Hydrogen Fuel Cells Overview

Hydrogen Fuel Cells

• Hydrogen fuel cells are an alternative to non-renewable fuels.
• Similar to batteries, but fuel cells have an open container, allowing continuous reactant additions, preventing them from "dying".
• Hydrogen fuel cells use hydrogen (liquid or gas) as fuel.
• Hydrogen molecules split into protons (H+) and electrons (-).
• Protons and electrons take separate paths, with protons passing through a membrane, and electrons generating an electric current.
• Oxygen molecules split; protons and electrons recombine with oxygen to produce water vapor.
• Fuel cell vehicles (FCVs) are a use case for this technology.
• FCVs connect to hydrogen tanks, which is suitable for buses that are not suitable for electric vehicles.

Pros of Hydrogen Fuel Cells

• Produce no CO2; only water vapor is emitted.

Cons of Hydrogen Fuel Cells

• Hydrogen gas is explosive and rare in nature.
• Hydrogen can be produced by electrolysis (water split by electricity) or from natural gas (methane splitting, leading to CO2 emissions).
• Producing hydrogen requires energy, decreasing net energy output.
• No energy conversion is 100% efficient; losses are inevitable.
• Hydrogen production from fossil fuels isn't clean.
• Technology is new and expensive.
• Low production scale leads to high current costs, but decreased costs are anticipated with larger-scale manufacturing.

Wind Energy

• Wind turbines convert the kinetic energy of moving air into electricity.
• A renewable and clean energy source.
• Concerns about bird deaths caused by wind turbines.
• Wind power has increased in use since 2000, surpassing other energy sources.

Pros of Wind Energy

• Renewable and clean; no emissions.
• Allows for multiple land uses.
• Can be implemented in oceans.

Cons of Wind Energy

• Wind turbines kill birds.
  • Solutions include relocating turbines, studying migration patterns, and painting turbines dark to make them more visible to birds.
• Maintenance is required.
• Needs consistent wind with minimal blockage for reliable power supply.
• Requires backup power on windless days.

Energy Conservation Methods

• Adjusting thermostats for reduced heating and cooling.
• Conserving water (shorter showers, etc.).
• Using energy-efficient appliances (e.g., light bulbs).
• Implementing conservation landscaping (shading trees, windbreaks).
• Selecting plants that match the local climate to reduce water usage.
• Improving vehicle fuel economy (Corporate Average Fuel Economy standards regulate fuel efficiency).
• Using battery electric vehicles (BEVs) or fuel cell cars.
• Utilizing public transport.
• Implementing green building designs.
• Utilizing passive solar systems.
• Insulating homes to reduce heat loss.

Introduction to Air Pollutants

• Air pollutants are categorized as primary or secondary.
• Combustion of plant matter (oil, natural gas, coal) releases primary pollutants.
• Primary pollutants interact in the atmosphere to form secondary pollutants.

Primary Pollutants

• Natural: Pollen, volcanic ash, volatile organic compounds (VOCs) from plants.
• Anthropogenic: Pollution from fossil fuel combustion (CO2, NO, SO2).

Secondary Pollutants

• Form in the atmosphere through reactions with water vapor, other gases, or UV light.
• Examples include ozone and acid rain.

Clean Air Act

• Established in 1963
• 6 major pollutants deemed harmful to human health (identified by the EPA in 1970): Sulphur dioxide (SO2), Ozone (O3), Particulate matter (PM), Nitrogen dioxide (NO2), Lead (Pb), Carbon monoxide (CO)

Lead

• Historically used as a gasoline additive (1920s).
• Today, lead is removed from gasoline.
• Health consequences: Anemia, behavioral disorders, lowered IQ, learning disabilities, nerve damage (children); hypertension, cardiovascular disease (adults).
• Lead levels have decreased since the Clean Air Act.

Coal Combustion

• Coal formed from peat (organic matter).
• Releases CO2, SO2, and toxic heavy metals (lead, mercury, nickel, arsenic).
• Creates particulate matter, which carries metals into lungs.
• Coal often contains impurities that are released upon combustion.
• Coal processing involves decreasing impurities through heat and pressure: plant matter, peat, lignite, bituminous, anthracite

Sulfur in Fossil Fuels

• Coal has more sulfur than other fossil fuels, due to its rock cycle origin.
• Marine organisms contain sulfur and produce SO2 when burned.
• Sulfur emission reduction methods for coal include filters, wet and dry scrubbers, and clean coal processing.

Fossil Fuels

• Fossil fuels contain carbon (C) and hydrogen (H).
• Combustion of carbon produces CO2.
• Fossil fuel combustion releases energy from stored glucose (C6H12O6).

Effects of Pollution

• Air pollutants irritate eyes, nose, and throat.
• Inhaled pollutants affect lung conditions (e.g., asthma).
• Damage to plant tissues (photosynthesis and cellular respiration).

Photochemical Smog

• Primary pollutants (N oxides, VOCs) react with sunlight to produce secondary pollutants (ozone, PANs, nitric acid).
• Tropospheric ozone is a key component.
• VOCs also contribute.
• Nitric acid creates acid rain.

Volatile Organic Hydrocarbons (VOCs)

• Vaporize at room temperature.
• Examples: gasoline, formaldehyde (anthropogenic), trees, plant oils (natural), nail polish, essential oils.

Sources of Photochemical Smog

• Urban areas with many motor vehicles.
• VOCs primarily from gasoline.

Photochemical Smog Factors

• NO production peaks in the early morning.
• Ozone levels peak in the afternoon (highest sunlight and temperature).
• Higher in the south and during summer.

Photochemical Smog Effects

• Irritates eyes, nose, and throat.
• Aggravates existing heart and lung conditions.
• Long-term exposure can cause lung cancer.

Tropospheric Ozone Effects

• Worsens bronchitis.
• Causes asthma.
• Damages lung tissue.
• Damages plant tissues by entering through stomata.

Reducing Photochemical Smog

• Reduce Nitrogen Oxides: Catalytic converters in motors, emission standards for vehicles.
• Reduce VOCs: Avoid gasoline spills, nighttime refueling, follow vapor recovery guidelines.
• Other methods: public transportation, limiting outdoor activities in late afternoons (summer).

Thermal Inversions

• Normal air temperature decreases with altitude.
• An inversion is a warm layer between two cooler layers, trapping cooler air and pollutants near the ground.
• Problems in valleys, behind mountains, and along coastlines where sea breezes/ocean winds are not enough to lift the trapped pollutants.
• Worsens pollution in industrialized cities with traffic.

Pollution Sources

• Land, stationary factories, mobile vehicles, natural sources.

Natural CO2 Emissions

• Respiration, ocean outgassing, decomposition of biomass, volcanic eruptions, wildfires.
• Natural sources have a limited net effect compared to anthropogenic CO2 emissions.

Particulate Matter (PM)

• Solid or liquid particles small enough to inhale (1 micron = .001mm).
• PM10 (2.5-10 microns) trapped in upper respiratory system; PM2.5 (<2.5 microns) trapped in the lower respiratory system.

Natural PM Sources

• Pollen, spores, bacteria, dust, soil, sea salt, volcanic dust, sulfates, wildfire ash.

PM Effects

• Intensifies asthma, coughing, eye and lung irritation, skin rashes.

Explore the science behind hydrogen fuel cells, an innovative alternative to traditional fuels. Learn how they function, their applications in vehicles, and the benefits and drawbacks associated with their use. Understand the processes involved, such as splitting hydrogen and the environmental impact of fuel cell technology.