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Friday, June 26, 2015

Better concentrated solar power (CSP) stations

Concentrating solar thermal power stations convert as little as 25 to 30 percent of collected solar energy into electrical energy and need large thermal energy storage systems that add to the cost of construction.

Existing technology allows solar thermal energy to be converted into electrical energy with an effective efficiency of 90 percent and eliminates the need for thermal energy storage systems.

Burning hydrocarbons and carbohydrates - energy used and released

What the diagram represents is that 1 kilogram (2.2 lbs) of brown coal is decomposed into carbon monoxide and hydrogen by absorbing 5.54 megajoules of heat energy. 

The resulting carbon monoxide and hydrogen then releases 14.14 megajoules of heat energy when it combines with oxygen to produce carbon dioxide and water vapour.

The net heat energy available from burning this kilogram of brown coal is the difference between these two energy flows: 14.14 - 5.54 = 8.60 megajoules of heat energy.

Burning a kilogram of brown coal in a coal-fired power station allows a proportion of this 8.60 megajoules of heat energy to be converted to electricity.  Typically only about 40 percent is delivered as electricity: around 0.96 kilowatt-hours.

A different way of converting brown coal to electricity enables a far greater amount of electricity to be produced from each kilogram:
  • First each kilogram of brown coal is decomposed into carbon monoxide and hydrogen by absorbing 5.54 megajoules of concentrated solar thermal energy.  
  • Second, the resulting carbon monoxide and hydrogen releases 14.14 megajoules of heat energy when it combines with oxygen to produce carbon dioxide and water vapour in a gas power plant. Typically about 60 percent is delivered as electricity: around 2.36 kilowatt-hours.

The coal needed to produce 0.96 kilowatt-hours of electricity is reduced from 1 kilogram (2.2 lbs) to just 405 grams (14.3 ozs).

Saturday, June 20, 2015

Better concentrated solar thermal power plants

Concentrated solar thermal power stations using steam turbines or  compressed air turbines are less efficient than they could be.

This video describes the difference between steam turbine power plants and gas turbine power plants. Concentrated solar thermal power plants use the same technology without using fossil fuels as the source of thermal energy.

Steam power plants and compressed air turbines can only convert about 35% of the energy collected into electricity:
  • On the back end of the steam turbine the steam must be condensed back into water.  During this condensation process, heat is “rejected” up cooling towers and into the atmosphere, resulting in a loss of 30% to 40% of the original heat energy supplied to the system. More energy is then used in pumping the condensed water back into the boiler at very high pressure.

  • Compressed air turbines discard a large amount of energy collected in the exhaust flow out of turbine. More energy is used by the axial flow compressor that compresses air on input to the turbine. 
"Solutions" focus on methods to make use of the heat energy wasted by these engines. One often-used approach is to build an entire steam power station behind a compressed air turbine generator! This "solution" is known as a combined-cycle gas turbine or "CCGT" power plant.

For reasons that are not clear solutions that simply avoid the waste of thermal energy in the first place are overlooked.

Adding a high-efficiency compressor to the front of a conventional axial-flow air compressor and turbine generator allows the exhaust to cool to ambient temperature with no heat energy wasted.

Hicor technology achieves a more efficient compression process

Compression Basics

Compression Basics
The Hicor technology achieves a more efficient compression process by minimizing the temperature rise associated with compression, improving efficiencies over conventional compressors by 30% or more.
At its most basic, compression is a mechanism by which work is put into a fluid and results in an increase in pressure. Heat is also generated as a by-product of compression, which serves to make the process less efficient by turning some of the input work into heat instead of pressure. As the gas being compressed heats up further and further, the compression process gets less and less efficient.

Hicor’s technology achieves a more efficient compression process by minimizing the temperature rise associated with compression, improving efficiencies over conventional compressors by 30% or more.

Hicor’s proprietary compression technology provides a myriad of additional benefits as well, including fewer moving parts, less vibration and noise, and a variable pressure ratio. Finally, Hicor’s near-isothermal compression technology allows for compression ratios of 30 to 1 or higher, reducing system level complexity and resulting in lower capital and operating costs.

Positive Displacement Compression

The compression process can be displayed graphically, as in the pressure-volume (PV) plot shown below. The curves in a PV plot show how the pressure increases as volume decreases. For different compression processes, the curves will vary. The work of compression can be visualized as the area under the curve corresponding to a given compression curve.
All compression processes fall between two extremes: adiabatic, where no heat is exchanged with the outside environment and the energy put into the system remains internal; and isothermal, where energy is removed from the system in the form of heat and the temperature of the gas remains constant.

In practice, all compression processes fall somewhere between adiabatic and isothermal and are known as polytropic processes. To achieve a more highly efficient compression process, it is ideal to reduce the polytropic constant to as close to the isothermal process as possible, where the polytropic constant is 1.

The Hicor proprietary compressor design is capable of achieving polytropic constants as low as 1.06, improving efficiencies over conventional, near-adiabatic compressors by as much as forty percent.

Sunday, June 7, 2015

Selective blindness by coal mining companies

Coal mining companies deny the existence of technology that cuts the amount of coal needed to produce electricity.

Pakistan's first coal gasification plant will start generating low cost electricity from next year.

"The renowned scientist Dr. Samar Mubarakmand who is head of the Thar Coal Gasification Project  ...  was participating and Chairing the Clean Coal conference held here on October 23 and 24 to mark the World Clean Coal Week."

The Future of Asia: Be Innovative” - Speech by Prime Minister Shinzo Abe at the Banquet of the 21st International Conference on the Future of Asia

 Thursday, May 21, 2015
"...efficiency jumps remarkably through the use of the latest technologies for the combustion of gasified coal. ...
By utilizing gasification technology, brown coal, which until now has been regarded as unfit for coal-fired thermal power, will become a promising resource.
By introducing Japanese gasification technology to Mongolia, your vast resources of brown coal dormant in the ground of Mongolia will become a treasure trove."

Special Feature. Dawn of a New Era for Coal. Clean Production of Energy Using IGCC (Integrated Coal Gasification Combined Cycle)

Nakoso Power Plant, Joban Joint Power Co., Fukushima Prefecture, Japan
Nakoso Power Plant, Joban Joint Power Co., Fukushima Prefecture, Japan

"Integrated coal Gasification Combined Cycle (IGCC) is a coal-based power generation technology that achieves the twin objectives of reduced CO2 emissions and increased efficiency by "gasifying" the coal and then using a gas turbine and a steam turbine in a two-stage generation process.
MHI has been researching and developing this technology since the 1980s. It has accumulated numerous proprietary technologies and demonstrated their reliability primarily with test operations at an enormous IGCC demonstration plant. The demonstration plant quite successfully finished the test operations, satisfying all targets set. With its capabilities highly evaluated through the series of test operations, the decision was made to convert it to a commercial plant owned by a utility company and to commence commercial operations in June 2013. This marks the long-awaited practical application of a pioneering technology that will open a new era for the effective use of coal.
MHI has committed every possible technology towards the pursuit of the IGCC plant's efficiency. As well as combining gas and steam turbines with a highly efficient energy-converting gasifier, MHI also makes use of the discharged heat to avoid waste.
This mechanism delivers 10-15 percent better thermal efficiency than a state-of-the-art coal-fired conventional thermal power plant (ultra-supercritical coal-fired thermal power plant: USC). Because it can provide the same amount of power as a USC but using less fuel, it also cuts CO2 emissions by about 10-15 percent. This puts it on a par with oil-fired thermal power plants in terms of emissions.
The IGCC plant is a complex system that combines a gasifier, a gas turbine, a steam turbine and other interconnected equipment.
It is a testimony to MHI's advanced design and engineering skills that the plant succeeds in harnessing them together into an efficient and reliable working unit. Within just a year of its start, the Nakoso demonstration plant had racked up 2,238 hours of continuous operation.
This unparalleled achievement owes its speedy progress to the smooth interaction of the plant's various equipment.
IGCC is expected to spawn new technologies in the future. There is a real prospect of a MHI power plant achieving thermal efficiency of over 65 percent when it launches the J-Series gas turbine"