Long Duration Energy Storage LDES Reality: Markets in 28 Lines, Technology Appraisals, Roadmaps, Escape Routes 2025-2045

The race is on. From your solar house to your grid power, increasingly solar is the winner with wind a close second globally, both needing storage of increasing delay as their percentages rise. For 2025-2045, Long Duration Energy Storage LDES has arrived meaning eight hours or more of subsequent discharge at full rated power. That compensates solar dead at night and where lithium-ion stationary storage becomes far too expensive.

An independent report is required, appraising the many technologies, current successes, potential and latest research. It must consider escape routes reducing LDES need and the realistic forecasts that result. Welcome the new 560 page, commercially-oriented “Long Duration Energy Storage LDES Reality: Markets in 28 Lines, Technology Appraisals, Roadmaps, Escape Routes 2025-2045”.

Primary author Dr Peter Harrop advises that providing LDES for your solar house is some way off, but LDES at MW to GW levels and 10-24 hours duration is a huge immediate demand. Projects and commitments already involve six very different LDES technologies, mostly off-grid or capable of being off-grid. Gigawatt LDES levels mostly serve grids using two other LDES technologies so far, both needing major earthworks, more to come.

Vital questions are answered including:

• LDES need after recognising escape routes such as nuclear, geological and ocean power with minimal intermittency, new wider grids spanning time and weather zones, hydrogen economy?
• 2025-2045 forecast lines by size of unit, region, 11 technology categories plus roadmaps, SWOT appraisals, parameter tables?
• Can grids be served with GWh LDES not needing large earthworks and delays? How? When?
• Big differences between small, medium and large LDES. For example, beyond-grid purchasers need small footprint (high energy density or safely stackable), low up-front cost, but grid needs low levelised cost of storage.
• Which technologies have the big advantage of adjusting power and capacity separately?
• Big breakthrough: Which technologies will economically compensate both short-term demand changes and long-term supply changes with one unit?
• Technologies ahead for small, medium and large power? For example, two very different types of underground water storage are being constructed as forms of Advanced Pumped Hydro Storage APHES. Watch iron redox flow batteries.
• Detailed predictions: Levelised Cost of Storage, capital cost, duration, life, operating costs, safety, toxigen and precious metal issues.

The report is the most comprehensive and up-to-date. It mentions over 100 companies in 11 chapters with research advances, company progress through 2024, 19 SWOT appraisals. There are 7 technology comparisons (17 parameters).

The Executive Summary and Conclusions (30 pages) is sufficient in itself, with 20 key conclusions, new infograms, roadmaps and those 28 forecast lines 2025-2045.

Chapter 2. “LDES need and design principles” (20 pages), covers energy basics, escape routes from LDES such as nuclear, geothermal and ocean power, vehicle-to grid and some grids now spanning many weather and time zones. Here the conclusion is that LDES will still be a massive market but perhaps half of what some vested interests predict. It then covers LDES needs and introduces the technologies.

Chapter 3. “Hydrogen and other chemical intermediary LDES” (53 pages) focuses almost entirely on hydrogen. The others are uneconomic . Even hydrogen is highly contentious with very strong opinions either way enabled by a lack of data. Will there be a hydrogen economy permitting marginal pricing? Will the small Energy Vault above-ground hydrogen LDES being erected tell us much about the optimal giant underground hydrogen LDES?

Chapter 4. “Pumped hydro: conventional PHES” (17 pages) describes how this traditional approach, three types, has long achieved LDES that also provides short term response and has life on 100 years or more. There are plenty of potential sites but few will be approved. See the latest parameter comparison, improvements ahead such as low carbon, stronger concrete, SWOT appraisal then move to the reinvention of pumped hydro for where there are no steep cliffs.

Chapter 5. “Advanced pumped hydro APHES” explains how pumping water into sprung rocks underground and pumping saltwater into caverns underground are now yielding encouraging data. Interesting ideas such as pumping heavy liquid up mere hills and water into sub-sea bladders are seeking meaningful funding.

Chapter 6. “Compressed air CAES” is very important, being the only technology beyond pumped hydro that the US DOE 2024 report finds can drop to a levelised cost of storage of under $50/MWh by 2030, something the world needs with its headlong adoption of wind and solar. See ten CAES companies appraised, 2024 research,, SWOT, predictions in 63 pages.

Just behind CAES in cost reduction potential is redox flow batteries. Many companies move into LDES versions for some grid applications but mostly off-grid or capable of being off-grid. They have small footprint, safely stackable, no  massive earthworks and potentially very long duration and life.

Chapter 7. “Redox flow batteries RFB” therefore takes138 pages to profile 44 RFB manufacturers and developer, give the usual appraisal of 17 parameters and SWOT report but also make sense of a flood of academic progress in 2024. Why are iron and hybrid versions rapidly gaining share but not competing? Performance potential in 2035 and 2045?

Chapter 8. Solid gravity energy storage SGES (26 pages) looks at Gravitricity lifting weights in mines but not promising LDES, various small experiments and ideas. Contrast Energy Vault licensing Chinese companies to make giant versions, later likely to be LDES. See SWOT, parameter comparisons, projections, possible issues such as high capital and maintenance cost but good things too.  

Chapter 9. “Advanced conventional construction batteries ACCB” mainly covers metal-air, molten salt and metal-ion batteries ignoring lithium-ion because it is unable to compete on cost from 2025-2045 at LDES durations. Most have the problem of coupled power and capacity so you just have to buy more of them as demand rises for ever larger grid units. Few improve on the leakage current of  lithium-ion but one extreme is Form Energy being low in capital cost to compensate many weaknesses, attracting an eye watering $1.2 billion investment and the largest, longest duration grid LDES project beyond pumped hydro. Other ACCB are mostly best beyond-grid. They are very different, so see eight SWOT appraisals and many parameter comparisons, many academic advances in 2024 and routes forward. See eight families compared in eight columns  on one of the 54 pages.     

Chapter 10. “Liquefied gas energy storage LGES: Liquid air LAES or CO2” (21 pages) considers what is, in many respects, intermediate in parameters and benefits  making them part of the grid and beyond-grid market with some projects and funding but no major success as yet.

Chapter 11. Thermal energy storage for delayed electricity ETES (18 pages) assesses how joule heating of rocks or other solids then returning to electricity with steam turbines has led to many company collapses, failing to compete in efficiency, duration or much else. Contrast one large 2024 project using heat pumps, supported by 2024 academic research presented here.  Two other companies pursue a wild-card: incandescent storage temperatures, photovoltaically returning to heat when needed. See appraisals.