Environmental costs are part of the economy. The cost of solar includes paying highly-skilled workers to build the panels. The cost of coal includes paying doctors to treat the resulting increase in lung disease, etc.
The problem is that we don't measure economic activity accurately, because we ignore draw-down of capital (human, natural, or otherwise). Fukushima actually increased Japan's GDP for a quarter, because the damage-response activity gets counted in GDP while the loss of physical capital does not. Fossil fuel use suffers from this problem in two ways: 1) the value of the capital removed from the ground isn't counted (i.e. nobody counts selling off their family furniture as net positive income, but resource-rich countries count selling off oil or minerals as such); 2) the loss of human and environmental capital is ignored (strip mining mountains causes rain to wash away river banks, and that's money directly out of someone's pocket).
The problem is that we don't measure economic activity accurately, because we ignore draw-down of capital (human, natural, or otherwise). Fukushima actually increased Japan's GDP for a quarter, because the damage-response activity gets counted in GDP while the loss of physical capital does not. Fossil fuel use suffers from this problem in two ways: 1) the value of the capital removed from the ground isn't counted (i.e. nobody counts selling off their family furniture as net positive income, but resource-rich countries count selling off oil or minerals as such); 2) the loss of human and environmental capital is ignored (strip mining mountains causes rain to wash away river banks, and that's money directly out of someone's pocket).