This paper describes two variant of the Indian MARKAL model, a long-term technology oriented optimization model for energy-environment planning for India. The first variant uses stochastic programming to include future uncertainties in the analysis. Details of model formulation, results and sensitivity analysis are described here. The second variant uses an innovative approach to simulate price sensitive demands within a linear formulation. The analysis incorporating future uncertainties suggests that it is prudent to reduce carbon emission in anticipation of a global regime in the future. Modeling with price elastic demands estimates up to ten percent reduction in carbon emission due to reduced demands, under a severe carbon tax.