Renewable Energy Sources Flashcards
What is biomass?
Any material derived from a living organism (Ex: wood, crops, animal waste)
What is biofuel?
- Processed biomass (Ex: ethanol, gasohol ethanol)
- Processed biomass that is renewable, but is limited by the rate of use and production
What is hydroelectricity?
Form of energy that harnesses the power when water is in motion
How is water harnessed to create energy?
- It utilizes the gravitational potential energy of water in reservoirs behind dams
- The water flows and is directed through pipes to the powerhouse, turning the turbines which turn the generator to create energy
- The higher the volume of water and further distance it falls, the greater amount of energy is produced
- The water doesn’t have to be in a dam to generate electricity. As long as water flows past the turbine, which turns the generator, it can create electricity
How does using hydroelectric power affect the environment?
- Hydroelectric power does not generate air pollution or waste, but the construction of power plants can be very expensive, and there may be a loss of or change in habitats following the construction of dams
- When people install dams, it can often disrupt the fish population, and change the habitat of aquatic environments
- There can be flooding of land for the reservoir
- Places to build hydropower are limited, using all limited land can cause a loss in habitats, biodiversity, and even agricultural land
- It could also change the water temperature and the river’s flow, thus affecting the aquatic organisms living there
What are the four generations of biofuels and their characteristics?
1st Generation:
- Grown on arable lands and are often food crops (ex: sugarcane or corn)
2nd Generation:
- Produced from crop byproducts; cellulose biomass not sugars or oils
3rd Generation:
- Based around algae with high lipid oil content; grown in bioreactors or wastewater ponds
4th Generation:
- Living material used to produce energy directly
Advantages of Hydroelectric Power
- High net energy gain
- High efficiency
- Reservoirs used for recreation and irrigation
- Provide flood control
- Long life spans
Disadvantages of Hydroelectric Power
- High construction costs
- River diversions during and often after construction
- High initial CO2 production from rotting material within the reservoir
- Dams interfere with fish migration
- Possible flooding of river valleys behind dams
How does the use of biomass affect the environment and human health?
- The burning of biomass produces heat for energy at a relatively low cost, but it also produces carbon dioxide, carbon monoxide, nitrogen oxides, particulates, and volatile organic compounds (which can cause breathing issues in humans)
- The overharvesting of trees for fuel also causes deforestation
- Using wood as a source of heat can become dangerous; If not properly disposed of, it can lead to forest fires, which damages existing resources
- Overcropping causes soil erosion because depleted soil cannot sustain vegetation and holds less soil moisture
Describe methods of conserving energy
- Unplug electronics when they are not in use
- Turn off lights when you leave a room
- Use energy-efficient appliances
- Use natural light instead of electricity when possible
- Wash your clothes in cold water and air dry
- Avoid your oven and use the microwave instead
- Take short and cold showers
- Utilize natural ventilation
Where are water sources found globally?
- Rivers, oceans, lakes, etc.
Where are resources for biomass-produced energy found?
- Crops (where agriculture takes place)
- Forests (South America)
- Small plants and grasses
What is wind energy?
Wind turbines use kinetic energy to convert wind into electricity
What is solar energy?
- Solar panels convert sunlight into electricity
How are photovoltaic solar panels and concentrated solar panels different?
- Photovoltaic solar panels have 2 layers of silicon: the sun strikes the silicon, excites electrons, and creates energy
- Concentrated solar panels have mirrors: the sun strikes the mirrors, it creates heat and steam which then enters a turbine that creates electricity
How does wind energy work?
- Much like other forms of energy production, wind creates energy by turning a turbine that’s part of a generator
- Unlike fossil fuels, however, wind turbines use the kinetic energy of the wind to rotate the turbine.
What are wind farms? Where are they usually located? What is the benefit of wind farms?
- Wind Farms: large areas where wind turbines are grouped together
- Used to better harvest wind energy, placed in areas with high wind activity, typically mountains or close offshore
- Land can still be used for other purposes, like agriculture, bc wind turbines have minimal impact on land
What are the pros of wind energy?
- Renewable
- A fastest growing renewable resource
- A wind farm can be built in a few years which is very fast compared to other energy sources
- Affordable
- No greenhouse gas emissions once it’s built
What are the cons of wind energy?
- Wind is intermittent, meaning that it only makes power when the wind is blowing
- Wind turbines kills birds and bats
- Building of wind turbines requires mining for metals which causes erosion, contamination of groundwater, and pollution
- Many people don’t want to live near wind turbines, but if you place them offshore away from people, then it becomes a lot more expensive
How do solar panels harness energy from the sun to convert into electricity?
- Solar panels are comprised of one positively charged layer of silicon and one negatively charged layer of silicon
- When the sun strikes the solar panels, the electrons between the layers are excited
- The electric field produced by the solar panels force the electrons to flow towards the conductive metal plates that line the panel
- This is called an energy current and the electricity that the panel can produce is determined by how strong this current is
- The current is then directed into wires, which allows for usable forms of electricity.
What are the pros of solar energy?
- Environmentally friendly: no greenhouse gas emissions
- Cheap
- Low-maintenance
- Easily installed because panels are small and lightweight
- Market is growing rapidly – lots of jobs
What are the cons of solar energy?
- There is a high upfront cost of solar panels
- Initial production will result in pollution
- The intensity of the sun varies throughout the year and no energy is produced at night
- Solar farms need very large areas of land in order to operate which displaces wildlife
- Some resources that are needed to make solar panels are scarce
- Chemicals and metals, which are hazardous waste products, are disposed into landfills after they stop working
What is geothermal energy?
- Heat from the earth’s core harnessed into energy
- Heat is far down in the earth’s crust and can be expensive or not a viable energy source when heat is not easily accessible
Where and how are geothermal reservoirs found in the earth? Where are the most active geothermal reservoirs?
- Geothermal reservoirs are deep underground and difficult to detect
- In order to locate them, you must drill a well and test the temperature
- The most active geothermal reservoirs can be found near large tectonic plate boundaries
- However, geothermal energy within the Earth can be tapped into almost anywhere, from a few feet to a few miles underground
What country is the largest producer of geothermal energy? Where is most geothermal energy found in the United States?
- In the US, most geothermal energy resources are found in the West and Hawaii, where geothermal resources are closer to the surface and easier and cheaper to access
- There are 7 states with geothermal power plants: California, Nevada, Utah, Hawaii, Oregon, Idaho, and New Mexico
- It accounts for 0.4% of total U.S. energy production for a total of 17 billion kWh in 2020
How is heat harnessed to produce electricity?
- Water is pumped down an injection well
- Heat in Earth’s interior turns that water into steam
- Steam rises in the production well
- Kinetic energy of steam turns a turbine
- Turbine turns a generator - produces electricity
How can geothermal energy help with heating/cooling houses? What are its benefits and disadvantages compared to traditional AC/Heating systems?
- Can move energy between a house and the ground to heat/cool down home
- Pipes filled with water circulate between the home and the ground; the air is blown over pipes and the air turns to the temperature of the pipes
- more expensive than traditional AC/Heating systems to install (around 200ft. )
Benefits: cheaper to maintain, long-lasting, sustainable
Benefits of Geothermal Energy
- Constant electricity production - regardless of weather
- Small Environmental Footprint (uses less land per Gigawatt Hour than coal, wind, or solar)
- Emits no greenhouse gasses
- Uses less water than other sources of electricity (natural gas, coal)
- 4x less greenhouse gas emissions than solar as a whole
- Renewable - heat within the earth is constantly being produced
- Multiple uses (heating, electricity, cooling)
Cons of Geothermal Energy
- Economic viability of geothermal is not always available
- High Cost vs. Low Energy
- Hydrogen sulfide gas is released during drilling and processing
- Possible short-term depletion of heat
- Can impact groundwater
How do hydrogen fuel cells generate electricity?
They use hydrogen as fuel, combining the hydrogen & oxygen in the air to form water & release energy (electricity) in the process.
What are the emissions from hydrogen fuel cells?
Water
What is the difference between a hydrogen fuel cell and a typical battery?
- In a typical battery, the chemicals are in a closed container.
- Once used, the battery must be charged or discarded.
- in a hydrogen fuel cell, the chemical reactants can be added continuously
- The fuel cell does not “go dead”
What is the first step of the hydrogen fuel electricity generation process? What happens in the two separate layers of reaction for a hydrogen fuel cell?
First Step: Hydrogen fuel (H2) is added to the cell
- This can be in liquid or gas form
- In the 1st reaction layer, hydrogen molecules are split into protons (H+) & electrons (-)
- Protons & electrons take different paths.
- Protons move across the membrane
- Electrons are free to take an alternate route, creating a flow of electric current
- In the 2nd reaction layer, Oxygen molecules (O2) are split & combine with protons & electrons
What are the inputs and products of hydrogen fuel cells in vehicles?
- Hydrogen gas is pumped in from a fuel pump
- Oxygen is taken in from the air
- Product is water vapor and heat
Where does hydrogen gas come from? How is it extracted from these substances? What are potential environmental consequences?
Usually found in compounds like water or natural gas
- Can come from water (H2O):
- Electrolysis - electric current used to split water into hydrogen & oxygen
- Can come from natural gas:
- Splitting methane (CH4) using heat (in the form of steam), results in CO2 pollution
What factors of hydrogen fuel cells’ electricity generation process decrease its net energy?
- Since we must create the hydrogen gas (isn’t found naturally) and it takes electricity or heat to break apart water or methane, this decreases the net energy of hydrogen as a fuel source
Net Energy
It is the amount of energy produced by the source minus energy used, lost, or wasted in the process of generating the useful energy
Benefits of Hydrogen Fuel Cells
- No CO2 emissions (if produced from water)
- Electricity is more efficient than internal combustion (seen as the future of transportation & energy needs)
- Could be sustainable if the energy used to produce hydrogen is produced using sustainable sources (ie solar PV)
- Range of the fuel tank is about the same as a conventional car
Negative Consequences of Hydrogen Fuel Cells
- Technology is expensive
- Producing hydrogen fuel from fossil fuels is not clean
- Currently producing hydrogen fuel requires a relatively high amount of energy
- At the moment most of the hydrogen for fuel cells is produced by steam reforming from natural gas and the rest is produced by electrolysis.
- Operation is limited by the amount of available fuel: lack of infrastructure
