Battery storage for utilities will be the high-cost alternative. Other methods are being proven at scale, and will ultimately eliminate the competition for batteries.
The most mature of these is "stored hydro", in which water is pumped up to a dam reservoir. Obviously this depends on having a dam not too far away, a ready source of water below it, and enough spare generating capacity there to take up the load when needed. Ramp-up is near instantaneous.
In places with deep mine shafts, a similar gravitational storage method is practical: suspend a heavy weight (hundreds or even thousands of tons) at the top of the shaft, attached to cables that turn a motor-generator as they unwind. This has the advantage that it may ramp up to full power in seconds, and the available energy is limited only by the depth of the shaft. Obviously this depends on availability of long vertical mineshafts, but there are very many of these worldwide. The tech involved is all 19th-century, so these only need construction. When excess / cheap power is available, the weight is hoisted back up.
Another is underground compressed air. (This may be combined with the above, pumping air into the same mineshaft, as is being done in one pilot installation.) This, also, relies only on 19th-century technology. Roughly half of the energy stored in compressed air becomes heat, so efficient use requires good heat insulation. Earth serves as excellent insulation. Power is extracted by exhaust through a turbine; existing turbines from older generation schemes may be repurposed. Ramp-up is fast. The reservoir must be charged up for some time in advance to be able to get maximum power out at sudden need. Several examples of this are being demonstrated.
Air liquification is a perhaps surprising alternative. It relies on mature 20th-century technology; there have long been numerous industrial uses for liquified air. For maximum full-cycle efficiency, heat extracted from the air is also banked. A GW-scale plant is under construction in Scotland, and a 50 MW demonstrator is breaking ground in Chile. An advantage of air liquification is that the storage capacity is limited only by the number of cheap insulated tanks built, which may be added to at leisure.
The above are the immediately available alternatives. Efficient hydrolysis of water to produce hydrogen has obvious industrial importance, and it may eventually displace other methods, as there is no upper limit to the useful amount of hydrogen that may be usefully produced from surplus generating capacity, even after local tankage is full.
The most mature of these is "stored hydro", in which water is pumped up to a dam reservoir. Obviously this depends on having a dam not too far away, a ready source of water below it, and enough spare generating capacity there to take up the load when needed. Ramp-up is near instantaneous.
In places with deep mine shafts, a similar gravitational storage method is practical: suspend a heavy weight (hundreds or even thousands of tons) at the top of the shaft, attached to cables that turn a motor-generator as they unwind. This has the advantage that it may ramp up to full power in seconds, and the available energy is limited only by the depth of the shaft. Obviously this depends on availability of long vertical mineshafts, but there are very many of these worldwide. The tech involved is all 19th-century, so these only need construction. When excess / cheap power is available, the weight is hoisted back up.
Another is underground compressed air. (This may be combined with the above, pumping air into the same mineshaft, as is being done in one pilot installation.) This, also, relies only on 19th-century technology. Roughly half of the energy stored in compressed air becomes heat, so efficient use requires good heat insulation. Earth serves as excellent insulation. Power is extracted by exhaust through a turbine; existing turbines from older generation schemes may be repurposed. Ramp-up is fast. The reservoir must be charged up for some time in advance to be able to get maximum power out at sudden need. Several examples of this are being demonstrated.
Air liquification is a perhaps surprising alternative. It relies on mature 20th-century technology; there have long been numerous industrial uses for liquified air. For maximum full-cycle efficiency, heat extracted from the air is also banked. A GW-scale plant is under construction in Scotland, and a 50 MW demonstrator is breaking ground in Chile. An advantage of air liquification is that the storage capacity is limited only by the number of cheap insulated tanks built, which may be added to at leisure.
The above are the immediately available alternatives. Efficient hydrolysis of water to produce hydrogen has obvious industrial importance, and it may eventually displace other methods, as there is no upper limit to the useful amount of hydrogen that may be usefully produced from surplus generating capacity, even after local tankage is full.