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Off Grid Energy Independence
Posted on May 01, 2018 by Dr Peter Harrop

Unexpected renewables advances

Recent progress in renewables has bordered on the surreal. At ICREN Barcelona recently we were invited to consider those giant wind turbines sweeping 200 meters of sky. Up there the wind is stronger and more consistent and that size of turbine is more efficient. Further, such high wind is stronger at night - off setting solar when it is dead, something not the case with wind at lower levels. The giant turbines are by far the largest stressed structures made by man, "with Europe in the lead" so what is one of their next key enabling technologies? Dr Bottasso named something small from the world of self-driving taxi-buses - LIDAR - because it gives a precious ten seconds advance notice of what wind is about to hit.
How about underwater photovoltaics? It has recently been shown to work in shallow salt water ponds that can now do three things - make salt, make drinkable water and make electricity, the water keeping the photovoltaics cooler and therefore more efficient, compensating for its partial obscuration.
Not reported in the press, there is a strong move against those massive banks of batteries currently being purchased for grids and minigrids. With chemical processes you store the end product, be it clean water, hydrogen, ammonia or whatever, not electricity half way through the process. Indeed, we heard of photoelectrochemical processes that go straight to the chemicals using sunshine. It can be done with nasties mercury, cadmium or lead chemistry but tin is the relatively safe chemistry chosen.
Where continuous electricity is needed, stored water power is in some giant wind turbines. It was nice to know that some offshore wind now gets an amazing 60% capacity factor and we were advised that offshore wind would go well with wave power on the same platform at sea, giving even better continuity, less battery. One opinion was that tidal power, because it is using such consistent and strong power compared to wind will win over wind in the end. However, for now, "for every two steps forward tidal power makes, wind makes ten." Wave power has no consensus on even the basic optimal designs and certainly no standardisation for economy of scale but it is also progressing.
Just when all the talk is of better grids - smart, green - there is a lot of evidence of large facilities, even cities going energy independent, zero emission. An airport in India, three new cities in North America, a Saudi high rise office block and the Tesla Gigafactory for example, all entirely zero emission but usually by a choice of two from hydro, wind and solar to give redundancy and less need for storage. Prof Morante advised that "grid defection" will make sense widely in 10-15 years and minigrids are a "fantastic solution" for South America today. However, some countries are still in the dark ages. Catalonia had to sue the Spanish Government to allow home solar to grid connection and we learnt that in some countries it is still illegal to have a microgrid battery in your house.
Power electronics was not forgotten. For an electric car it will become more of the cost and function than the battery. For wind power without storage we were told it is 15% of cost and for solar without the battery 10% so there are parallels here. Indeed, wide bandgap semiconductors are now the name of the game in all three cases.
For more information see the IDTechEx report on Off Grid Zero-emission Electricity
Dr Peter Harrop

Authored By: Dr Peter Harrop


Posted on: May 1st 2018