Alternatives to fossil guels Flashcards
What are the main sources of renewable energy today?
Hydro, wind, solar (mainly via photovoltaic cells), geothermal and tidal.
What are photovoltaic cells?
Photovoltaic cells are now the most widely used method for generating electric power using solar cells to convert energy from the sun into an electric current that can be used to power equipment or recharge batteries.
What are the geographical reasons for renewable energy not working in every country?
Not all countries have coasts, strongly flowing rivers or climates with either long sunshine hours or persistently strong winds.
Apart from geographical reasons for renewable energy not working in every country, what are the other reasons?
The relative financial costs of using non-renewable and renewable energy sources. When oil and gas prices are low, renewable become a more expensive option.
The harnessing of renewable is not without environmental costs. Think of the drowning of river valleys to create HEP reservoirs, or the large areas of land and the offshore zone that will be covered by the required number of solar and wind farms.
While the majority of people believe that we should make greater use of renewable sources, most suddenly go off the idea when it is proposed to construct a wind or solar farm close to where they live.
What are the downsides to using nuclear energy?
Risks to do with safety (accidents) and security (terrorism).
The disposal of radio-active waste with an incredibly long decay life.
The technology involved is complex and therefore its use is only an option for developed countries.
Although the operational costs are low, the costs of constructing and decommissioning power stations are high.
What is biomass?
Biomass is organic matter used as a fuel, as for example in power stations for the generation of electricity.
What are the most widely grown biofuel crops?
Wheat, corn, grasses, soy beans and sugar cane.
What is the downside to biofuel crops?
Each hectare of farmland used to grow energy crops means a hectare less for growing much-needed food.
There is still some uncertainty over how carbon-neutral biofuel crops really are.
How many passanger vehicles sold in Brazil have flex-fuel engines that work using any combination of petrol and ethanol?
90%
What is biofuel?
Biofuel is derived directly from organic matter, such as agricultural crops, forestry or fishery products, and various forms of commercial and domestic waste.
What are primary biofuels?
Primary biofuels include fuelwood, wood chips and pellets, as well as other organic matter, that are used in unprocessed form, primarily for heating, cooking and electricity generation.
What are secondary biofuels?
Secondary biofuels are derived from the processing of biomass and include liquid biofuels, such as ethanol and biodiesel, which can be used in motor vehicles and some industrial processes.
What is carbon capture and storage?
Carbon capture and storage involves ‘capturing’ the carbon dioxide released by the burning of fossil fuel, and burying it deep underground.
Unfortunatly, it is an expensive process because of the complex technology involved. There is also some uncertainty whether the stored carbon will stay trapped underground and that it will not slowly leak to the surface and into the atmosphere.
Since it is widely accepted that fossil fuels will continue to provide most of the world’s primary energy, development of the carbon capture and storage technology must be given a high priority, as must also the slightly different technology that ‘scrubs’ some of the carbon dioxide out of exhausts produced by the burning of fossil fuels.
What are hydrogen fuel cells?
Hydrogen fuel cells combine hydrogen and oxygen to produce electricity, heat and water. They will produce electricity as long as hydrogen is supplied; they will never use their charge.
They are a promising technology for use as a source of heat and electricity for buildings, and as a power source for electric vehicles.
The challenge with this technology is finding a cheap and easy source of hydrogen. Although it is a simple and abundant chemical element, it does not occur naturally as a gas. It is always combined with other elements, for example with oxygen in water. Once this challenge has been met, these cells offer the real prospect of reducing carbon emissions.
