Where are greenhouse gases coming from?

The main greenhouse gas in our atmosphere is carbon dioxide (CO₂).  Carbon dioxide resulting from the combustion of petroleum, coal, and natural gas makes up 56.6% of all global anthropogenic greenhouse gas emissions.  17.3% of all global anthropogenic greenhouse gas emissions come from CO₂ as a result of deforestation, decay of biomass, etc.  Another 2.8% is also from CO₂ resulting from “other” activities such as cement production and natural gas flaring.

The next main greenhouse gas that is emitted is methane (CH₄).  Methane makes up roughly 14.3% of global anthropogenic greenhouse gas emissions.  Methane is produced from agriculture, oil and natural gas operations, coal mines and landfills.

Another main greenhouse gas produced by humans is nitrous oxide (N₂O), which makes up 7.9% of emissions.  Nitrous oxide comes from burning fossil fuels, the use of nitrogen fertilizers and certain industrial and waste management processes.

The last 1.1% of global emissions comes from several different fluorocarbons that are released as a result of various industrial processes.  Figure 1 below illustrates the above information in the form of a chart.

 Figure 1. Global Anthropogenic Greenhouse Gas Emissions in 2004

  

The next figure presents data on the major global sources of carbon dioxide (CO₂) emissions by country, from the beginning of the Industrial Revolution to the present. 

Figure 2. Global CO₂ Emissions from 1752-2006

Figure 3 is a graph that presents the global carbon emissions by fuel type from 1800-2007 in million metric tons of carbon, as reported by the Carbon Dioxide Information Analysis Center.

Figure 3. Global fossil carbon emission by fuel type

Two primary aspects of energy sustainability:

Can the current energy consumption profile last?
The state of the current energy profile is heavily dependent on the fossil fuels. In the economic sense the as the fuel begins into higher demand and the production begins to drop the price will increase. As discussed in class the current trend of use of fossil fuel can continue for only 100 more years, this will cause a steep increase in cost for the worlds energy cost. The current profile is on a sharp increase over the last hundred years. This trend cannot continue for the factor of cost and depletion in time.

If the current energy profile of the world is sustained what impact will it have on the environment?
One can only speculate the possibilities of the environment of the future, although examining our recent history hypothesis can be taken. The environmental impact of the current energy profile is a very noticeable amount in the last hundred year and noticeable effects have taken place in the environment. Increases in greenhouse gases and pollution have been exponentially experienced. The temperature, on average, of the world has increased. Though the increase of the temperature has only changed slightly the continuing trend could dramatically change the world's climate enough to effect living conditions.

What is the carrying capacity of the earth?

The carrying of humans in the earth's environment is defined as the largest population the earth can support and maintain indefinitely. Several factors for this include the amount of food to be produced, the space in which our population occupies, and vital necessities such as available water and resources in the environment.
In ideal equilibrium the capacity of the earth could hold near 15 billion people. However, the current lifestyle of living requires more energy and a larger impact altogether. The impact factor has been researched by Paul Ehrlich and he has developed a theory to calculate how a population can impact living using the IPAT. IPAT is an equation in which I=PAT, I stands for impact, P is population, A is affluence, and T is a technology factor. This impact is negative to the carrying capacity, to have everyone living on a decent standard of living with today's technology the earth is currently over populated with around 7 billion people. When the current suspected carrying capacity is thought of to be around 5 billion humans.

Slide #7: What are greenhouse gases? Sources? GWP?

  Greenhouse gases (GHG) are gases that have the ability to trap infrared radiation and act like a blanket to the Earth.  The increased emissions of these gases is what is contributing to global warming.
  The main GHG, in terms of human emissions, are the following (http://action.ran.org/index.php)

Carbon Dioxide, CO2
Methane, CH4
Nitrous Oxide, NO2
Sulfur Hexafloride, SF6
Chroflourocarbon, CFC

  CO2 is the main concern regarding global warming and comes from energy sources such as coal fired power plants, gasoline combustion, as well as natural gas burning.
  CH4 is mainly a product of agricultural practices as well as garbage decomposition.  Farm animals release methane as a bi-product of the digestion process.
  NO2 sources are similar to those of CO2, as well as fertilizers.
  SF6 is produced as an industrial by-product and accounts for less than 1% of GHG emissions.
  CFCs gained recognition for the ability to deplete the ozone layer, but are also dangerous GHGs.  Sources of this gas are mostly aerosol products and refrigerants.  Luckily, this gas is highly regulated, so emissions are very small.  

  Global warming potential (GWP) is a measure of a gases' ability to trap heat in the form of infrared radiation.  It is typically expressed as a multiple of heat trapped compared to a similar mass of CO2.  The factor is calculated over certain time periods, usually 20, 100, or 500 years.  For example, methane can trap 56 times more heat than CO2 over a 20 year period, while CFCs are upwards of 10,000 times!

Slide #6: What is the greenhouse effect?

  The greenhouse effect is what is responsible for global climate change trends that are currently being seen.  Like the name implies. this effect is very similar to what is observed in a greenhouse, allowing plants to be grown year-round.

  A greenhouse works by allowing the sun's energy in the form of solar radiation through the glass.  Some of this energy is absorbed by the various plants and some is reflected back in the form of infrared radiation.  The kicker here is that infrared radiation has a very long wavelength, while solar radiation has a short wavelength.  The infrared radiation isn't able to travel through the glass and thus is trapped inside.  The trapped energy translates into a heating effect inside the structure, so the space inside is warmed.

  The same effect is happening on earth, but with the glass replaced with green house gasses like CO2 and methane.  These gasses trap some of the infrared radiation and like as a blanket.  This warming is what has the potential for catastrophic effects.  

Slide #5: If the current energy profile of the world is sustained, what impact will it have on the environment?

  If the world's energy profile is sustained, that is, burning high amounts of fossil fuels as the main source of energy, many adverse environmental effects will be realized. The IPCC summary report to lawmakers highlights some of the potential environmental impacts of climate change.  If current emission trends continue, destruction of ecosystems affected by rising sea levels, as well as ecosystems effected by changing rainfall patterns, are likely to occur.  

  Another issue identified in the IPCC report is the increasing acidification of the oceans.  This decrease in pH value is expected to have a negative effect on shell forming organisms as well as all species that are dependent on them.  

  Finally. besides climate change, severe weather instances are likely to increase with continued upward trends of  GHG emissions.  The increasingly volatile weather pattern will put a great strain on much of the human population.

 

        

What is sustainability?

Sustainability from an energy standpoint is the ability to create energy without depleting a resource in a foreseeable way. This also requires the ablitiy to manage our waste. The ability to deal with our waste in such a way that is beneficial to ourselves is a sustainability factor.
The use of renewable resources is an ideal example to this definition, the harvesting of energy from resources that can be replenished quickly without producing waste. To maintain a equilibrium of resources and antiquity provide energy development is sustainability.

Why should we think about energy?

Energy is necessary for our society and civilization. Energy is being consumed at a rapid rate, on average 1,460 watts per day per person, in the USA according to the U.S. Energy Information Administration (http://www.eia.gov/cfapps/ipdbproject/iedindex3.cfm?tid=2&pid=2&aid=2&cid=AS,CA,CH,FR,GM,IN,JA,RS,UK,US,ww,&syid=2004&eyid=2008&unit=BKWH). The concern we should have is that the high consumption needs are being met using nonrenewable resources. Wikipedia claims that about 19% of the global energy production is produced from renewable energy resources, leaving over eighty percent of the energy to be produced with nonrenewable matter. In Professor Udaykumar's lecture he stated that with the current use of petroleum the supply would only last another 100 years, which that is roughly 35% of our energy consumption. So, the end is relatively near for the consumption of fossil fuels and other resources that are not renewable, and since we use these products to create energy we should be concerned that these methods of energy production will not be around in a foreseeable future.