Locational marginal pricing (LMP) promised to improve the efficiency of the wholesale power market by ensuring that electricity prices reflect the cost of transmission congestion and that the lowest-cost supply is delivered when the grid is constrained. The concept makes sense in theory-but not in practice, if you are an LMP "node." Review of the first 10 months of data from ISO New England shows that LMP has significantly eroded the market value of existing generating assets and effectively closed the door on new plants.