporate 10 to 20% intermittent renewables.  However, with increased amount we must be very careful to maintain grid reliability.  More on this in the weeks to come, but this is why dispatchable renewable resources as so critical because they can be used directly to balance the grid, while the dispatch of wind resources is ultimately dependent on wind speeds.