Alternative Energy

New Renewable Energy Alternatives Wind Energy - Nacelle

New Renewable Energy Alternatives

Wind Energy – Turbines

Most towers range from 131 – 328 ft.

The higher the tower the smaller the turbulence and the greater the wind speed.



Turbines are designed to rotate back and forth to respond to changes in wind direction, to ensure that the motor faces into the wind at all times.



Typically, turbines are erected in groups called, Wind Parks or Wind Farms.



Depending on the location, whether the winds are typically light or strong, the turbine is engineered to create either low levels or high levels of energy.


Wind Energy

Fastest growing energy sector

Though this source provides a small portion of the world’s power needs, its use increased 30% between 2000 & 2004


Wind Energy

wind power has provided 3.95% of the U.S.’s renewable electricity generation in 2004 – nearly 20 times more than solar power.


Wind Energy

Currently, wind energy production is geographically concentrated; only 5 nations account for 82% of the world’s wind energy output.

Germany, Spain, India, Denmark & U.S.

New Renewable Energy Alternatives Wind Energy

California and Texas account for 2/3 of the wind power generated in the U.S.

Denmark leads all nations in wind power. (Wind farms supply 20% of electrical needs).


Wind Energy – Offshore Sites

Wind speeds are typically 20% stronger over water than land, with less turbulence.

Popularity is increasing at these sites.



Though the costs are greater offshore, the stronger winds generate more electricity and more profit.



Denmark built the first offshore wind farm in 1991. Since, the power output from these farms has increased 43% annually.

New Renewable Energy Alternatives Wind Energy – U.S. Wind Projects (Megawatts)


Wind Energy – U.S. Offshore Projects Nantucket Sound off Massachusetts


Wind Energy – Benefits

1. Wind produces no emissions once the necessary equipment is manufactured and installed.

2. More energy efficient than conventional power sources.

New Renewable Energy Alternatives Wind Energy – Benefits

3. Wind turbines can be used on many scales, from a single tower for local use to fields of thousands that supply large regions.

4. landowners can lease their land for wind development.


Wind Energy – Benefits

5. wind energy involves up-front costs for the construction of turbines and the expansion of infrastructure to allow electricity distribution. Over the lifetime, it only requires maintenance costs.


Wind Energy - Downsides

1. We have no control over the winds.

2. Good wind resources are not always near population centers that need the energy, so the transmission networks will need to be greatly expanded.

New Renewable Energy Alternatives Wind Energy – Downsides

3. People generally oppose construction of wind farms too close to residential areas.

4. Turbines are generally located in exposed, conspicuous sites, and many people object to wind farms for aesthetic reasons.


Wind Energy – Downsides

5. Wind turbines are known to pose a threat to flying birds, which can be killed by the rotating blades.

(more birds are killed via tall buildings, towers and other human causes)


Geothermal Energy

Geothermal energy is one form of renewable energy that originates not from the sun, but rather from deep within the Earth.


Geothermal Energy

The radioactive decay of elements among the extremely high pressures deep in the interior of the planet generates heat that rises to the surface through Magma (molten rock) and through fissures and cracks.


Geothermal Energy

Deep in these regions, beneath the Earth’s surface, the energy heats groundwater, subsequently, natural spurts of heated water and steam will emerge from below.


Geothermal Energy

From this we get, Terrestrial geysers and sub-marine hydrothermal vents.

As a result of Iceland being formed from this molten rock, Magma, there exists tremendous geothermal heat in this region.


Geothermal Energy

As a consequence, Iceland has numerous geysers and volcanoes


Geothermal Energy

Geothermal energy is renewable in principle, but the power plants we build to use this energy may not all be capable of operating indefinitely.

New Renewable Energy Alternatives Geothermal Energy

Another reason why geothermal energy may not always be renewable is that patterns of geothermal activity in Earth’s crust shift naturally over time, so an area that produces hot groundwater now, may not always do so.


Geothermal Energy

Geothermal energy can be harnessed directly from geysers at the surface, but most often wells must be drilled down hundreds or thousands of meters toward heated groundwater.


Geothermal Energy

Generally, water at temperatures of 150-3700 or more is brought to the surface and converted to steam by lowering the pressure in specialized compartments.


Geothermal Energy

The steam is then used in turning turbines to generate electricity.


Geothermal Energy

Hot groundwater is used to heat, homes, buildings, greenhouses, etc.

The thermal energy from either water or solid earth can also be used to drive a heat pump to provide energy.


Geothermal Energy

Use of geothermal power is growing.

Though it provides less than 0.5% of the world’s total primary energy, it produces more power than solar and wind combined but a fraction of the power we get from hydropower and biomass.


Geothermal Energy

Geothermal energy in the U.S. provides enough power to supply electricity to over 1.4 million homes.


Geothermal Energy

At the world’s largest geothermal power plants, the Geysers in northern California, generating capacity has declined more than 50% since 1989 as steam pressure has declined.


Geothermal Energy

Japan, China and the U.S. lead the world in use of geothermal power.


Geothermal Power – Benefits

Geothermal power greatly reduces emissions relative to fossil fuels

Geothermal sources can release variable amounts of gases dissolved in their water (CO2, CH4, NH4, H2S)


Geothermal Power – Benefits

However, these gases are released in very small quantities.

By incorporating the latest filtering technologies, fewer emissions are produced.


Geothermal Power – Downsides

Geothermal sources are not always sustainable

the water of many hot springs is laced with salts and minerals that corrode equipment and pollute the air.


Geothermal Power – Downsides

These factors shorten the lifespan of plants, increase maintenance costs, and add to pollution.

Finally, geothermal energy is limited to areas where the energy can be tapped.


Ocean Energy

The potential is there to harness energy from the ocean’s waves, tides and temperature.


Ocean Energy – Wave power

Kinetic energy (movement) exists in the moving waves of the ocean. That energy can be used to power a turbine.





The wave rises into a chamber.

The rising water forces the air out of the chamber.

The moving air spins a turbine which can turn a generator. When the wave goes down, air flows through the turbine and back into the chamber through doors that are normally closed.





This is only one type of wave-energy system. Others actually use the up and down motion of the wave to power a piston that moves up and down inside a cylinder. That piston can also turn a generator.

Most wave-energy systems are very small. But, they can be used to power a warning buoy or a small light house.


Ocean Energy – Wave power technology


Ocean Energy - Wave power technologyBioWave - based on the swaying motion of

sea plants in the presence of ocean waves






Ocean Energy – Wave Power Technology


Ocean Energy – Wave Power Technology


Ocean Energy – Water temperature

Ocean Thermal Energy Conversion (OTEC) uses the temperature difference that exists between deep and shallow waters — within 20° of the equator in the tropics — to run a heat engine.

New Renewable Energy AlternativesOcean Energy – Water Temperature


Ocean Energy – Water Temperature

Because the oceans are continually heated by the sun and cover nearly 70% of the Earth's surface, this temperature difference contains a vast amount of solar energy which could potentially be tapped for human use.



The total energy available is one or two orders of magnitude higher than other ocean energy options such as wave power.

The small size of the temperature difference makes energy extraction difficult and expensive.

Hence, existing OTEC systems have an overall efficiency of only 1 to 3%.



So, the OTEC approaches are based on this gradient in temperature.

In the Closed Cycle approach, warm surface water is piped into a facility to evaporate chemicals, such as ammonia, that boil at low temperatures.



Closed Cycle Approach

These evaporated gases spin turbines to generate electricity. Cold water piped in from ocean depths then condenses the gases so they can be reused.





Open Cycle Approach

Here, the warm surface water is evaporated in a vacuum, and its steam turns the turbines and then is condensed by the cold water.


Ocean Energy – Water TemperatureOpen Cycle Approach

Because the water losses its salts as it evaporates, water can be recovered, condensed and sold as desalinized freshwater for drinking or agriculture.


Ocean Energy – Water TemperatureOpen Cycle Approach


Ocean Energy – Water TemperatureOpen Cycle Approach – Proposed Offshore


Hydrogen

All the renewable energy sources we have discussed can be used to generate electricity more cleanly than can fossil fuels.


Hydrogen

The one major problem that all of these technologies have is that the energy that they generate can not be stored for later use.


Hydrogen

The development of fuel cells and hydrogen fuel show promise to store energy conveniently and in considerable quantities and to produce electricity at least as cleanly and efficiently as renewable energy sources.


Hydrogen

In this system, electricity generated from wind or solar can be used to produce hydrogen and then be stored in fuel cells until it is needed.


Hydrogen

These hydrogen fuel cells can then provide electrical energy to; power vehicles, computers, cell phones, home heating, and other electrically based items.


Hydrogen

Fuel cell technology has existed since the 1960’s in NASA’s space flight program.


Hydrogen

Hydrogen fuel can be produced from water or from other matter.

How can this be done?


Hydrogen

Studies show that hydrogen atoms tend to bind to other molecules, becoming incorporated in everything from water to organic molecules.

Hydrogen must be ‘forced’ from the matter or state in which it resides.


Hydrogen

A process called, “electrolysis” involves electricity being used to ‘split’ hydrogen atoms from the oxygen atoms of water molecules.


Hydrogen

Electrolysis produces pure hydrogen and does so without emitting the carbon- or nitrogen-based pollutants of fossil fuel combustion.


Hydrogen

It is important, though, that the electricity generated and used in this process of “electrolysis” does not, in itself, produce pollutants.


Hydrogen – Sources

Hydrogen can be obtained from several sources: biomass, water and fossil fuels.

Using fossil fuel (CH4) as a source could create emissions of carbon.


Hydrogen – Fossil Fuel source

By using Methane (CH4), 4 hydrogens would be obtained for every carbon.This means that the ‘greenhouse gas’ carbon would be released in this process.


Hydrogen

Recent research suggests that if large amounts of hydrogen were purified some amount would eventually ‘leak-out’.

The concern is that this free hydrogen gas could deplete stratospheric ozone and lengthen the atmospheric lifetime of the greenhouse gas methane.


Hydrogen

This then is a concern on the part of some scientists that we first determine if this is a possibility before pursuing this new technology on an expanded scale.


Hydrogen

Therefore, once Hydrogen gas has been isolated, it can be used as a fuel to produce electricity within fuel cells.

The chemical reaction is just opposite that of electrolysis.


Hydrogen

An oxygen molecule and two hydrogen molecules each split, so that their atoms can bind to form two water molecules

2H2 + 02 --- 2H20


Hydrogen


Hydrogen

Hydrogen gas is allowed into one side of the cell, whose middle consists of two electrodes that sandwich a membrane that only protons can move across.


Hydrogen

One electrode strips the hydrogen gas of its electrons, creating two hydrogen ions that begin moving across the membrane.


Hydrogen

On the other side of the cell, oxygen molecules from the open air are split into their component atoms along the other electrode.

New Renewable Energy AlternativesHydrogen

These oxygen ions soon bind to pairs of hydrogen ions traveling across the membrane, forming molecules of water that are expelled as waste, along with heat.


While this is occurring, the electrons from the hydrogen atoms have traveled to a device that completes an electric current between the two electrodes.


Hydrogen

The movement of the Hydrogen’s electrons from one electrode to the other creates the output of electricity.

http://nano.mtu.edu/images/HydrogenFuelCell.gif



Hydrogen and Fuel cell benefits

Hydrogen is the most abundant element

It is clean and nontoxic to use

It produces the fewest greenhouse gases


Hydrogen and Fuel cell benefits

Fuel cells are silent, nonpolluting, and allow energy to be stored in the form of hydrogen.

Hydrogen and its use in fuel cells is energy-efficient


Algae – Hydrogen fuel source?Algae, found as pond scum could be a source of hydrogen for future fuel cells.


Algae – Hydrogen fuel source?

Melis, at UC Berekley, found that a particular algae emitted hydrogen when it is deprived of light.

He hypothesized that it could be encouraged to produce even more hydrogen.



Green algae, like green plants, photosynthesize.

The plant takes in C02 and water and light then converts these to food.



The by-product from this reaction is Oxygen.

This particular alga, however, has an enzyme that can stop producing Oxygen and start producing Hydrogen.



This enzyme, that allows the alga to produce Hydrogen, known as hydrogenase, only becomes active when the plant is deprived of light.



Melis’s group wanted to activate the hydrogenase and produce more hydrogen.

However, keeping the alga in the “dark” did not elevate hydrogen levels.



The reason was due to the fact that the alga’s metabolism was slowed during the period of little light.

So, the researchers limited the alga’s 02 output by putting it on a sulfur-free, bright-light regimen.



Not having sulfur hindered photosynthesis which then limited 02 output.

This activated hydrogenase and increased hydrogen production.



Since light was available, the alga was metabolically active and released a lot of its by-products.

They cultured large amounts of this alga and exposed them to these conditions that favored high levels of hydrogen output.



Their hypothesis was proven correct.

Without sulfur or photosynthesis, the algae did not produce Oxygen.

New Renewable Energy AlternativesAlgae – Hydrogen fuel source?

By not producing Oxygen (anaerobic), the alga began producing hydrogenase.

As a result, the plants began releasing amounts of hydrogen that were substantial relative to the size of the algal cultures.



As this type of research continues, it is possible that we may find, in the future, that photobiological methods will serve as a significant approach for generating the hydrogen that will be used as the fuel we put into our cars, planes, buses, etc.

New Renewable Energy AlternativesFuel Cell TechnologyTypes of Fuel Cells

1. Polymer Electrolyte Membrane (PEM) Fuel Cells

2. Direct Methanol Fuel Cells 3. Alkaline Fuel Cells 4. Phosphoric Acid Fuel Cells 5. Molten Carbonate Fuel Cells 6. Solid Oxide Fuel Cells

7. Regenerative Fuel Cells

New Renewable Energy AlternativesFuel Cell Technology

Fuel cells are classified by the electrolyte they use.

This determines the kind of chemical reactions that take place in the cell, the kind of catalysts required, the temperature range in which the cell operates, and the fuel required etc.


1. Polymer Electrolyte Membrane (PEM) Fuel Cellsaka: proton exchange membrane fuel cells

Advantages:- deliver high power density- low weight and volume- use a solid polymer as an electrolyte

and

porous carbon electrodes containing

a platinum catalyst

New Renewable Energy AlternativesFuel Cell Technology Polymer Electrolyte Membrane (PEM) Fuel Cells

Advantages:- need only hydrogen, ambient 02, and

H20 - don’t require corrosive fluids- fueled with pure hydrogen- operate at low temps (~ 80°C/176°F)

- - Low temps allow quick start which results in less wear & better

durability


Polymer Electrolyte Membrane (PEM) Fuel Cells

Disadvantages:- requires noble-metal catalyst (platinum)

to separate hydrogen's electrons & protons ($)

- platinum is extremely sensitive to CO poisoning (req something to reduce CO)

Note: exploring platinum/ruthenium catalysts-more resistant to CO.

New Renewable Energy AlternativesFuel Cell Technology Polymer Electrolyte Membrane (PEM) Fuel Cells


Polymer Electrolyte Membrane (PEM) Fuel Cells

Applications:- primarily for transportation, some

stationary applications

- suitable for passenger vehicles, i.e. cars

and buses


Significant barrier hydrogen storage

Most fuel cell vehicles (FCVs) powered by pure hydrogen must store the hydrogen onboard as a compressed gas in pressurized tanks.

The issue is using a low density fuel like hydrogen vs. high density fuel like methanol, ethanol, natural gas, liquefied petroleum gas, & gasoline (req. larger supply tank)

Hydrogen would deliver 300-400 miles

Onboard fuel processor needed to reform methanol et. al. to hydrogen.

This would increase costs / maintenance and reformer releases C02 (a greenhouse gas), but less than a gasoline-powered engine.

New Renewable Energy AlternativesFuel Cell TechnologyDirect Methanol Fuel Cells

DMFCs are powered by pure methanol, mixed with steam and fed directly to the fuel cell anode.

Advantages:

- DMFCs don’t have many of the fuel storage problems of some fuel cells (methanol has a higher energy density than hydrogen)

- Methanol is easier to transport / supply, uses current infrastructure, like gasoline

New Renewable Energy AlternativesFuel Cell TechnologyAlkaline Fuel Cells (AFCs)

first fuel cell technology developed

first type widely used by NASA to produce electrical energy and water onboard spacecraft

use a KOH (potassium hydroxide) solution as the electrolyte

can use a variety of non-precious metals as a catalyst at the anode and cathode

High-temp AFCs operate between 100°C - 250°C (212°F - 482°F)

newer AFCs operate between - 23°C to 70°C (74°F to 158°F)

New Renewable Energy AlternativesFuel Cell Technology AFCs

New Renewable Energy AlternativesFuel Cell Technology Alkaline Fuel Cells

Advantages: - high performance is due to the

rate of the chemical reaction that takes place

- 60% efficiency in space applications

New Renewable Energy AlternativesFuel Cell Technology Alkaline Fuel Cells

Disadvantages: - easily poisoned by CO2 therefore fuel must be

purified which is a costly process

- Duration of operation is ~8,000 hrs. must exceed 40,000 hrs to be economic

- material durability issue is the most significant obstacle in commercializing this fuel cell technology.

New Renewable Energy AlternativesFuel Cell Technology Phosphoric Acid Fuel Cells

- liquid phosphoric acid is the electrolyte (in a Teflon- bonded silicon carbide matrix

- contains a platinum catalyst


- “first generation" fuel cell- most mature cell types; over 200 units

in use

Applications: - stationary power generation

- used to power large vehicles, i.e. city

buses


Advantages:- more tolerant of impurities in fossil fuels; "poisoned"

by C02 that binds to platinum catalyst at the anode, decreasing fuel cell's efficiency.

- 85% efficient when used for the co-generation of electricity and heat

Disadvantages:- less powerful than other fuel cells, given the same

weight and volume therefore, these fuel cells are typically

large and heavy

- expensive, require platinum catalyst increases cost of the fuel cell ($4,000 - $4,500 /kilowatt) to operate

New Renewable Energy AlternativesFuel Cell Technology Molten Carbonate Fuel Cells

Applications:

- MCFCs currently being developed for natural gas and coal-based power plants for electrical utility, industrial, and military applications

- MCFCs are high-temp fuel cells, use electrolyte of molten carbonate salt mixture in a porous, chemically inert ceramic lithium aluminum oxide (LiAlO2) matrix

Advantages:- Since they operate at high temps (650°C / 1,200°F) non-precious metals

are used as catalysts at the anode and cathode, reducing costs


Advantages:- Improved efficiency & significant cost reductions

over phosphoric acid fuel cells (PAFCs)

- MCFCs approach 60% efficiency, > than 37-42% efficiencies of PAFC plant

- When waste heat is captured & used, overall fuel

efficiencies can reach 85%


Advantages:- MCFCs don't req external reformer to convert fuels to hydrogen

- at high temps, MCFCs can convert fuel to hydrogen within the fuel cell itself This is called, “internal reforming”it reduces costs

- Not prone to C02 or CO

poisoning


Advantages:- can even use carbon oxides as fuel (i.e. fuels w/gases made from coal). Could be capable of internal reforming of coal if

resistant to sulfur and particulates

Disadvantages:- MCFC durability - high temps cause electrolyte to corrode and breakdown, decreasing cell life

Note: exploring corrosion-resistant materials for components as well as fuel cell designs that increase cell life without decreasing performance

New Renewable Energy AlternativesFuel Cell Technology Solid Oxide Fuel Cells

- SOFCs use a hard, non-porous ceramic compound as the electrolyte. Since electrolyte is solid, the cells do not have to be constructed in the plate-like configuration like other fuel cell types

- 50-60% efficiency @ converting fuel to electricity

- with a design to capture & use system's waste heat

(co-generation) efficiency could top 80-85%

New Renewable Energy AlternativesFuel Cell Technology Solid Oxide Fuel Cells

Advantages:

- SOFCs operate at high temps (1,000°C/1,830°F)

- this removes the need for precious-metal catalyst (reduces cost) and allows SOFCs to reform fuels internally

- SOFCs are a sulfur-resistant fuel cell

- not poisoned by CO, therefore SOFCs can use

gases made from coal.

New Renewable Energy AlternativesFuel Cell Technology Regenerative Fuel Cells

- RFCs produce electricity from hydrogen and oxygen

- heat and water are byproducts (just like other fuel cells)

- RFCs use electricity from Sun or some other source to divide the excess water into oxygen & hydrogen fuel - "electrolysis"


Fuel Cell Technology Solid Oxide Fuel Cells


Fuel Cell Technology Solid Oxide Fuel Cells

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