Critics of renewable energy sources like wind and solar claim that they are inefficient, unreliable and need to be backed up by coal and gas, writes David Elliott. But we have the technology to match green power supply and demand at affordable cost without fossil fuels – by deploying the ‘smart grid’, using ‘green gas’ made from surplus power, and raising energy efficiency. In his new book, Green Power Balancing, Elliott looks at the issues and concludes that there are many ways in which large contributions from variable renewables can be balanced – so it’s not a major problem. Moreover it may not cost too much. Indeed some of the balancing options can save money. For example smart grid systems can shift demand peaks to times when green energy is cheaper, while supergrids can shift green power from where it’s available and cheap to where its scarce and expensive. A recent ‘Smart Power’ study by the UK government’s National Infrastructure Commission claimed that such an approach might actually save £8 billion per year by 2050. At present most grid balancing is done by ramping fossil fired gas plants up and down, but in future some of these can use green fuels, including storable green gas produced using surplus electricity from wind and solar. The variable output from renewables, with too much being produced sometimes too little other times, can thus be turned from a problem into a solution. Several studies suggest it can. For example, one high renewables 2050 UK scenario, produced by Poyry consultants, had a large wind capacity in place, 198GW, this along with other renewables, being sufficient to meet most demand most of the time. The wind plants would generate around 120 TWh surplus energy over the year, nearly enough, if converted to hydrogen, to meet low-wind shortfalls at other times. The remaining gaps, including during peak demand times, could be easily dealt with by a bit of pumped hydro storage, demand side adjustment and supergrid imports. For longer term balancing, the Pyory scenario also retained around 34GW of gas fired plants, just over 11% of the total capacity on the grid. A more recent study, by the Energy Research Partnership, came up with a similar figure- there would be a need for around 12% of fossil input to balance a notionally 100% renewable system. However, as a study by the UK Pugwash group argued, if more renewable capacity was added, this residual fossil gas input could be replaced by green gas produced by the extra surplus and from biogas sources. So assuming demand has also been tamed, with a major energy saving programme, problem solved.
Ecologist 6th May 2016 read more »
It is technically and economically feasible to run the US economy entirely on renewable energy, and to do so by 2050. That is the conclusion of a study last year in the journal Energy & Environmental Science, authored by Stanford scholar Mark Z. Jacobson and nine colleagues.
VOX 3rd May 2016 read more »
A senior executive at Western Australia network operator Western Power says that high levels of renewable energy pose no great technology challenges to the grid, although it may change the way that networks are managed.
Renew Economy 6th May 2016 read more »