martes, 14 de abril de 2015

miércoles, 25 de febrero de 2015

jueves, 19 de febrero de 2015


Complete the following test


miércoles, 11 de febrero de 2015

Nuclear energy

Nuclear energy

Electricity production in a nuclear power plant


Main components of a nuclear reactor

Core – It’s the focal point of the reactor, where fuel is contained and nuclear fission reactions take place.
Fuel – Generally, fuel is made of small enriched uranium oxide rods, stacked so as to form cylinders. These rods are wrapped in metal sheathes (steel or zirconium alloy), which allow heat to pass through while blocking the radioactive elements produced by fission.
Moderator – This is a material placed in the reactor to slow down the neutrons produced by fission, in order to reach the most suitable speed allowing the chain reaction to continue.
Heat-transfer fluid (or coolant) - This fluid (liquid or gas) cools the core and carries outside the heat that is produced there. The most commonly used fluid is water.
Control rods – These are rods used in specific materials (silver, indium, cadmium or boron carbide) to control fission inside the core. 
Vessel – The large steel recipient containing the core, the control rods and the heat-transfer fluid.
All the components of the reactor are container in a solid concrete structure that guarantees further isolation from external environment. This structure is made of concrete that is one-metre thick, covered by steel. The most recent reactors sometimes contain two containment structures and are designed to defy all types of accidental events, even the impact of an aircraft.


martes, 10 de febrero de 2015



There are four main parts to a wind turbine:
- The base
- The tower
- The nacelle
- The blades

The blades

The blades spin at a low rate of about 20-30 rpm. They are made of fiberglass-reinforced polyester.

The nacelle

The nacelle houses a generator and gearbox. As the gearbox spin, the electricity is produced.

The tower

The most common tower design is a white steel cylinder, about 25-100m  tall and 30mt in diameter.  Contains the electrical conduits, supports the nacelle and provides access to the nacelle to maintenance (ladder and lift). It´s made of grey steel.

The base

Bases are made of concrete reinforced with steel bars, supports the whole structure.

lunes, 9 de febrero de 2015





A solar panel is a device that collects photons or sunlight, which are very small packets of electromagnetic radiation energy, and converts that into heat.


These plants use the energy from the sun. There are two main types of installations: photo-thermal and photovoltaic power plants.

Photo-thermal power plant

In this type of power plant, the heat generated by solar radiation produces steam that is used to move the rotor in the generator.

To do this, they use special mirrors, called heliostats,  that reflect sunlight and concentrate it at one point, where it reaches a high temperature.

Photovoltaic power plant

In these power plants, solar radiation is transformed directly into electricity by panels of photovoltaic cells.
These power plants consist of large areas of photovoltaic panels.

domingo, 8 de febrero de 2015


We as humans create a huge amount of byproducts including human waste, general waste, animal waste, and much more. Biomass energy technologies now takes advantage of these by burning byproducts to create electricity instead of further polluting the atmosphere.
Many waste treatment facilities and landfill sites are moving to biomass energy to create power and to make their towns and cities cleaner.

Process to obtain energy from biomass and waste

The most used method today is combustion, where all the carbon in the fuel is totally transformed into carbon dioxid and where the only product is heat. The heat from the combustion process can be used directly or for power production.  Gasification is a process where the fuel is partially oxidised and the product is a fuel gas consisting of CO, CO2, H2, CH4, H2O and N2. This fuel gas can be utilized in an engine, gas turbine or boiler for heat and power production. A third option for thermochemical conversion of biomass or waste is pyrolysis. Pyrolysis means to heat up the fuel in the absence of oxygen. The product from this process is charcoal, pyrolysis oil and a fuel gas. The charcoal can be used for barbeque or in the metallurgical industry. The pyrolysis oil can be utilized as a fuel for vehicles or for power production via engine or gas turbines. The combustible fuel gas can be utilized in an engine, gas turbine or in a boiler for power and heat production. Pyrolysis gives in other words more flexibility both in terms of storage and transportation and usage of the products compared to ordinary combustion. The figure below shows an overview of the different process and utilization of products.