The Statkraft solar park just outside Emmen, the Netherlands.
In an ideal world, the energy scarcity triggered by the war in Ukraine would serve as a wake-up call to accelerate the transition to renewable energy. However, it is far from clear whether green energy alone can plug the gap, and this has left Europe scrambling for alternatives, even more polluting ones. In the foreseeable future, power generation is likely to proceed along several diverse tracks, and instrumentation will play an important role in enhancing energy efficiency.
By James Chater & Madeline McNabb
Hard choices
“Ukraine or air conditioning?” This how a friend of mine starkly summed up the dilemma the world — and especially Europe — is facing as the war in Ukraine drags on. How determined are we to curb Russian aggression by phasing out imports of Russian gas? The question has huge economic implications and will also affect the pattern of energy consumption for years to come.
Assuming that European resolve holds, gas piped from Russia will disappear, but it will only be partly replaced by LNG. Tough and difficult choices will have to be made. For instance, Germany, which is committed to phasing out nuclear power, will keep its last three plants open for the time being and will have to rely more on its polluting lignite coal industry. Several European countries are turning to coal to plug their energy gap.
There is no magic bullet. Each energy type comes with its own advantages and disadvantages (see Table 1).
Hydro
Hydroelectric power is still the largest source of renewable electricity and is expected to grow by 50% by 2040. Most of the growth is occurring in Asia, which also hosts the largest ever project, China’s Three Gorges Dam. The IEA expected hydro’s share of renewable electricity to fall below 50% in 2024 as that of wind and solar increases.
Solar
Solar and wind are the fastest growing renewables, mainly because prices have plummeted over the years, and they are relatively easy to install. (Prices ticked up in 2022, breaking a long-term trend, but they are still competitive with fossil fuels as these too have risen in price.) However, both are vulnerable to weather fluctuations (the wind does not always blow; the sun does not always shine), so can work effectively only in tandem with efficient storage systems (see box below).
Growth in solar PV has been spectacular. It can be installed flexibly to fit with existing superstructure: on roofs, as roofs, floating on water, as paving, etc. Technical innovations continue to improve efficiency; for instance, by combining a perovskite solar cell with a textured silicon solar cell, an efficiency of 29.2% can be achieved. One of the most ambitious PV projects is the planned 1100MW project in Port Açu and additional locations in Brazil, to be built by a Chinese consortium.
Less flexible and more complicated to site is concentrated solar power (CSP). This is a much smaller market than PV and uses more expensive technology, but it has the advantage of integrating energy capture and storage, often using molten salt as a medium. Spain and the USA are the market leaders. The largest current such project is the UAE’s Noor Energy 1.
Energy Storage
Solar and wind power are intermittent forms of energy and cannot function properly unless storage is used to capture excess energy at times of abundance and release this energy when demand exceeds supply. The oldest form of energy storage occurs in hydro energy, when water is pumped uphill then released to drive a turbine. Gravity is also used in other devices, and other alternatives include compressed air and cryogenic air. The fastest growing storage device is the lithium-ion battery, also used in electric vehicles. But lithium is expensive, bulky, causes fires and, being sourced mainly in China, is subject to geopolitical risks. So scientists are researching alternatives, though no clear leader has emerged.
Another fast-growing storage device is hydrogen, which is “green” if produced by electrolysis fuelled by renewable energy. It can be stored and transported in compressed or liquefied form.
Wind
The second renewable “star” is wind energy, with onshore additions from 2021-26 set to increase by 26% compared to the period 2015-20.
As turbines get larger (China’s MingYang Smart Energy having just set a record at 242 metres of diameter), larger economies of scale are achieved. China accounts for around half the onshore additions since 2015, with Europe and the USA in second and third place.
The offshore sector is smaller but also expected to grow rapidly. It has at least two advantages over land-based wind power: steady wind sources and synergy with tidal/wave energy and seawater desalination (for example, TechnipFMC and Bombora’s project combining wave and wind power). Another advantage is that floating wind turbines are likely to gain importance as a way of generating electricity in deep water. Most of the projects up to now have been Europe-based, concentrated in the North Sea and the Irish Sea (the Equinor/SSE Dogger Bank, BP’s Morgan and Mona 3 GW project; the Norfolk Offshore Wind Zone), but offshore wind investments are now taking hold in the USA (which aims to install 30 GW by 2030), Vietnam, Taiwan, S. Korea and Japan.
Wave and tidal
Wave and tidal energy exploits waves and tides to capture energy. It could equally be called “lunar gravity” energy. Various technologies exist, but high costs have meant that progress has been slower than with solar and wind. It has taken until 2023 for the first commercial wave energy project to come online, off Póvoa de Varzim in Portugal. From 2023-24 the market was expected to accelerate, with growth of 33.2% between 2021 and 2028. Apart from Portugal, countries pursuing wave/tidal energy include Chile, the UK, USA, Australia and S. Korea.
Geothermal
Another energy type that has lagged because of costs but holds great promise is geothermal power. Advantages include a steady heat source and synergy with combined heat and power (as in the Eden Project in Cornwall, UK). Up to now, the number of sites has been limited to those where geothermal heat lies close to the earth’s surface, but a new project by MIT could change this. Quaise, an MIT start-up, plans to drill 12 miles into the earth using fusion drilling, which it is hoped will make a near limitless source of energy more easily accessible.
Biofuels
Biofuels have become a well-established energy sector, with many fossil-fuel power stations retooled to process biofuels as well as numerous greenfield projects. Creating energy from biomass is controversial (see Table 1 above). Despite the environmental dangers, however, there is a place for it, and recent solar biofuel projects, which mimics photosynthesis to create biofuels, may answer some of the ecological objections.
Instrumentation and control systems in power generation
Accurate instrumentation and measurement technology optimize power generation systems. As diverse energy sources — ranging from hydro, wind, and solar to geothermal and biofuel — play an increasingly important role in power generation, precise monitoring and control systems are even more indispensable.
Temperature sensors: These are crucial in every power generation method, from the combustion chambers in coal and gas plants to the heat exchangers in nuclear and geothermal systems. In renewable sources like solar and geothermal, temperature measurements help monitor system performance, ensuring optimal efficiency. In battery storage systems, sensors that monitor temperature are essential to prevent overheating, which can significantly reduce a battery’s lifespan and performance.
Pressure and flow meters: Used extensively in steam and gas turbines, as well as in the transmission of natural gas or hydrogen, these instruments ensure that systems are running within safe parameters. In hydroelectric and wind energy systems, flow meters are essential for monitoring the movement of water and air, helping adjust operations for maximum power output. In hydrogen storage, pressure sensors help maintain optimal conditions for storage and transport.
Level sensors: In hydro, geothermal, and biomass-based plants, level sensors monitor the levels of water, steam, or biofuels, ensuring that systems operate efficiently and safely without overflows or interruptions in fuel supply.
DCS and SCADA: Distributed control systems (DCS) and supervisory control and data acquisition (SCADA) provide real-time data, enabling operators to make informed decisions that optimize efficiency, reduce downtime, and prevent accidents. Especially in wind and solar, SCADA systems allow operators to adjust turbine operations based on weather forecasts, load predictions, and energy storage levels. This is particularly important in intermittent energy sources where variability must be managed to ensure a stable energy output.
As the energy landscape continues to evolve, new instrumentation technologies are being developed to enhance the efficiency and safety of power generation. For instance, advanced sensor technologies such as fiber optics and wireless sensors are being explored for use in power plants. Additionally, the integration of artificial intelligence (AI) and machine learning (ML) with instrumentation systems is enabling predictive maintenance, better fault detection, and system optimization in real-time.
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