Agree and disagree. While you're right that there are several other sources like Shale gas and to be honest I don't have estimates of their total potential. However, you can be almost certain that NO other conventional source - with possible exception of north pole oil - can meet our increasing energy needs.

This results in simple demand supply dynamics which would enable alternative sources that are currently too costly to compete with oil to be cost competitive. e.g. wind energy is around 11 - 12 Rs /unit and Solar comes to at least 18 - 20 Rs / unit. With increased economies of scale, innovation etc. these modes can become mainstream. For example, China has a stated policy (ref: copenhegan summit) to reduce their coal based energy production by as much as 40% in next 20 years. China is building wind farms like there's no tomorrow and players like Suzlon are well positioned to tap this market.

And pray how that decrease in consumption be achieved while the erstwhile third world is buying cars like there's no tomorrow and per capita energy consumption in countries like India are growing at 10-15%?

Just a little piece of trivia for you - Delhi needed around 60 MW of electricity in 1950s that increased to around 200 MW by 1965 ... Last week's Delhi's peak requirement was 4700 MW.

       In the Light of anti-nuclear opinion,huge National solar mission project we must rejuvenate this topic.
       India is a huge energy deficit country.Thermal power is contributing some 75 per of power.Now a days there is lot of uncertainty in the form of coal availability and linkages,land acquisition problems,people agitationshttp://www.thehindu.com/news/states/tamil-nadu/article435466.ece?service=mobile
          http://www.outlookindia.com/article.aspx?266538
                  Hydro power projects are also facing similar problems.In the scenario of Japan nuclear crisis Nuclear energy projects may be shelved.If govt go ahead firmly Local peoples may agitate heavily.
                   Eventually this will mean a bonanza for Alternate energy.So from five year perspective it make sense for us to invest in companies        

A.Alternative energy producers(Huge capital+Low ROE+high depr benefits)
b.Technology providers
C.Turn key service providers.
                    In the Scenario of huge opportunity in the form of National solar mission i am requesting all the members to put your valuable inputs.

                       Great news for Indian pv manufacturers
             Govt recently banned the import of equipment for projects under the National Solar Mission.The regulation mandates that the modules for a solar power plant should be manufactured in India.The Indian solar energy market, at 500 MW, is expected to reach 800 MW by 2011.The government plans to have an installed capacity of 1 GW by 2011 and 20 GW by 2020. Secondly, there will be rethinking all over the world after the Japan crisis. Many countries plan to have a 20-25% of their capacity from renewable energy.
              So,there is huge opportunity for photo voltaic manufacturers and other equipment manufacturers (also for us as investors).I think Moserbaer is the largest in India.Other companies are BHEL,TATABpSOLAR,XL telecom, PAEL, WEB SOL ENERGY etc.
              Key is to find a company having technology and good balance sheet.I am inviting your valuable feedback.