The world population is growing, as is energy demand, and we have long been able to see the consequences of climate change caused by the world’s consumption of fossil resources. The IEA reports that global demand for energy was around 18 terawatts (TW) in 2013. This corresponds to 18,000,000 megawatts. Demand is expected to rise to around 25 TW in 2040. This means that our carbon emissions will be approximately 40 gigatonnes (GT) a year—compared to 32 GT in 2013.