“[Brown’s] ability to make a complicated subject accessible to the general reader is remarkable.”—Katherine Salant, Washington Post As fossil fuel prices rise, oil insecurity deepens, and concerns about climate change cast a shadow over the future of coal, a new energy economy is emerging. Wind, solar, and geothermal energy are replacing oil, coal, and natural gas, at a pace and on a scale we could not have imagined even a year ago. For the first time since the Industrial Revolution, we have begun investing in energy sources that can last forever. Plan B 4.0 explores both the nature of this transition to a new energy economy and how it will affect our daily lives.