ethanol lecture

Solutions to the World’s Energy Crisis: 

Solutions to the World’s Energy Crisis Growing Energy?

The New Agriculture: 

The New Agriculture Brazil – sugar cane to ethanol US – corn to ethanol Europe – wheat to ethanol Can ethanol replace fossil fuels as an energy source? Is it a feasible solution to our dependence on foreign oil? Is it a feasible solution to global warming? Is it green?

Continue: 

Continue Are ethanol subsidies an good example of science directing politics or is it a bad politics getting in the way of science? Are there better solutions; algae, municipal waste, H2 fuel cells, solar energy, nuclear energy?

Corn to Ethanol (the process): 

Corn to Ethanol (the process) Growing corn (fertilizer, herbicide, pesticide, man power, seeds, irrigation) Harvesting corn (farm machinery, man power) Transport to ethanol plant Processing/distillation Co-products (dried grains, corn gluten feed and meal) as animal feed.

What makes it green (ideally)?: 

What makes it green (ideally)? CO2 emissions/per energy produced is similar to petroleum. However, CO2 released is recaptured by next years crops. So, there is no net CO2 added, unless you take into account the energy used in the process of farming corn and converting it to ethanol.

Thermodynamics: 

Thermodynamics The First Law The energy of the universe is constant You can not win The Second Law The Entropy of the universe is constantly increasing. The energy put into transforming the seeds into ethanol has to be greater than the energy content of the ethanol. You lose heat in the process as entropy. You can not break even What are the energy inputs? Energy outputs? Let’s do and energy (and mass balance).

The Case Against Ethanol (Patzek): 

The Case Against Ethanol (Patzek) Energy balance (more energy from fossil fuels are used to produce ethanol from corn than the energy produced from burning the ethanol product from corn) Ethanol from corn is unsustainable (we are spending our precious entropy). Environmental impact (depletion of resources)

Entropy and Sustainability: 

Entropy and Sustainability To be sustainable a process must be Reversible Must only produce heat and no chemical waste. The heat produced must not exceed the capacity of the earth to dissipate the heat to the universe The burning of fossil fuels is not sustainable. Agriculture is not sustainable (nutrient depletion, soil erosion)

Energy Balance: 

Energy Balance Inputs, the energy required to produce the resources that goes into the production of ethanol from corn requires the energy from fossil fuels. This energy input can be estimated and summed. Compare this to the energy available from the ethanol product. Different investigators obtained different results and therefore different conclusions about the future of “growing ethanol”.

Energy Inputs: 

Energy Inputs Corn Production Ethanol Production

Corn Production: 

Corn Production Solar energy minerals Seeds, Fertilizer, pesticides, herbicides Irrigation fuel farm machinery manual labor Electricity Transport 2500 kcal/L ethanol produced (Patzek)

Ethanol Production: 

Ethanol Production Transportation of corn harvest to plant Distillation infrastructure Transporting ethanol product and co-products and waste purifying waste water Electricity Steam 4100 kcal/L ethanol produce

Energy output from ethanol: 

Energy output from ethanol Ethanol, 5130 kcal/L Co-products, ? Net: 5100-2500-4100 = -1500 kcal /L Or about 30 % more energy from fossil fuels goes into the production of ethanol from corn than the energy in the ethanol that can replace fossil fuel use.

Co-products: 

Co-products Gluten meal and gluten feed Replacement for soy bean meal – 1450 kcal/L Impact on cattle Impact on sustainability

Under estimate: 

Under estimate This does not take into account the costs of long term environmental remediation Another estimate states that it costs 1.8 gallons of gasoline to produce an amount of ethanol that has the energy equivalent of 1 gallon of gasoline. Ethanol has 63 % of the caloric value of gasoline

CO2 emissions: 

CO2 emissions Yes, CO2 is recycled by next years crop, but not fossil fuel inputs, which produce 6700 kg of CO2 per 1 ha of corn/ethanol farming. Burning an amount of gasoline equivalent to the amount of ethanol produced per ha would produce only 5100 kg CO2 1600 kg/ha extra CO2 is produced

Subsidizing the Corn/ethanol Industry: 

Subsidizing the Corn/ethanol Industry Corn subsidies to farmers, mostly large conglomerates National ethanol subsidies State ethanol subsidies Our natural resources $3.5 billion /yr

And even if all this was not true: 

And even if all this was not true 12% of US corn fields are devoted to ethanol providing less than 2% of our energy needs Very little capacity is left to make a meaningful dent in the energy crisis. So, can it ever be worth the tax payers money to grow corn for ethanol?

The case for ethanol: 

The case for ethanol What is wrong with the analyses of Patzek and Pimentel? Treatment of co-products Disagreements about input data Ethanol yield per dry corn Citations are lacking or do not match up or are based on old data not relevant to current practices Assumes no improvement in yield and energy efficiency going forward.

New metric: 

New metric Compare the petroleum used to create 1 MJ of gasoline to the petroleum used to create 1 MJ equivalent of gasoline Ratio is approximately 0.05 (or about 2 according to Patzek’s adjusted data). Patzek: 5-12 times more fossil fuel energy to produce corn ethanol than it does to produce gasoline of equivalent energy. How can these analyses be so different?

Switchgrass: 

Switchgrass The potential of switchgrass 1000 Gall/acre (665/400) Cellulose to ethanol Farrell predicts it has the potential to be a factor of 5-10 times more energetically efficient. Easier to farm than corn, requiring less energy input, provides excellent yield, potentially much more environmentally sustainable. 1 kcal input/11 kcal output of switchgrass Cost of producing ethanol from cellulose is very energy intensive (steam and electricity)

switchgrass: 

switchgrass Cellulose is difficult to break down Enzymatically Harsh chemicals Long reaction times/ need for sterile environment

sugarcane: 

sugarcane Double the yield of corn (130 vs. 71 GJ/acr·year) Year round growing season Waste use to produce energy to distill the ethanol Sustainable if one uses a 60 % efficient fuel cell.

Algae: 

Algae 10000 Gallons biodiesel/acre·yr Can use CO2 from power plants Can use dirty water Need for bioreactor ($$$?)

Fatty acids esters from algae: 

Fatty acids esters from algae Ethanol + Na → CH3CH2ONa, used as catalyst

Isolation of biodiesel: 

Isolation of biodiesel Ether and salt to remove glycerol, sodium, water centrifuge