150 W/cm2? Energy from Waste Heat Revolution

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Most of the energy from combustion processes such as an automobile's engine, is lost as heat. It seems a lot of waste to pump or dig fuels from the ground, only to lose most of the energy to the atmosphere as waste heat. Consequently, around the world engineers, scientists, and technologists are scrambling to find better ways to re-capture the huge mass of energy that is going missing every year.

Thermoelectrics is a growing and revolutionary method of redeeming waste heat to electricity -- analogous to photovoltaics except converting heat to electron flow rather than light. Brian Westenhaus brings us up to date on Nextreme Thermal, a company at the forefront of efficient thermoelectric conversion.

The thermoelectric field is gathering momentum and increasing efficiency. Many manufacturers are attending to this technology, as it requires no moving parts so the durability and miniaturization prospects look quite good.

For many heat producing power generation kits the excess heat is a nuisance, expensive to dispense with and money simply lost into things like rivers, the atmosphere and simply radiated away warming anything nearby which can be even more expense. From huge power installations generating electricity to automobiles thermoelectric on to microelectronics, thermoelectric conversion should find welcoming places. In the U.S. and Europe automakers from GM to BMW express enthusiasm for the technology to add to the electric output and reduce fuel requirements.

...The breakthrough product seems to be the Thermal Copper Pillar Bump (CPB) design that has applications in electronics where the technology can be used to cool and recover heat back into power. A highly desired goal is application in PC data centers where the operating costs for power to cool the electronics exceeds the power to process the data.

How good have they managed to get? A temperature difference of 60ºC has been achieved across the 60 µm (0.06 mm) high Nextreme CPB by running an electrical current through it. The Nextreme CPB demonstrated maximum power pumping capabilities exceeding 150 W/cm2. When subjected to heat the Nextreme CPB has demonstrated the capability to generate up to 10 mW of power per bump.

150 W/cm2 . . . That seems like a lot of power from a differential of 60ºC. Things are coming along faster than I had expected. _NewEnergyandFuel

Here is another look at the growing field of thermoelectrics, from Brian Wang.

More efficient retrieval and use of waste heat amounts to an energy revolution in its own right. Consider it but one more important piece in the puzzle problem to provide abundant energy to the growing needs of the future.

Cross posted at Al Fin Energy

At NextBigFuture, Brian Wang discusses methods of converting low temperature waste heat into usable energy. One of the methods discussed is the Ener-G-Rotors (Schenectady, NY) rankine cycle approach which instead of using a turbine for energy recovery, uses a gerotor (internal gear motor) instead.

Ener-G-Rotors' technology is based on the Rankine cycle, in which heated fluid flowing through a tube heats a pressurized fluid in a second tube via a heat exchanger. The second tube is a closed loop; the so-called working fluid flowing through it (a refrigerant with a low boiling point, in the case of Ener-G-Rotors) vaporizes and travels into a larger space called an expander. There, as the name would imply, it expands, exerting a mechanical force that can be converted into electricity.

Instead of turning a turbine, the expanding vapor in Ener-G-Rotors' system turns the gerotor, which is really two concentric rotors. The inner rotor attaches to an axle, and the outer rotor is a kind of collar around it. The rotors have mismatched gear teeth, and when vapor passing between them forces them apart, the gears mesh, turning the rotor. _TechnologyReview

Anyone with the least exposure to fluid energy will recognise the internal gear pump/motor as relatively inexpensive, but far from frictionless, and not nearly as durable as a well maintained turbine. Ener-G-Rotors claims to have made their gerotor virtually "frictionless" and therefore extremely durable. If so, it would be a significant advancement in cost reduction for this type of heat recovery.

New Hybrid Cycle Steam Engine Runs on Glycerol

Here is more information on the Cyclone external combustion engine that is set to power ten 1-MW electric generators. I call it a "hybrid" cycle engine, because it has features belonging to Rankine, Carnot, Diesel, and Stirling cycle engines.

The parties' plans are to power these industrial generators using a glycerol-based synthesis gas produced through Florida Syngas' proprietary plasma process called GlidArc™. Glycerol, the waste product of the bio-diesel industry, is a hydrogen rich, carbon neutral gas with its only waste products being hot water and useable heat. Under the agreement, Florida Syngas will design and build the synthesis gas converters, and Advent Power Systems will develop the engines and generator sets utilizing Cyclone's patented engine technology. Development of the equipment will be co-located in both Grant and Coconut Creek, Florida.___Source

The primary components of the engine include a condenser, steam generator and the requisite valves, cylinders, pistons, pushrods, main bearing, cams, and camshaft. Ambient air enters the engine through the intake blower, which circulates it through the condenser. According to Schoell, the flat-plate condenser �looks like a set of stacked record albums where air goes around the outside of the discs while the vapor on the inside is spun.� It is then directed through heat exchangers, and the air is pre-heated, enters the steam generator, and is mixed with atomized fuel that is also spun in the centrifuge.

...The power output is controlled by a rocker arm and cam design that opens and closes a needle valve in the head. This introduces high-pressure, high-temperature steam into the cylinder and provides the expansion force necessary to drive the pistons. Because it relies on the expansion of the fluid and not the expansive capacity of the fuel to create power, the Cyclone engine is fuel independent.___Autofieldguide

Whereas the old steam engine wasted most of its thermal energy (as much as 90%), the Cyclone Engine is highly efficient due to reheat and regeneration that recycle more than 30% of the heat generated from burning fuel. The engine operates at supercritical pressure (3,200 PSI) and temperature (1,100 degrees F) which makes the superheated steam behaves like a fluid rather than a gas so improving efficiency and making for a more compact engine. The overall thermodynamic efficiency is in the range of the Diesel engine (30-36%). The main advantages are: its capacity of using a wide range of fuels - gasoline, diesel oil, ethanol, kerosene, powdered coal, natural gas, etc.; continuous and complete combustion of fuel, creating less emissions than current gasoline or diesel powered internal combustion engines; high torque at start (700 ft/lb) which eliminates the need for a clutch and gearbox, simplifying the project and cutting down on power losses in transmission; the working fluid, water, is used to lubricate the engine, what avoids the long-standing problem of steam engines, the contamination of lubricating oil by water.___Wikipedia

Using glycerol-derived syngas for fuel is reasonable at this time, since glycerol is an inexpensive byproduct of biodiesel manufacture.

The Florida plans for 10 cyclone driven 1-MW generators, combined with the plasma syngas operation, demonstrates yet another "energy from garbage" approach. Forida appears to be in the vanguard of the advanced energy-from-garbage industry. That is unfortunate from the viewpoint of tourists who were hoping to see huge mountains of landfill dotting the Florida landscape in the near future. At this rate, Florida will be importing half the world's garbage before long--to use as fuel.

Cyclone Power Technologies

More Information on Cyclone engine operation

Combined Heat and Power Biomass, More Biofuels

Combined Heat and Power (CHP) is a highly efficient form of power production. One such plant in Denmark that utilises biomass in its fuel mix meets the heating demands of 200,000 homes and the electrical demands of 1.3 million homes.

Avedore 2, inaugurated in 2002, made the green switch successfully and is now a set of superlatives: it is the world's largest biomass power plant as well as the cleanest and most efficient cogeneration power station. It meets the heating demands of 200,000 households and supplies electricity to over 1.3 million homes (Denmark has a population of 5.47 million). The green plant covers more than 20% of Eastern Denmark's needs - the most densely populated region of the country - and supplies 570MW of heat to Greater Copenhagen's district heating system. The combined heat and power efficiency comes in at a whopping 95%.
___Source

A new type of external combustion engine that will burn biomass-based syngas, is developing 10 1MW generators for the Florida market.

The companies' plans are to power these industrial generators using a glycerol-based synthesis gas produced through Florida Syngas' proprietary plasma gasification process called GlidArc. Glycerol (glycerin), the waste product of the biodiesel industry, yields a hydrogen-rich, carbon neutral gas with its only waste products being hot water and useable heat.....Cyclone engine technology is a new type of external combustion engine but relies on established technologies, such as those used in gas turbines, diesel engines, and steam engines. The engine is based on the Schoell cycle, a cross between a Rankine, Diesel and Carnot cycle engine (schematic, click to enlarge). Its main characteristic is that it will burn any combustible fuel, including biomass and municipal waste. Advent Power Systems claims the engine has other advantages:

* Clean burning – Provides complete combustion and a very clean exhaust
* Efficiencies comparable to diesels, when all required subsystems are included
* High horsepower to weight ratios – about a 2.5 to 1 advantage over full diesel systems.
* Low noise, vibration, and infrared signatures.
* Large range of sizes possible – from 1 KW up to over 1 Megawatt.
* Facilitates conversion to a range of synthetic fuels, including biomass.
* Provides an ideal power source for hybrid and conventional vehicles.
* Does not require a radiator, water pump, oil pump, complex fuel injection, or catalytic converter, reducing cost, weight, space and increasing reliability.___Source

I am particularly curious to learn more about the external combustion engine mechanism, that will be driving the 1 MW generators. The global glycerol glut from world biodiesel production should provide inexpensive fuel, and the ability to convert to biomass fuels, there should be no "peak fuel" scenario for these facilities.

Finally, China and Brazil are said to be collaborating on development of bio-ethanol from a newly discovered type of cassava--a sweet cassava mutant.

China currently cultivates around half a million hectares of cassava, of which 200,000 are destined for ethanol production. The People's Republic chose cassava as one of its future biofuels crops, because it is considered to be an industrial plant, and not a food crop. According to Wenquan Wang, researcher at CATAS, cassava has gained importance because of its low environmental footprint and because it has a well established industrial presence. "For 30 years, cassava was a staple for many Chinese people, later it became a crop for animal feed, and nowadays 60% of the entire harvest is destined for the industrial production of starch, 20% goes to ethanol and the remainder is turned into pig feed."

However, China's cassava ethanol initiative is mainly based on starch rich varieties. Together with Brazil it is now looking at introducing the sweet varieties instead, which demand less costly and complicated conversion steps.

Source

I wonder how the sweet cassava alcohol yield will compare with the yield from sugar cane? Regardless, it has to be a much higher yield than from maize.

OTEC: Ocean Thermal Energy Conversion

Ocean Thermal Energy Conversion (OTEC) is at the center of the Energy Island concept. OTEC was invented by Frenchman Georges Claude in the 1920s. The idea is simple: use the approximately 20 degrees C difference in temperature between the deep ocean and tropical surface ocean to drive a heat engine. Besides producing megawatts of electric power, the byproducts of the process include clean freshwater for drinking and growing crops, and plenty of air conditioning.

There are two basic versions of the technology. The first operates in a "closed cycle", using warm surface water to heat ammonia, which boils at a low temperature. This expands into vapour, driving a turbine that produces electricity. Cold water from the depths is used to cool the ammonia, returning it to its liquid state so the process can start again.

The "open cycle" version offers the added benefit of producing drinking water as a by-product.

Warm seawater is introduced into a vacuum chamber, in which it will boil more easily, leaving behind salt and generating steam to turn a turbine. Once it has left the turbine, the steam enters a condensing chamber cooled by water from the depths, in which large quantities of desalinated water are produced - 1.2 million litres for every megawatt of energy.

A 250MW plant (a sixth of the capacity of the new coal-fired power station that has just won planning permission in Kent) could produce 300 million litres of drinking water a day, enough to fill a supertanker. Using electrolysis, it would also be possible to produce hydrogen fuel.

Telegraph


The map below displays the ocean area where the temperature difference between surface waters and the deep ocean is great enough to allow large scale economical OTEC . By placing a site close to an arid coastline, an OTEC energy island could make a huge difference in quality of life--by providing reliable electric power, plentiful fresh water for drinking and crop irrigation, and chiller-based air conditioning.
Energy island based seasteads could also provide a nucleus for burgeoning aquaculture--based upon the nutrient-rich deep ocean water routinely pumped into the OTEC generator.

I anticipate that most Energy Islands and seasteads would be owned by corporations, and would fly a national flag. It is likely that some seasteads--or group of seasteads--would choose to declare independence, to become their own independent country. That is when things would start to become interesting.

Hunting Buried Treasure

The surface of the earth hides much treasure, buried below. Oil, gas, precious metals, scientific findings, and potentially valuable geothermal heat. How nice it would be to have the ability to look beneath the earth, to find all the treasures there.

High-resolution images that reveal unexpected details of the Earth's internal structure are among the results reported by MIT and Purdue scientists in the March 30 issue of Science. The researchers adapted technology developed for near-surface exploration of reservoirs of oil and gas to image the core-mantle boundary some 2,900 kilometers, or 1,800 miles, beneath Central and North America.

"Rather than depth, it's the resolution and lateral scale that are unique in this work," said lead author Rob van der Hilst, professor of earth, atmospheric and planetary sciences (EAPS) and director of MIT's Earth Resources Laboratory. "This could lead to a new era in seismology and all the other deep Earth sciences. In addition, our new expertise may be able to improve how we look for oil in or beneath geologically complex structures such as the Gulf of Mexico salt domes," he said.

The technique--akin to medical imaging such as ultrasounds and CAT scans--led to detailed new images of the boundary between the Earth's core and mantle. These images, in turn, help researchers better understand how and where the Earth's internal heat is produced and how it is transported to the surface. They also provide insight into the Earth's giant heat engine--a constant cycle of heat production, heat transfer and cooling.

Source

A recent seismic survey in California located a 50 million year old impact crater three miles in diameter, buried 4300 feet deep under sediment.

A better understanding of geologic structure would help to utilise the geothermal energy trapped in dry hot rocks.

Finally, should the a large comet or asteroid hit the planet before humans learn to utilise the lebensraum available in the greater solar system, it might be necessary to establish large scale communities underground, powered by nuclear energy. It might even be necessary to build these communities as "generation ships", suitable for long term survival until the surface of earth became livable again.

It is, after all, our planet. Understanding it better--inside and out--is simply smart thinking. Preparing for all contingencies.

Here is A Good Approach to the Energy Problem

The Kohkala technology recovers waste heat (or uses solar heat) and produces electricity as well as hot water and space heating from low temperature heat that is usually wasted. This approach will be a boon to homes and small industries that have not been able to utilise cogeneration technologies due to the low level of heat produced. This is one approach to small scale power generation that can be widely applied--especially when combined with newer geothermal technologies. Making use of relatively low temperature energy is like snatching usable energy from the jaws of the monster entropy.

Here is more from Kokhala:

Kokhala's solution uses a unique heat-to-electricity closed loop power cycle solution optimized to generate electricity from external heat sources above 120F. The heart of the EnergyCell® are two proprietary, oil-free variable speed positive displacement expander engines, optimized to efficiently convert the external heat into mechanical rotary power, and then into electricity. The modular components are designed to function in a compound thermal relationship such that a high temperature power cycle is optimized with working fluid circulates between 600F and 250F and a low temperature power cycle is optimized with a different working fluid circulates between 250F and 120F. Since the heat transfer and expansion occurs in a biphase mode, cycle efficiency are optimized and the heat exchangers are minimized. Each expander turns an efficient permanent magnet DC generator with a high turned down ratio. The residual heat from the low power temperature cycle is provide to heat domestic hot water and provide comfort heating for the facility. Based on principles of organic Rankine thermodynamics, the EnergyCell®. exhibit excellent efficiency, low acoustical and electrical noise, no polluting emissions, high reliability and long life.

Source.

Hat tip Peswiki.

Solar Energy--Even When the Sun Is not Shining

The rate of solar energy intercepted by the earth is about 5,000 times greater than the sum of all other energy sources, but less than 0.5 percent is represented in the kinetic energy of the wind, waves and in photosyntheticstorage in plants. The amount of the solar energyintercepted by earth is only one thousandth of one millionof the total released energy in the sun. Source.

Using photovoltaics, you are limited to an average of six hours per day of usable energy production, minus time for bad weather. Often the periods of heaviest usage of energy are times that the sun does not shine.

One way around that problem is to place photovoltaic panels in earth orbit, well above the shadow of the earth. Generated power can be beamed to earth by microwave, and collected by large rectenna farms on the surface. Here is a link to a blog, Power From Space, devoted to this topic.

Another method is to collect the sun's energy while it shines, and store the energy for later use. Unfortunately, this method does not collect nearly as much energy as the orbiting solar satellites, but the sun provides so much extra energy to earth that it will suffice. What is the best method of storing solar energy?

Batteries are not a good choice for utility-scale storage, because the energy density of batteries is too low, given their high cost and short lifetimes. The only possible exception in terms of current battery technology would be redox flow cells. In five or ten years, redox flow cells might be ready for the challenge.

Electricity is hard to store at the present time. But energy comes in many forms, and is convertible from one form to another. With present technologies, the best form of solar energy storage is thermal storage--heat. Below are several links providing more information about thermal storage.

Wiki
Purdue
Open Directory Thermal Energy Links
Ionic Thermal Storage
Dissertation on Phase-Change Heat Storage Systems

Thermal storage is a type of energy averaging. Rather than being forced to use all the six hours of sunlight at one time, the energy can be stored and used over the entire 24 hour period. Solar Ponds are one form of thermal storage. OTEC is another, and in that sense the ocean itself could be thought of as a huge thermal system.


Phase change thermal storage will eventually become an important strategy for energy conservation in residential and commercial building construction. An incredible amount of useful heat can be stored inside materials that undergo phase changes at appropriate temperatures. Utilities are experimenting with large solar ponds, phase change thermal storage, and other methods of using stored heat to drive a heat engine, to generate electricity over the entire 24 hour period, adjustable to demand.

Eventually, for electric power purposes, redox flow cells and other newer electrical storage methods will eliminate the need for thermal-electric conversion losses. But humans need heating and cooling to live and work comfortably, and in that sense thermal storage will always be useful for human buildings and infrastructure.