Energy generation, possibly energy storage. Nearly all of our modern production, processing, and logistics to move it is constrained by the cost of energy. Any

Energy generation, possibly energy storage. Nearly all of our modern production, processing, and logistics to move it is constrained by the cost of energy. Any sort of atmospheric scrubbing is also energy restrained, our food production is energy restrained as fertilizer is still produce from fossil fuels. Refined material costs are largely dependent on the fuel costs of extracting and processing raw ore. The only problem with investing in energy production is it being a slow grind, you won't likely see any large gains, but it is a secure bet so long as civilization exists.