Sustainable Energy for Wales: Tidal and Wind with Ammonia Storage

A guest post by Agustin Valera-Medina, Cardiff University, sharing the conclusions of the unpublished Master of Science Thesis by David Warwick-Brown for his M.Sc Sustainable Energy & Environment, 2017.

As part of the sustainable agenda of the UK, the government, research institutions, and various enterprises have looked for options to reduce the carbon footprint of the country while ensuring energy independence for several years. One of the alternatives has been to introduce the use of marine energy via the implementation of a barrage in the Severn Estuary or the development and implementation of tidal lagoons located around the Welsh coast.

Click to enlarge. Tidal Lagoon turbine technology, “The key elements of a conventional hydro double regulated bulb turbine.” Source: Tidal Lagoon plc.
From these alternatives, the tidal lagoon concept seems to be most feasible, as the cost is much lower than a barrage, although the current construction costs are still considerably high when compared to conventional power plants. Thus, hybrid technologies have been proposed to increase the produced energy, incrementing the power generated with a subsequent reduction of the levelized cost of electricity.

Wind energy, a well-demonstrated technology, has been considered to create hybrid systems capable of boosting the energy production of tidal lagoons with attractive economies of scale, because the foundations from the latter will serve as those of the former. This enables the production of off-shore wind energy, which is known to be greater than on-shore wind generation.

Hybrid tidal and wind energy systems will produce vast amounts of energy during off-peak hours that will require the use of energy storage technologies – the size of each proposed tidal lagoon ranges close to ~1.5 GW. Currently, companies involved in the development of these complexes are thinking of batteries, pumped hydro, and ammonia as the potential candidates to provide storage for these vast amounts of energy.

Thus, a recent preliminary study conducted by Cardiff University evaluated different sites where the concept of “Tidal + Wind + Ammonia Storage” could be developed while providing profitable scenarios.

For the study, recent details of tidal power generation were considered in combination with standard wind power production conditions based on the current wind profiles of the coast of Wales. The energy produced during peak and day-light hours was then directed to the grid, while off-peak power generation was used to produce clean hydrogen; this was analysed using data from highly efficient, newly developed systems by Siemens. Ammonia was then produced via iron- or ruthenium-based catalytic synthesizers; this analysis was performed using data generated by current studies of Oxford University, in which a combined electrolysis-catalytic system was estimated to have ~53% efficiency in the power-to-ammonia conversion. Finally, the ammonia produced would be sold at the current market price of ~£240 per tonne.

Click to enlarge. David Warwick-Brown, Analysing Potential Wind-Tidal Lagoon Hybrid Systems for Energy Generation and Green Ammonia Production in Wales: Fig. 4.8, Gross Profit of using “Tidal + Wind + Ammonia Storage” hybrid systems.
The results showed that the regions of North Wales and West Wales generate losses or extremely small profits, while the regions of South Wales, specifically Barry, Mumbles and Newport, showed highly profitable scenarios that now are being assessed by the companies working on these concepts.

Further works will be conducted shortly to provide data that correlates to novel commercial ammonia production systems, evaluating the efficient production of ammonia in combination with data of current energy consumption patterns in the UK. This will enable the economic analysis of off-peak energy storage in Wales, and support a proposal that seeks to set the precedent required for local, European, and industrial funding support.

The use of hybrid “Tidal + Wind + Ammonia Storage” systems will not only ensure clean energy production for Wales and the West of England, but will also enable the reduction of CO2 while utilizing surplus renewable energy for production of a chemical that can produce high profits in the current global market.

A guest post by Agustin Valera-Medina, Cardiff University, sharing the conclusions of the unpublished Master of Science Thesis by David Warwick-Brown for his M.Sc Sustainable Energy & Environment, 2017.

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