Brought to You By: Alvaro PenaLondon PresentationNovember 16, 2011

Renewable Energy

New and emerging renewable energy technologies are still under development. These technologies are not yet widely demonstrated or have limited commercial reach. Many are on the horizon and may have potential comparable to other renewable energy technologies, but still depend on attracting sufficient attention and research, development and demonstration (RD&D) funding.

New and Emerging Renewable Energy

Technologies

Is a form of hydropower that converts the energy of tides into useful forms of power - mainly electricity.

Tides are more predictable than wind energy and solar power. Among sources of renewable energy, tidal power has traditionally suffered from relatively high cost and limited availability of sites with sufficiently high tidal ranges or flow velocities, thus constricting its total availability.

TIDAL ENERGY

Many recent technological developments and improvements, both in design (e.g. dynamic tidal power, tidal lagoons) and turbine technology (e.g. new axial turbines, cross flow turbines), indicate that the total availability of tidal power may be much higher than previously assumed, and that economic and environmental costs may be brought down to competitive levels.

A huge dam (called a "barrage") is built across a river estuary. When the tide goes in and out, the water flows through tunnels in the dam. The ebb and flow of the tides can be used to turn a turbine, or to push air through a pipe, which then turns a turbine

The "Swanturbines" is a direct drive design , where the blades are connected directly to the electrical generator without a gearbox between. It also uses a "gravity base", a large concrete block to hold it to the seabed, rather than drilling into the seabed.

Once you've built it, tidal power is free.It produces no greenhouse gases or other

waste. It needs no fuel. It produces electricity reliably. Not expensive to maintain. Tides are totally predictable. Offshore turbines and vertical-axis turbines

are not ruinously expensive to build and do not have a large environmental impact.

ADVANTAGES

A barrage across an estuary is very expensive to build, and affects a very wide area - the environment is changed for many miles upstream and downstream. Many birds rely on the tide uncovering the mud flats so that they can feed. Fish can't migrate, unless "fish ladders" are installed.

Only provides power for around 10 hours each day, when the tide is actually moving in or out.

There are few suitable sites for tidal barrages

DISADVANTAGES

Enhanced Geothermal System EGS technologies enhance and create

geothermal resources in this hot dry rock through hydraulic stimulation. When natural cracks and pores do not allow economic flow rates, the permeability can be enhanced by pumping high-pressure cold water down an injection well into the rock. The injection increases the fluid pressure in the naturally fractured rock, mobilizing shear events that enhance the system's permeability.

Permeability may be enhanced by inducing slippage along preexisting fractures or by hydraulic fracturing, using high-rate water injections, or chemical stimulation. Pressure depends on fracture patterns, stress magnitudes orientations and rock strength. Once the permeability has been increased, production can be sustained by injecting water into injection wells, where it is heated as it travels to the production wells. As the circulating water cools, the engineered fractures, induced seismicity, and chemical dissolution of minerals may also create new permeability.

In conventional geothermal-electricity generation, wells are drilled deep into fractured, high-temperature rock. Naturally occurring hot, pressurized water and steam are allowed to flow through the wells to the surface to turn steam turbines and produce electricity. Naturally occurring geothermal reservoirs are, however, limited in size, extent and duration

Differences

Stage 1--Selecting a candidate reservoir. A hot, tectonically stressed region in the subsurface is identified and targeted for 'stimulation

Stage 2--Stimulation of the incipient reservoir. Wells are drilled and water is injected under high pressure.

Stage 3--Production. Water is circulated through the newly created reservoir, extracting heat from the rock for use in producing geothermal electric power.

Steps

Disadvantages

Induced seismicityLife or Property Damage

Artificial Photosynthesis Is a chemical process that replicates the

natural process of photosynthesis. The term is commonly used to refer to any scheme for capturing the energy from sunlight and storing it in the chemical bonds of a fuel. Splitting water, or photo electrolysis, is one form of artificial photosynthesis that converts water into hydrogen and oxygen using sunlight.

The photosynthetic reaction can be divided into two half-reactions (oxidation and reduction), each of which is essential in producing fuel. In plant photosynthesis, water molecules are photo-oxidized to release oxygen and protons. The second stage of plant photosynthesis (also known as the Calvin-Benson cycle) is a light-independent reaction which converts carbon dioxide into glucose.

The Photovoltaic cells created splits water molecules to generate hydrogen gas. The cells are so powerful & efficient that they are capable of converting sunlight into chemical energy 10 to 40 times more times more efficiently than most crops. The biggest challenge that lies ahead will be the formation of hydrocarbons by combining hydrogen with carbon dioxide similar to the structure of diesel or aviation turbine fuel. Currently no established commercial processes exist for doing that.

Advantages The solar energy can be immediately

converted and stored. The byproducts of these reactions are

environmentally friendly. Artificially photosynthesized fuel would be a

carbon-neutral source of energy, which can be used for transportation or homes.

In reactions that consume carbon dioxide, the CO2 emissions from fossil fuels will be mitigated.

DisadvantagesMaterials used for artificial photosynthesis often corrode in water, so they are less stable than photovoltaic's over long periods of time.

The overall cost is not yet advantageous enough to compete with fossil fuels as a commercially viable source of energy.