As many know already, and has been shared here periodically, the energy available from any current alternative to petroleum and coal
without adding to climate change or pollution that lasts for millions of years, or being expensive beyond return, or killing lots of birds, is difficult.
Until our population goes to zero.
Then efficiency will be left to nature.
Wigley's computer simulations indicate that a worldwide, partial shift from coal to natural gas would slightly accelerate climate change through at least 2050, even if no methane leaked from natural gas operations, and through as late as 2140 if there were substantial leaks. After that, the greater reliance on natural gas would begin to slow down the increase in global average temperature, but only by a few tenths of a degree.
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FRISH