Though renewable energy has wide potential as the new energy resource, there are still concerns as to whether or not such ways are really environmentally friendly. Some experts say that even though the sources of renewable energy are mostly "natural," the methods of extracting such energy is still questionable and in the end still produces doubts as to whether or not this process is beneficial to the environment. There is also the question of consistence and longevity as most of the sources or renewable energy are based on very unpredictable forces of nature. The "unpredictable factor" is what makes other people doubt if the renewable energy sources could sustain a very wide demand of energy and if it could really fulfill the research results for the future of alternative energy.
There are certain disadvantages of using renewable energy sources as well. The current capital cost for equipment to convert renewable energy such as solar, wind, and tide is very high, but in the long run, as Al Gore puts it, production costs would become negligible in the future, as compared to conventional sources of energy. Another major disadvantage is that it is difficult to generate the quantities of electricity that are as large as those produced by traditional fossil fuel generators. However, if renewable energy is produced uniformly, then collective production would become much more than traditional production. Few experts believe that installing wind and hydropower plants will disturb the natural flow of winds and rivers in the respective region.
As you can see, renewable energy is a very interesting topic as there are still many discoveries still waiting to be unveiled and also some possible limitations that could hinder this fast-growing trend. If used properly and efficiently, renewable energy sources can solve the energy crisis, which is looming in front of the world.