wealth to provide an adequate return on investment for stakeholders. In the future, such an 'exo-economy' (off-planet economy) could possibly even serve as the first step towards mankind's cosmic ascension to a 'Type II' civilisation on the hypothetical Kardashev scale, in case such an ascension will ever be accomplished. However, it is yet uncertain whether an off-planet economy of the type specified will develop in due time to match both the volume and the output mix needed to fully replace earth's dwindling mineral reserves. Sceptics like Herman Daly and others point to exorbitant earth-to-orbit launch costs of any space mission, inaccurate identification of target asteroids suitable for mining, and remote in situ ore extraction difficulties as obvious barriers to success: Investing a lot of terrestrial resources in order to recover only a few resources from space in return is not worthwhile in any case, regardless of the scarcities, technologies and other mission parameters involved in the venture. In addition, even if an off-planet economy could somehow be established at some future point, one long-term predicament would then loom large regarding the continuous mining and transportation of massive volumes of materials from space back to earth: How to keep up that volume flowing on a steady and permanent basis in the face of the astronomically long distances and time scales ever present in space. In the worst of cases, all of these obstacles could forever prevent any substantial pushing of limits into outer space — and then limits to growth on earth will remain the only limits of concern throughout mankind's entire span of existence. Implementation Today, steady state economy is not implemented officially by any state, but there are some measures that limit growth and means a steady level of consumption of some products per capita: Phase-out of lightweight plastic bags that reduce consumption of bags and limit the number of bags per capita. Reducing the consumption of energy is a very popular measure implemented by many, called generally Energy Efficiency and Energy Saving. A coalition named "3% Club for Energy Efficiency" was formed with a target of increasing energy efficiency by 3% per year. According to the International Energy Agency, Energy Efficiency can deliver more than 40% of the reduction in Greenhouse-gas emissions needed to reach the target of Paris Agreement. In the 2019 UN Climate Action Summit, a coalition was created named "Action Towards Climate Friendly Transport"; its