Walker Architects & Energy Storage

Jan. 11, 2010 - PRLog -- CO2 Energy Storage/Power Regeneration System

Introduction
Continued use of fossil fuel remains problematic in the context of global warming, the population explosion and rapid nuclear proliferation, given anticipated oil production shortfalls. These three parallel vectors drive the need for accelerated change in energy policy and technology. Circumstance mandates Energy alternatives, Energy Conservation and Energy Storage Systems.
Alternative energy systems embody the best strategy to reduce additional emission of CO2, however achieving long term energy storage remains the critical core capacity to implementation.
Energy storage is the storing of some form of energy that can be drawn upon at a later time to perform work. CO2 stored under pressure, in a tank or sequestered underground in a suitable geologic formation, is a reservoir of potential energy.  Once captured and reservoir created, the CO2 needs to be closely monitored, maintained and secured for centuries to come.
My concept, is to “bottle surplus electricity and CO2 at the same time and in the same place. Earthquake and volcanic activity is not compatible with CO2 sequestration strategies. The central idea is to store electrical energy generated in summer for use in winter. Generated electrical energy and thermal energy are stored as liquid or supercritical CO2 in the form of pressure, temperature and energy embodied in the phase change of liquid or supercritical CO2. On demand that stored energy can be recovered from the temperature, pressure and phase change expansion as the working fluid converts instantaneously back to a gaseous state. That energy is used to drive engines and generate electrical power. The CO2 can be sequestered in underground vaults or contained in manmade tanks as a working fluid. An energy storage cycle applicable to large and small scale.

I declare and have claimed as my intellectual property an innovative method that uses CO2 or other suitable substance with suitable properties to store energy for long periods of time for later use. This method would store power from; all energy sources; hydro electric, solar photovoltaic, solar thermal, wind turbines, or any other source of electrical power used to drive the pumps & compressors and thereby store energy in the CO2 reservoir as potential energy for later regeneration as electrical energy. This new technology, process & method is an energy storage & power regeneration system. This submission describes a new way to develop and use both the existing energy generation infrastructure and new renewable alternatives to more efficiently combat climate change by reducing greenhouse gas emissions.

There has been invented a storage/power regeneration plant. Captured CO2 is first sequestered as a reservoir of liquid or supercritical CO2 in a geologic formation or in a pipe or a tank. The cycle begins when the reservoir is used to store additional energy. A compressor driven by surplus electrical power from any alternative or conventional energy source is used to inject CO2 , increasing reservoir pressure and recycling the CO2 in the system. The working fluid expands in the reservoir and absorbs additional pressure and heat. Liquid or supercritical CO2 is then pulled up an extraction well from the reservoir into any suitable engine type at supercritical pressure. Pressure, heat and flash vapor phase change reaction all occur as the embodied energy is released creating an explosion which drives the engine to efficiently operate and mechanically regenerate electrical power. The CO2 is captured in a suitably large low pressure chamber then re-compressed in the energy input phase and returned to storage in the reservoir as liquid or supercritical CO2. The storage/power regeneration plant may be combined with large central-station power plants or scaled to fit small residential scale power plants.

There has been invented a generally applicable method and energy cycle for storing power in summer for use in winter, consisting of an underground reservoir that is created by pumping liquid or supercritical carbon dioxide or other suitable fluids hereafter called the working fluid, through an injection well into a suitable geologic formation such as a depleted natural gas or oil well or other natural formation or a suitable manmade structure. For this application locations in seismically active areas where earthquakes and volcanic activity is common are not suitable locations. The working fluid is then allowed to heat up and absorb the ambient geothermal energy and expand. Surplus (input) electrical energy from conventional or renewable energy power plant(s) is thereafter used to further pressurize the working fluid. Small scale applications may be constructed using lower pressure and temperatures ranges for example with liquid carbon dioxide as the working fluid. Larger application may use supercritical carbon dioxide as the working fluid using much greater pressures and temperature ranges.

A fully encapsulated closed-system power plant is then constructed that operates and is maintained at suitable high pressure by application of (input) electrical power and uses the working fluid in a cycle to drive pressure-type gas turbine(s) and associated generator(s) for the purpose of regenerating the output electricity, from which process the exhaust, now in a gaseous state and at a reduced pressure and temperature, is passed through heat-recovery and into the low pressure chamber(s). The gas is pulled by compressor(s) from the low pressure chamber compressed and condensed back into a liquid or super-critical state, by using the surplus (input) electrical energy and known and established industrial processes. The compression may involve multiple stages and is hereafter referred to as the compressor train, which includes heat related technologies.

The working fluid is now recycled again and again in a continuous cycle scaled in general to store energy in summer for use in winter.  In a liquid or supercritical state the working fluid is moved through heat exchangers into the injection well that extends down into the reservoir contained by a suitable geologic formation, such as a natural subterranean cavity or a manmade structure. Within this subterranean containment the working fluid is used to store the energy of surplus electrical power from renewable or conventional electric power sources. In this part of the cycle the working fluid also absorbs additional pressure and also absorbs additional heat energy, such that the working fluid achieves higher super-critical parameters having elevated super-critical temperature and pressure.

When a demand for additional electrical power exists the working fluid is channeled upwardly from the subterranean reservoir through extraction well(s) designed to withstand elevated super-critical temperatures and pressures, the impurities from subterranean gas, water, or minerals and other solids are filtered and separated by known industrial methods from the working fluid prior to entering the turbine(s) inlet.

Said turbine(s) is designed to fit, local conditions, extract the maximum electrical power generation from the working fluid and may where warranted include heat exchanger(s) and multiple energy conversion stages which will be hereafter referred to as the turbine/generator train. Heat recovery technologies will be used to enhance efficiency. The energy embodied in the working fluid by the temperature, pressure and the phase change from supercritical to gaseous form is converted to mechanical energy by the turbine(s) portion of the train and used to drive associated generator(s) in the turbine/generator train, with maximum possible efficiency for the local condition. The resulting electrical power is then conditioned and transmitted by existing conventional means in response to the demand load.  Multiple extraction wells are preferable in large power storage applications.

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