The European Central Bank (ECB) has been paying interest to commercial banks in the euro zone, totaling around 360 billion euros since 2022. These payments are made without requiring anything in return from the banks. The ECB pays interest on the excess reserves that commercial banks hold with it, using a rate called the deposit facility rate, which was increased to 4% in 2023 to manage inflation. These reserves have grown significantly due to liquidity injected after the 2008 financial crisis and during the Covid-19 pandemic, with excess reserves estimated at between 3,000 billion and 4,000 billion euros in 2023. When the ECB makes these interest payments, it effectively creates money from nothing—similar to when it lends money to banks or buys financial assets. However, unlike those operations, which appear as assets on the ECB's balance sheet, interest payments do not add anything to its assets. This process is sometimes described as a "subsidy" created out of thin air. The ECB defends these interest payments as a necessary part of its monetary policy. However, some economists, including Paul De Grauwe and Yuemei Ji in a 2023 article, argue that this could be seen as a form of subsidy. They suggest that these funds could be redirected to support the ecological transition, which requires significant investment in areas such as energy efficiency, school and hospital renovations, and urban green spaces. These projects are often unprofitable and require subsidies, which are traditionally provided by governments through public debt or taxes. However, public debt limits and political challenges in raising taxes make this difficult, especially as growth needs may conflict with environmental goals. A "monetary subsidy" created by the ECB could offer a new source of funding for these essential projects without adding to public debt. From the ECB's perspective, this would be a complement to its existing methods of money creation, such as lending to banks or buying financial assets. For the recipients, this money would not be repayable, making it "debt-free" and suitable for financing non-profitable but necessary projects. Technically, there is no obstacle to a central bank issuing money without linking it to a loan or the purchase of an asset. However, this would result in a loss on the ECB's balance sheet. One could also imagine creating a non-claimable asset that reflects the ecological or social impact of the monetary subsidy. The funds would be directed toward specific, eligible investments, much smaller in scale than those used during financial or health crises. A small initial test, such as an emission of 0.5% of the euro zone's GDP, could be considered. A regulatory mechanism would ensure that this new money does not cause excessive inflation. The compatibility of such a monetary subsidy with the ECB's mandate would likely be a subject of legal debate. However, there is no explicit rule that would prevent it. Since the money would go to a network of sustainable development funds rather than directly to the state, it would not violate Article 123 of the Treaty on the Functioning of the European Union (TFEU).