Sunday, July 26, 2015

The inescapable future of fossil fuel combustion

      
Gasoline engine and oil well, circa 1900


Hydrocarbons as Energy?


In the last 100 years human mobility and energy production was revolutionized thanks to petroleum based fuels and internal combustion engines. Today’s quality of life is clearly an outcome of finding and utilizing fossil fuels that appear in abundance from today’s perspective. Yet, I would argue like many others, that as much as it was a great choice for humanity to do it for over 100 years, going forward our dependence on fossil fuels as an energy choice should be progressively and quickly replaced with renewable energy and majority of hydrocarbons should be preserved for future generations. At the same time, I also believe that the oil and gas industry can have a great long term future but, not as an energy supplier, but as a supplier of hydrocarbons (plastics, carbon fiber etc) for everyday, long life cycle products that are sustainable, safe, can be infinitely reused, recycled, repurposed and kept as a source of material for every aspect of life and for a very long time. If we use hydrocarbons in this manner they will become a virtually inexhaustible resource, unlike if we were to continue using them as we do today, primarily as a one time source of energy.


Efficiency of Use


For me the turning point was when I realized how inefficient using fossil fuels as an energy source actually is. In the process of using fossil fuels (a nonrenewable resource that can have other uses) we only recover and utilize only around 18% of the energy. This looks to me like a long term, dead-end strategy at the expense of the generations to come.  You are probably thinking that I am out of my mind; the fossil fuels we use for energy today are clearly used with greater efficiency than 18%, and yes, this is what I thought until I did the math.


The Math


Let me explain using the efficiency of gasoline and diesel consumption for vehicles as this is the most common use of petroleum products today. Around 70% of every barrel of oil is converted to gasoline and diesel as per Chart 1 below



To extract crude oil, transport it to the refinery and to produce gasoline we require energy.
Lets follow the path based on U.S. Department of Energy, Argonne National Laboratory study (https://greet.es.anl.gov/publication-high-octane-various-shares):


Energy Efficiency
Crude Extraction
98.0%
equivalent of 2% of energy in crude is used to extract oil from the ground.
Crude Transportation
98.5%
equivalent of 1.5% of energy in oil leaving the oilfield is used to transport oil via pipeline, rail car or truck to refinery.
Crude Refining
87.50%
equivalent of 12.5% of energy in the oil arriving at the refinery is used to refine oil into various products.

Each of the steps above uses combustion within the process, which is only 30% efficient at best. Hence at each step there is a loss of 70%.
Fuel to Distance Traveled
21.5%
78.5% of gasoline/diesel energy in the vehicle tank is lost due to thermodynamic limitations of cyclic engine, internal friction and parasitic losses




Another way to look at this…...
15.5% of energy in crude oil is used to get it from the reservoir to the tank in the vehicle (1-(0.98 x 0.985 x 0.875)) = 0.155 = 15.5%).  This energy is generated with combustion, direct or in stationary ICE, which at best is 30% efficient in converting energy to work. So in the end, most likely only 4.7% is actually used to convert crude oil into gasoline, and 10.8% is lost as heat (wasted).


Once the fuel is in the tank of the vehicle, due to the thermodynamic limitations of ICE we harvest on average only 21.5% of the energy of the fuel in the tank and convert that to distance traveled, again the rest is lost mostly as heat. From the original crude to distance travelled the overall efficiency is 18.2% (0.98 x 0.985 x 0.875 x 0.215= 0.182)


So in the end around 18.2% of crude energy is converted to distance travelled, 4.7% of crude energy is used to convert crude to gasoline and diesel, 10.8% of energy is wasted during the process of conversion and 66.3% is wasted in the vehicle. Total waste is (66.3% + 10.8% = 77.1%). That means that 77.1% of the energy is wasted in the process! AND the energy obtained is from a non-renewable and finite resource.




Even if  we had 100% efficient internal combustion engines due to the thermodynamic limit of 37% (The Carnot Limit, http://newsoffice.mit.edu/2010/explained-carnot-0519, https://en.wikipedia.org/wiki/Carnot_cycle ) we could never get more than 37% of energy from hydrocarbons to power our cars and trucks.


FUELS OTHER THAN CRUDE


Biofuels?


We could use biofuels to power our ICE or fuels generated from CO2  rather than gasoline, diesel, CNG or LNG. However, the efficiency of making biofuels and the land requirements are dependent on the type of source biomass.  Let's first look how much land we would need to produce enough biomass to produce the energy required today to power all internal combustion engines. I will use U.S. data to demonstrate.




Typical sources of biomass for biofuel are: soybeans, corn, sugarcane and algae. To produce enough soybeans to replace all gasoline and diesel in U.S. we would require 150% the area of the United States, corn - 15%, sugarcane 7% and algae 1.2%. Even using algae would require an area roughly between the sizes of the state of Arkansas or Main (http://biofuel.org.uk/land-use.html). Growing biomass to produce biofuels not only requires land, but also fertilizers, water and energy. It would be much more sensible to use the land to grow food, for recreation or nature reserves to preserve biodiversity and for the benefit of everyone rather than producing biomass and converting it to fuel.


On the other hand, producing biofuels from all waste biomass is a great idea, but the total amount of waste biomass is significantly too small to make any sizeable dent in our energy needs.


E-diesel from renewable power?


There are companies that plan to produce synthetic diesel or E-diesel using renewable power to generate hydrogen from water and capture CO2 from the air (https://en.wikipedia.org/wiki/E-diesel). I did not perform an efficiency calculation but considering that the process will be energy intensive as it is based on the Fischer-Tropsch process (http://www.elobio.eu/biofuels/fischer-tropsch-diesel/) and burning E-diesel will only be 19% efficient (just as in the original process) this approach will not fix the problem. Additionally, it seems like a very silly idea to use clean, renewable energy and convert it to a very inefficient and dirty fuel.



If the United States (I do not have good data from Canada) would replace all gasoline and diesel use with solar power electricity and convert to electric cars with 80%+ efficient powertrain and lithium-ion batteries, they would only require around 3,700 sq mi for the installations (or 0.1% of the total area of the US or an area the size of the Delaware and Rhode Island, http://www.nrel.gov/docs/fy13osti/56290.pdf). Amazingly, this area can be a barren desert or roofs of existing buildings, will never require water, fertilizer, additional energy etc. Batteries can be recycled and material from old batteries can be used to produce a new ones. Yes, the storage/battery technology is already available, all we lack is political and social will to go ahead.


More and more people make choices that will result in long term improvements to our environment, our quality of life and profitability of our businesses. But to achieve our goals we need to reject the status quo, no matter how comfortable it is, and pursue sound opportunities for change. So, when investigating new technologies I come across an idea that requires combustion (especially ICE), it is quickly clear to me that investing in anything that uses such an inefficient and wasteful process will not get us closer to our goal, but will actually perpetuate the status quo.  By understanding the process it is easy to critically assess ideas/technologies and to make sound decisions that consider PLANET and PEOPLE and PROFIT.



It is time to embrace a more sustainable uses of hydrocarbons!

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