Associate editor Robin Hayes argues that G2P doesn’t have to mean methane as a fuel; cleaner alternatives are just around the corner.
A major argument lodged by the renewable energy lobby against gas to power (G2P) solutions is that methane is a fossil fuel and burning it contributes to global warming, albeit much less so than coal and with the world aiming for net zero for carbon emissions by 2050, embarking upon a G2P rollout will lead to what has been coined as stranded assets.
This phrase when applied to a CCGT (combined cycle gas turbine) power plant warns that investment can’t be justified as the equipment can no longer be used and may end up as a liability before the end of its anticipated lifetime as it fails to meet emission targets.
Alternative fuels
With so many advantages over coal fire power stations, it seems that the renewables brigade can only reiterate the stranded assets scenario occasioned by burning methane, but the manufacturers of these units have not been sitting on their hands – modern CCGT installations can run with near equal efficiency not only on natural gas, but diesel, biofuels, methanol, hydrogen/hydrogen blends and at least one firm is testing running its turbines on the ubiquitous NH 3 – ammonia!
The German government has recently issued a tender for the supply of 10GW of CCGT power, with the proviso that units must be capable of being able to run on hydrogen when available, as well as natural gas.
Research into a hydrogen economy is gathering pace almost daily with scientists addressing hydrogen’s inherent disadvantages of the huge amounts of electrical energy required to separate its molecules from water and the advanced materials required to convey and contain the gas within a closed system.
Many advantages
CCGT machines have many advantages: proven to be highly efficient both in terms of output, low maintenance and longevity. And they can be switched on and off more easily than a coal fired or nuclear station allowing flexibility of power delivery or even part load availability to top up base load when required or simply as ‘base load’.
Thermal efficiencies of up to 65% are commonplace especially with the more modern combined cycle gas turbines, less so with the older open cycle units that Eskom installed back in 2007/8 at Ankerlig and Gourika in Atlantis and Mossel Bay respectively. But they are still operating 16 years later, providing a vital lifeline in this era of loadshedding, giving a combined continuous 2 000MW plus to the grid even though they were originally intended for peak lopping, standby duties and in the case of Ankerlig, to provide power to Koeberg nuclear station should there be an emergency.
While critics rightly point out the huge cost penalty of running these units on diesel instead of natural gas, well, there was supposed to be a supply of gas to these two stations but that discussion is for another day as it opens another can of worms as to why we don’t have a fully functioning gas economy. The Gas Master Plan which is supposed to sketch out the fundamentals of a gas economy is still awaited, more than 10 years late…
Speed and meeting the need
In addition to their efficiency and longevity, gas turbine installations are quick to build – Ankelig and Gourika were up and running within two years of turning the first sod, unlike our recent coal fired stations Medupi and Kusile which are still not (and never will be) producing their designed output after 16 years of construction…not to mention the huge cost overruns. Our latest IRP 2023 stipulates that more than 6GW of CCGT power must be available by 2030, which is achievable if we start building now.
Some of the largest CCGT power plants in the world have outputs in excess of that provided by our largest coal fired stations – Russia’s Surgutskaya GRES-2 station has an output of 5 597MW while Japan’s Futtsu power station produces 5 040MW – well in excess of Medupi and Kusile’s ‘design output’ of 4 800MW.
Whether hydrogen or ammonia will be the energy salvation of the future remains to be seen or part of the mix, but technology and research is almost certain to overcome the emission problems that seem insurmountable today – remember the old proverb – needs must when the devil drives!
