Secondary Fuels

• electricity • hydrogen

a fuel that has been derived from primary fuels, by being converted into another energy form by physical or mechanical methods

transformation of one type of energy to another e.g. renewable to elec showing how electricity is generated

• kinetic • photovoltaic • chemical

• movement energy converted using a spinning electrical conductor in a magnetic field known as a generator • kinetic energy can be harvested directly - this could include in-stream HEP turbines and wind turbines, or may be produced by converting other types of available energy using fossil fuels or using any other form of heat (radiation etc) to heat pressurised water into steam and then passing it through a turbine to spin the generators

• photons of light strike the surface of photovoltaic cells displacing electrons • this leads to the surface being negatively charged • the free electrons can flow along a conductor to the lower layer (which is relatively positively charged) and this movement can be used to power electrical appliances

an electrochemical energy conversion device, converting the chemicals hydrogen and oxygen into water, and in the process it produces electricity - they use electrochemical cells to store energy in chemicals such as hydrogen and alcohols. Do not lose ability to produce electricity as long as a fresh supply of fuel is available for the hydrocarbon reaction

a battery has all of its chemicals stored inside, and it converts those chemicals into electricity too. This means that a battery eventually goes dead and you either throw it away or recharge it a fuel cell has chemicals constantly flowing into it so it never goes dead - so as long as there is a flow of chemicals into the cell, the electricity flows out of the cell

hydrocarbons alcohols hydrogen oxygen

• gas turbines in power plants • gasoline engine in cars • batteries (e.g. in laptops)

COMBUSTION ENGINES: (e.g. turbines, gasoline engines) burn fuels and use the pressure created by the expansion of the gases to do mechanical work BATTERIES: convert chemical energy back into electrical energy when needed FUEL CELLS = better because they should do both tasks more efficiently

• several different types of fuel cell, each using a different chemistry • fuel cells are usually classified by their operating temperature and the type of electrolyte they use • some types of fuel cells work well for use in stationary power generation plants. Others may be useful for small portable applications or for powering cars

• generate elec quietly and efficiently • no pollution • only by-products are heat and water

• COST - currently high • LOW DURABILITY - difficult to contain effectively and safely • HYDRATION ISSUES - (how they work in hot/cold temps) • LACK OF INFR and storage, not widespread. Mainly London: some of the bus fleet is hydrogen • DANGEROUS - hydrogen is very combustible and dangerous

• no pollution is caused when it is used • converting electricity to other energy forms (e.g. sound, light, heat, mvmt) is straightforward • transportation is easy via conducting cables

• converting primary fuel to electricity is not very efficient • storing electricity is difficult as there are no large-scale options currently • the initial production of electricity may be highly polluting

• nuclear reactor • control rods • boiler • steam turbines • generator • condenser

a) the heat generated by nuclear fission is used to heat the primary coolant (pressurised water) b) control rods absorb neutrons. They are lowered into the reactor or raised out of it to control the power output c) the hot primary coolant heats water which boils to produce high pressure steam

a) the kinetic energy of the high pressure steam is absorbed and spins the turbines b) the rotating turbines turn the generator which produces electricity c) the steam which has cooled and lost its pressure is condensed using cold water from a river, lake or the sea

• chemical energy can be converted to electricity in reactions where one chemical accepts electrons at an electrode and another chemical releases electrons at another electrode • the electrons flowing between the electrodes can be used to power electrical equipment

• electrochemical cells • rechargeable batteries • fuel cells

• in batteries to store chemical energy that can be converted to electricity • when the chemical reactions take place, the battery loses its ability to produce more electricity

use electricity to reform the chemicals that produce electricity

uses hydrogen and oxygen as fuel - hydrogen releases electrons while oxygen accepts them - the resulting hydrogen and oxygen ions combine to create water