1. Alternatives to WindTP

2. Preface
WindTP integrates energy storage into a power-transmission system for wind turbines.
Of course there are alternatives ...

3. Contents Just do without energy storage Use standalone energy storage
Integrate storage with Wind in other ways
WindTP review in light of the above

4. Contents Just do without energy storage Use standalone energy storage
Integrate storage with Wind in other ways
WindTP review in light of the above

5. Who needs Energy Storage?
To operate well, the electricity system needs flexibility. Energy storage is only one of several possible ways to provide this flexibility.
Massive interconnection of power systems will help, for example.
So, too, would extensive demand-side response.
Smart Meter
Water Heater

6. Who needs Energy Storage?
Time-zones and weather patterns span distances of thousands of km!
Interconnection over these distances has a high cost.
The occurrence of daylight tends to cause us to synchronise our

7. Contents Just do without energy storage Use standalone energy storage
Integrate storage with Wind in other ways
WindTP review in light of the above

8. Standalone Energy Storage?
Standalone energy storage takes electricity from the grid and puts it back there.
Wind variation is slow! Slow variation => large amounts of stored energy for a given power.
Irish wind power and demand recorded in 2011
Energy storage is expensive! Batteries >$200/kWh until at least 2022(?) Example: 1MW wind turbine, 2 days storage ~ 50MWh ~ $10M.

9. Standalone Energy Storage?
Apart from batteries, there is also …
Pumped hydro energy storage, PHES
Compressed air energy storage, CAES
Pumped thermal energy storage, PTES
Liquid air energy storage, LAES
Flywheel energy storage
Varieties of gravitational energy storage other than PHES
Issues:
Location dependence (PHES and CAES)
Costs of power-conversion machinery (affects all)
Cost effectiveness can depend on huge scale (PHES, CAES)
Round-trip losses can be large (20%  50%) (LAES, PTES esp)

10. Contents Just do without energy storage Use standalone energy storage
Integrate storage with Wind in other ways
WindTP review in light of the above

11. GIES with Wind Gearbox Install a compressor in wind turbine nacelle ?
Gearbox still needed because natural speeds so different.
Gearbox
Comp-ressor
Blade
Hub
‘Costs extremely high.
e.g. WO Eric Ingersoll (behind General Compression) (Early patent from GC). GC now diverted to EIEO storage and merged ..
Direct drive air compression in nacelle is impossible – huge swept volume.

12. GIES with Wind
Direct air compression – but not in nacelle ?

13. GIES with Wind Pump water directly? Great idea – except for 2 things:
limited to 10m of “suction”
Wind is typically strongest at the top of a hill, not at the bottom!
Long mechanical transmissions quite expensive.
There are some indirect possibilities with cable drives or hydraulics.
You still need a large natural pumped-hydro type resource

14. GIES with Wind Convert rotor work directly into heat??
(US 2012/ A1) Filed June Owned by APPLE Corporation.
Concept study of wind power utilizing direct thermal energy conversion and thermal energy storage Toru Okazakia, Yasuyuki Shiraib, Taketsune Nakamurab Renewable Energy, 83, Nov. 2015
Mr. Carnot teaches why this has limited possible efficiency

15. GIES with Wind Use “spare” rotor work to drive a reversible heat pump?
Differential Gearbox
Hub
Blade
Differential Gearbox
Hub
Blade
Generator
Generator

16. Contents Just do without energy storage Use standalone energy storage
Integrate storage with Wind in other ways
WindTP review in light of the above

17. WindTP Review Now review what WindTP does!
Can be integrated with any new wind farm - anywhere
Uses one direct-drive machine to absorb all power from the wind turbine rotor – the primary compressor
Uses one (shared) expander-generator set to deliver electrical output power.
Uses one (shared) secondary-compressor (rated at 65% of collective power of primary compressors)
Has very low marginal cost for power-conversion kit
Only passes energy through storage that should pass through storage.
Has a high effective round-trip efficiency.

18. An Open Lecture, Nottingham, June 15, 2010
Thank you for listening
Sincere thanks to EPSRC for funding the work from which WindTP emerged.
An Open Lecture, Nottingham, June 15, 2010