Off Grid Energy Storage:

Shell Foundation & Grantham Institute | By: Various Authors | GPE – December 23, 2017:

Executive Summary: Over the past decade, there has been a rapid increase in the deployment of solar home systems, and rural utilities coupled with electrical energy storage devices, enabling off grid access to energy and power stability. Developments in the electric vehicle industry have led to significant innovation in energy storage technologies, increasing cycle life at the same time as reducing costs. However, selection of rapidly developing energy storage technologies for remote deployment has been a question of great debate in terms of technology selection and optimisation for performance, lifetime and costs.

This report presents outcomes from a series of interviews with organisations providing off grid energy solutions, on their storage technology choices, challenges and opportunities.

These include insights on technology availability and supply chains, realised costs of storage solutions, performance of technologies and how these compare to manufacturers’ specifications, and the environmental impact of storage technologies.

Building on these insights, the report provides recommendations on how technology choices could be improved in the future, both from an individual company and from a regulatory perspective, and the impacts of future technology developments upon these choices.

Key Takeaways:

1. Energy storage technologies vary in terms of cost, cycle life, charge / discharge rate and environmental impact. Different business models and applications favour different technologies.
2. Lead-acid (PbA) and lithium-ion (Li-ion) batteries are the dominant storage technologies in all but the largest systems. Lead-acid batteries are mature and costs are relatively stable, whereas Li-ion battery costs are falling rapidly. In addition, Li-ion batteries have higher cycle life, and can charge / discharge faster than PbA batteries.
3. Companies using PbA batteries may switch to Li-ion batteries within the next 5-10 years as Li-ion becomes more cost competitive. Generally, applications requiring batteries of lower energy capacity switch first, owing to lower capital required per product.
4. PbA and Li-ion batteries are expected to remain dominant for at least the next ten years, but, other, less mature storage technologies such as Redox Flow Batteries (RFBs) are beginning to be commercialised and could be promising in the future.
5. Amongst Li-ion battery chemistries, those with lithium-iron-phosphate (LFP) cathodes are favoured owing to their safety and high cycle life in off-grid applications, in addition to their availability at relatively low costs from manufacturers in China and absence of toxic cobalt. However, quality of cells varies between manufacturers, and higher cost offers no guarantee of higher quality.
6. Li-ion batteries with nickel-manganese-cobalt (NMC) anodes, favoured in electric vehicle (EV) applications due to higher power and energy densities, could also be promising, particularly as costs fall and performance improves due to the scale-up of the EV market. But safety of such Li-ion chemistries in off grid applications has been questioned.
7. Thermal storage technologies, including thermal batteries, could become increasingly important at higher levels of energy access – particularly for agricultural refrigeration.

Key Recommendations:

1. There have been efforts to characterise the quality, cost and performance of different technology products in the off grid storage market, but greater quality and safety assurance, with the establishment of related standards, is required to enable appropriate, cost-effective and safe technology and product choice. This should extend to battery management and other battery electronics systems.
2. Measures to support the adoption of less mature technologies such as RFBs, which have been tested but not widely deployed, would help establish such technologies, enabling particular applications to benefit from their attributes.
3. Managing the environmental impact of storage technologies, particularly at end-of-life, represents a major gap. More detailed, effective and widespread regulation on end-of-life procedures, alongside supporting the emergence of a greater number of reputable, high quality and high safety recycling companies, would improve practice in this area.

To read full report – please click here.