Global renewables review

As the new annual REN21 global review illustrates, renewables are booming most places, supplying 28% of global electricity, with PV solar especially lifting off fast, including, at last, in Australia and, crucially, Africa, north and south.  In all, there’s over 1TW of PV in place globally. The scale and reach of some of the new projects planned is very dramatic. For example, there is a proposal for a 20GW PV array in north Australia which would  send power to Singapore. Meanwhile, wind also continues to boom, offshore especially, with ever larger, taller devices, as well as floating units. There are some huge projects planned. For example, up to 20GW of offshore wind has been proposed by Denmark for islands off NE Europe, including 10GW linked to an artificial ‘hydrogen island’ in the North Sea, on its part of the Dogger Bank. Denmark also plans two other offshore wind-based energy islands for the North Sea and Baltic Sea with the potential for some hydrogen production. 

Clearly hydrogen is becoming a regularly featured energy vector, in part since it can be stored in a range of ways and the cost of producing it by electrolysis using renewable power is falling. However, although, batteries still rule the roost, at least for short-term storage,  there are also other energy storage options, some of which may offer advantages in the newly emerging flexible energy systems, including heat stores of various types and some intriguing gravity based systems. 

Certainly, as the use of renewables expands demand for long-term storage will rise. The US National Renewable Energy Labs say that seasonal storage technologies will become ‘especially important’ for 100% clean energy systems, for storing excess generation in the spring and fall and shifting energy supply to the summer and winter. It claims that over 400 GW of seasonal storage capacity, such as combustion turbines fuelled by renewably derived hydrogen, would be needed for 100% clean energy.

 There are economies and efficiencies of scale for both generation and storage, but it does not all have to be large scale. PV especially lends itself to local use and PV-battery systems are popular, and there are also some interesting new ideas for hybrid PV-biomass powered domestic systems.  For the moment though, large scale floating PV arrays are one of the more interesting new developments, since they can reduce evaporation from reservoirs and the cooling effect of floating on water improves PV cell efficiency in hot climates significantly. They also avoid land use, with one option being to use hydro reservoirs, possibly with some pumped storage for grid balancing.

Meantime, looking to the longer-term future, new and updated studies of the long term global potential of renewables are emerging.  Prof. Mark Jacobson and his team at Stanford University have produced an updated set of 100% wind, water and solar energy 2050 scenarios covering 145 countries.  The new study makes use of new data on technology costs, which, amongst other things, allows them to balance their proposed energy mix more with batteries: ‘ four-hour batteries are concatenated here to provide both long-duration electricity storage and substantial instantaneous peaking power. Because battery costs have dropped dramatically and because four-hour batteries are now readily available, it is now justifiable to include a larger penetration of batteries than in the previous studies’. So less demand response and very long term storage is needed, reducing costs.

The paper concludes that ‘The full transition should occur no later than 2050, but ideally by 2035, with no less than 80% by 2030’, political will, not technology or costs, being the key factor. In the new 2050 scenario, on-shore wind is up (by 9 percentage points) on their previous scenario, utility PV is 10 pts up, roof top PV16 pts down, offshore wind 2.7 down, hydro 0.5 down.  

Jacobson also notes that, overall, it’s a low cost approach, because ‘a clean, renewable energy system uses much less energy than does a combustion-based energy system. In fact, worldwide the energy that people actually use goes down by over 56 percent with an all-electric system powered by clean, renewable sources. The reduction is for five reasons: the efficiency of electric vehicles over combustion vehicles, the efficiency of electric heat pumps for air and water heating over combustion heaters, the efficiency of electrified industry, eliminating energy needed to obtain fossil fuels, as well as some efficiency improvements beyond what is expected’.

So end-use efficiency, substitution and the elimination of energy used in mining fossil fuels, vastly cuts demand, which can all be met by wind water & solar. Similar views have emerged  from the 100% renewables global and national scenarios produced by LUT University in Finland, who have also produced some updating material in the form of a comparison of their models with other high renewables studies around the world, noting some divergencies in approach.  Modelling issues apart, they focus on a study of Bolivia and conclude that Sun Belt countries like this ‘ have the opportunity to develop highly decentralised fully sustainable energy systems that do not require large interregional transmission networks, with solar PV, batteries and electrolysers providing the foundation of such energy systems’. 

While northern areas may be less blessed, they will usually have the advantage, if you can a call it that, of being able to replace old large inefficient fossil fired plant and associated  infrastructure. So the north-south differences may balance out over time. The cost of local grid upgrades may be significant in some locations, but, however done, the social and economic savings from avoiding fossil fuel use could be substantial everywhere.  And globally, switching from coal to renewable would yield savings equivalent to around 1.2% of global GDP p.a. until 2100, according to a study from Imperial College London.

There are of course possible down sides. For example, all technologies use materials and some may become scarce, while, for most, extracting ores can be ecologically damaging. The hunt goes on for new reserves and for less damaging extraction routes and lower impact alternatives. One alternative is of course to use less energy, and the debate over down-sizing demand and degrowth generally rolls on. It is clear that we can’t continue to have growth of resource use on a planet with finite resources and limited ecological carrying capacity, but the debate over the relative merits, impacts and possibilities of technological and social change continues.  

The various green energy technologies are getting better, with costs still falling, and visions of what might be done are clear, but, with fossil fuels still fighting back hard and demand still rising, that may not be enough to secure a sustainable future.  The new REN 21 review says that, with modern renewables only supplying around 12.6% of total final energy, renewable power additions must triple to meet net zero climate targets, but warns that ‘the slow progress in energy conservation, energy efficiency and renewables prevents the transition away from fossil fuels that is necessary to meet global energy demand and reduce greenhouse gas emissions. A structural shift in the energy system is increasingly urgent’.