odysseus2000 wrote:Many in the storage field argue that grid storage has to be by battery and vehicle to grid, but there are a number of prototypes of compressed gas storage that look to be lower cost, more reliable, to have longer life times and quicker to construct.
It depends on what scale you're looking at. At the moment compressed air looks the cheapest for durations of a few hours to a couple of days, but current thinking seems to be that by 2030 the size of its niche will be squeezed by batteries on the short side and hydrogen on the long duration. It'll still have a niche, but perhaps rather smaller than its fans think. And it is somewhat geographically constrained like pumped storage - in this case it will be fighting for access to salt caverns against hydrogen storage.
According to a recent RenewableUK EnergyPulse table, UK battery storage is currently :
2.4GW in operation
2.5GW under construction
15.2GW awaiting construction (presumably grid connections are one factor for delay, plus supply chain bottlenecks)
16.7GW in planning
15.1GW pre-planning
So 20.1GW with planning permission or later stage, and 31.8GW at the planning/pre-planning stage - 51.9GW is more than the current UK peak load! But it's all relatively short-term, what we need is batteries with longer duration rather than discharge capacity, stuff like the
Form iron-air batteries with 100-hour duration (even if their round-trip efficiency ain't great).
I've often mentioned the
Ruhnau & Qvist paper which looked at German weather patterns over 35 years and concluded that for the absolute worst case, once-in-a-generation Dunkelflaute in that time, Germany would need 36 TWh of electricity, which given the round-trip inefficiencies would amount to 56TWh of storage.
They were more interested in the weather side of things so their economic/technology model is relatively simple, they came up with a 100% renewable Germany (they say peak load is 105GW, whereas other sources put it at about 80GW, UK is about 50GW) having 300GW of variable renewable generation of which 284GW was split pretty much equally between solar, offshore and onshore wind. They see 72GW of storage charging capacity and 81GW discharge capacity (ie 77% of peak), of which 77% was hydrogen-fired CCGT and 19GW of other storage. They see hydrogen accounting for 97.8% of the stored energy, with 1,300GWh from pumped hydro and just 59GWh from batteries. As I say, their model is relatively simple, I guess you can substitute "any cheap long-term storage" for "hydrogen" and "any cheap short-term storage" for "batteries".
I've also mentioned
the recent report from HMG's advisors, which admittedly only looked at an "average" year but in more detail on the grid side in 2035. In particular I suggest people look at
the separate report they received on "flexibility" (ie storage and related issues). Which sees 2% of electricity coming from gas (without capture, essentially legacy CCGTs) in 2035 and :
The provision of short-duration flexibility from ≤4hr grid storage technologies and [demand-side response] demonstrate rapid growth, more than doubling from 17GW in 2025, to 41GW in 2035...Batteries are expected to experience growth in the 1-2 hours duration capacity levels until 2030, and 4-6 hours thereafter... the role of medium- and long-duration grid storage solutions is expected to be limited, with only existing pumped storage and small levels of CAES on the system by 2035. Instead, alternative sources of flexibility such as hydrogen storage and low-carbon dispatchable capacity are considered to be more cost-effective...
The level of demand shifting in 2035, 50GWh per day or 4% of total demand, is significant and demonstrates the impact that demand response programs can have on the energy storage requirements of the grid. However, the emergence of this smart and responsive demand is heavily dependent on the adoption rates of electric vehicles and heat pumps, as well as consumer engagement in these areas.They talk about grid upgrades from p56.