Integrating Wind Turbine Generators (WTG’s) With GT-CAES (Compressed Air Energy Storage) Stabilizes Power Delivery With the Inherent Benefits of Bulk Energy Storage

The installed capacity of WTG’s in the US and worldwide, while impressive, suffers from a low capacity factor of 30% or less due to the variability of wind as the motive force. Installing larger wind farms to cover the deficiency of capacity results in high costs per delivered kW/hr. This begs for continued tax incentives to deliver “green” energy to the consumers. The full capability of the WTG is never realized as, at high wind speeds, some of the wind energy has to be “spilled” to maintain a smooth delivery profile. Technology improvements have not overcome the “wasted” capacity of these modern marvels except where Hydro or Pumped Hydro Storage (PHS) facilities are utilized. The Hydro power station can compensate for wind variability while PHS provides energy storage and delivers power during high demand periods. Wind Energy Storage results in a much higher capacity factor, in effect reducing the cost of delivered kW/hrs. The problem with this excellent solution is that the USA or the worldwide installation of WTG’s do not have such facilities readily available, are expensive to construct and difficult to permit in the USA. A readily available, cost effective alternative bulk-energy storage technology is ready for deployment throughout most of the continental USA. The GT-CAES concept incorporates a standard production GT with CAES technology and so covers a wide range of power production that can be matched to specific storage sites. During excess wind power production or nighttime wind, this power is used to drive air compressors to pump up or pressurize storage facilities such as salt caverns, deep aquifers (depleted natural gas wells). The stored compressed air is released to an air expander to recover the stored energy. The air to the expansion turbine is pre-heated to 950 to 1050 oF using the Gas Turbine exhaust energy recovered in a Recuperator (HRU). The low exhaust emissions are reduced further with SCR in the HRU. This paper will examine the early operating CAES concepts vs. the GT-CAES approach and will consider the economics of wind integration for lower costs of electric generation. Wind as a renewable resource would be able to deliver a larger percentage of “green” capacity with the ancillary power benefits of CAES such as Voltage Regulation, load following, spinning reserve, etc., not a feature of WTG’s. The patented GT-CAES system is described with examples of small and large installations using proposed projects with integration of Wind Energy.