"Negative emissions technologies" (NETs) that capture and sequester carbon dioxide from the air will need to play a substantial role in mitigating climate change in order to meet climate and economic growth goals. Unlike carbon capture and storage technologies, which remove CO2 emissions from big point sources like coal power stations, NETs remove CO2 from the atmosphere directly or improve natural carbon sinks. Storing carbon dioxide from NETs has the same effect on the environment and climate as preventing the emission of an equal amount of carbon dioxide. According to recent studies, installing NETs could be less expensive and disruptive than eliminating certain pollutants, such as a significant share of agriculture and land-use emissions and some transportation emissions. 'Negative Emission Technologies,' also known as 'Carbon Dioxide Removal,' or 'greenhouse gas removal,' may be required to remove more than 10 billion tonnes of CO2 per year by the end of the century. NETs will never be a complete alternative for decreasing emissions, but they may be effective in displacing some energy/emission intensive industries. A single NETs solution is unlikely to be scalable enough to address this need, hence a portfolio of techniques may be more practical.