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Renewable energy capacity will expand thanks to new and improved technology like floating wind turbines – but some fossil fuels are here to stay, says Matt Rooney, engineering policy adviser at the IMechE:
The growth of solar and wind will be one of the biggest global stories up to 2030. Most offshore wind turbines to date have been built in shallow waters, but floating turbines offer cost reductions and deployment in deeper waters.
Solar panels have already become lighter and more efficient, but there is still scope to go further. Conventional panels only use visible light, but researchers are developing panels that will use a larger band of the electromagnetic spectrum to be even more efficient.
The challenge will be how we integrate these variable sources of electricity. They are weather dependent so require increased energy storage and smart demand management to ensure voltage and frequency.
Pumped hydro is the dominant way to store excess electricity, but its ability to expand is limited by geography. Battery technology, however, has improved incredibly over the past decade or two – energy densities are higher, charging times are faster and costs are coming down. But batteries are mostly suited for fast bursts of electricity rather than large-scale, long-term storage.
Liquid-air energy storage is an exciting new technology, and a 5MW facility was recently announced near Manchester. It would use low-cost electricity to cryogenically cool air and store it in liquid form. At times of high electricity demand, the air would be released to drive a turbine and generate electricity. Like pumped hydro, liquid air could store large amounts of energy for long periods. Unlike hydro, however, you could build these facilities anywhere. The main downside is that the round-trip efficiency is likely to be lower.
Flywheels, pumped heat storage and supercapacitors will be other options, while hydrogen has huge potential.
Smart grids will become increasingly important in managing demand. This could mean using electric-vehicle batteries to export electricity to the grid at times of high demand, or smart appliances that switch off to take stress off local networks.
There is an interesting idea of using interconnectors to export electricity over large distances, but I’m not sure about the proposal to use the solar potential of Africa to power Europe. The technology is sound but for geopolitical reasons I don’t think it will happen at a large scale.
The expansion of nuclear energy will primarily be driven by China. They have an ambitious programme of deployment of conventional reactor designs and a range of R&D projects to test more ambitious technologies. They also have begun a pilot project to use a nuclear reactor to heat homes in the city of Jiamusi.
Elsewhere, particularly in western countries, the focus has begun to shift towards small modular reactors (SMRs). In the UK the government has given a Rolls-Royce-led consortium £18m to develop its SMR design. The Department for Business, Energy and Industrial Strategy has also provided funding to eight companies through the advanced modular reactor programme, to conduct feasibility studies into innovative designs like the stable salt reactor, and even Tokamak’s small fusion reactor.
One thing that is not going away is natural gas. We have plentiful supplies, driven by fracking expansion in the US in particular, and it is used across our energy system. That is going to make decarbonisation difficult, but does incentivise the development of hydrogen as a low-carbon alternative.
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.