But green solutions are not only needed in production. The waste disposal industry also offers opportunities for achieving more climate benefits. For example, the municipal waste disposal company Limeco in Dietikon, Canton Zurich, has been operating Switzerland’s first industrial scale power-to-gas plant since spring 2022. The sewage sludge from local wastewater treatment ends up in a bioreactor. The neighboring waste incineration plant supplies the electricity required to generate climate-neutral methane gas from the sludge. The purified gas is combustible and has the same properties as natural gas. It can therefore be used to heat homes, for example, or stored to generate climate-neutral electricity in gas-fired power plants when photovoltaics reach their limits at night or in winter.
The 10,000 to 15,000 megawatt hours of electricity already generated by waste recycling produce up to 18,000 megawatt-hours of “green” gas. Thomas Peyer of the Swiss municipal utility association Swisspower does the math: If all 30 waste treatment plants in Switzerland were to set up a power-to-gas plant of comparable capacity, together with the biogas already produced in Switzerland today, it would be possible to more or less replace the current import of natural gas from Russia.
From biowaste to biofuel
The Italian oil and energy group Eni (formerly Agip) is not quite as far advanced yet. But the company is operating a pilot plant that produces biofuel from organic waste at its research center in Novara, northern Italy. In pilot operation, this “waste-to-fuel” project uses mainly kitchen waste. Using what is known as hydrothermal liquefaction, the plant converts the moist biomass into a crude oil-like product under high pressure. This can be used, for example, as a crude oil substitute for ship propulsion or refined into higher grade biofuels. The efficiency is an impressive 80 percent. The process also generates up to 60 percent water, which in turn is used in other processes. On a larger scale, the “waste-to-fuel” method could also use sewage sludge, plant waste, or agricultural waste instead of kitchen waste. If this technology were to be implemented consistently throughout Italy, up to six million barrels of crude oil could be saved annually, according to operator Eni. In addition, the process puts waste that would otherwise have to be landfilled or disposed of elsewhere to a valuable and climate neutral use.
Floating wind farms are more efficient
Reducing dependancy on fossil energy and ending it completely as soon as possible is the goal of many other global projects and activities. One of these, for example, can be found 15 kilometers off the coast of Aberdeenshire, Scotland, where the “Kincardine Offshore Windfarm” – currently the largest floating wind farm in the world – operates. A total of six turbines around 200 meters high with 80 meter long rotors use the prevailing strong winds to produce up to 200 gigawatt hours of electricity per year. This amount is enough to supply more than 50,000 Scottish households with electricity. However, with water depths of up to 80 meters, this was only possible by mounting the wind turbines on so-called semi-submersible platforms, which were originally developed for oil and gas rigs. To withstand wind and waves, the platforms, arranged in a triangle, are partially filled with water. A pump system permanently balances this ballast between the three cylinders. In addition, the platforms are anchored to the seabed with cables. In any case, the wind blows more evenly and less turbulently over the sea than on land – which also means less material fatigue and damage to the wind farms.
Experts like Aaron Smith, Chief Commercial Officer of operator Principle Power, point out that up to 80 percent of the world’s sites suitable for wind power are located at sea – in places with comparable water depths. The world’s second largest facility of the kind, located in the Atlantic Ocean, 20 kilometers off the city of Viana do Castelo, Portugal, also makes use of the impressive high-tech design. The “WindFloat Atlantic” offshore wind farm has been supplying electricity to over 60,000 Portuguese households since July 2020.