A “world first” green savings bond from National Savings and Investments (NS&I) goes on sale today, giving people the chance to back the government’s environmental projects and join the fight against climate breakdown. But at 0.65% fixed for three years, the interest rate prompted widespread disappointment, with the MoneySavingExpert.com founder Martin Lewis labelling it “pants” and “paltry”. A rate of 0.65% is well below the return offered by the top-paying standard fixed-rate savings bonds. On Thursday it was possible to obtain a rate of up to 1.81% on a three-year bond, while Zopa and Atom Bank were offering 1.6% and 1.45% respectively over three years. “Someone investing £20,000 at 0.65% will earn £130 a year in interest with NS&I compared with the best-buy deal from JN Bank at 1.81% which pays £362 per annum – a difference of almost £700 over three years,” said Andrew Hagger, a personal finance expert at the website MoneyComms. The new bonds can be bought online from today – just days ahead of the Cop26 climate summit – and will be on sale for at least three months. The money invested will help finance green projects chosen by the government, which could include zero-emission buses, offshore windfarms and flood defences, and tree-planting and environmentally sustainable farming schemes. The bonds, announced by the chancellor, Rishi Sunak, in the spring budget, have a minimum investment of £100 and a maximum of £100,000. Savers’ cash cannot be withdrawn during the three years. The Treasury said it was the world’s first green savings product from a sovereign issuer. With NS&I, the government-backed organisation that offers premium bonds and other products, 100% of people’s money is guaranteed by the Treasury. Officials believe that with demand for environmentally-friendly investments growing, the bonds offer a way to generate both financial and environmental returns. But with speculation that UK interest rates could rise before Christmas and could hit 1% by next summer, savers may not rush to lock away their money for three years at just 0.65%. Hagger said: “I appreciate the government is looking to fund essential green projects, but at a time of raging inflation where consumers are being squeezed financially from all angles, I can’t see people rushing to hand their cash over to the government at such a heavy discount.” Sarah Coles, a senior personal finance analyst at investment firm Hargreaves Lansdown, said the rate was “such a disappointment”, and that NS&I was relying on savers who were willing to pay a price for going green with their savings. She added: “You can get 0.65% on an easy access account (with limited withdrawals) from Coventry building society, so it’s easy to wonder why you’d bother tying your cash up for three years for the same return.”