Cleaner, More Efficient Cars,Trucks and Ships Using Methanol Engines

Transcription

1 Cleaner, More Efficient Cars,Trucks and Ships Using Methanol Engines Daniel R. Cohn MIT Energy Initiative Twelfth Carl M. Franklin Lecture on Science and Society USC February 20, 2015

2 Transportation Fuel Issues Energy Security Dependence on oil-derived fuels: gasoline, diesel Oil price volatility: $200 Price/bbl $150 $100 $50 $

3 Transportation Fuel Issues (cont d) Urban air pollution: particulates, nitrogen oxides Greenhouse gases: primarily CO 2

4 Engine Types Spark ignition Compression ignition

5 Spark Ignition (SI) Gasoline Engines The engine used in cars and light duty trucks An fuel/air mixture is ignited by an electrical spark. Unwanted detonation (knock) limits efficiency. Very low air pollution is enabled by a low cost, highly effective exhaust treatment system.

6 Compression Ignition Engines (Diesel) The engine used in heavy duty trucks and ships An air/fuel mixture is ignited by the compression of a piston. ~ 30% higher efficiency than the spark ignition gasoline engine (Main motivation for diesel engines.) ~ 10X higher air pollution emissions than the gasoline engine (Unless expensive advanced exhaust treatment and low sulfur fuel are used.)

7 Methanol as an Engine Fuel Room temperature liquid alcohol fuel (CH 3 OH) Works in spark ignition engines ( and can also be used in compression ignition engines) The least expensive liquid fuel to make from natural gas and coal, or renewable sources Special features enable large efficiency gains in spark engines for clean cars and trucks

8 Methanol From Renewable Sources Renewable methanol can be made from: - Municipal solid waste and other wastes - Forest and agricultural waste - Dedicated biomass plantations - Electricity from solar, wind or nuclear Could substantially reduce CO 2 from liquid transportation fuel if economically competitive.

9 China Presently Uses Methanol in Gasoline Blends Primarily used in cars to reduce gasoline demand Low concentration blends M15: 15 % methanol by volume (like E10 in US) Made from coal Demand has been been driven by economic advantages (lower oil prices could change this)

10 Methanol Advantages for Higher Efficiency 1. Removes knock limit on spark ignition engines. Knock is caused by unwanted detonation that can damage the engine. 2. Enables highly effective recovery of energy from exhaust heat.

11 Methanol Removal of Knock Limit: Intrinsic Super-high Octane Fuel Octane number (ON) is measure of knock resistance (Regular gasoline ON is 87; premium ON is 93.) Methanol fuel has intrinsic ON of 110. ON increases to ~130 when methanol is directly injected into the engine as a liquid. (Methanol has an exceptionally strong vaporization cooling effect.)

12 Removal of Knock Limit Allows Higher Efficiency Higher compression ratio - Greater compression of fuel/air mixture in cylinder increases thermodynamic efficiency Higher turbo charging pressure - Provides more fuel and air in cylinder. -A smaller turbo charged engine can provide the same power as a larger engine

13 Downsized Heavy Duty Truck Engine Using Directly Injected Methanol The methanol engine will have the same torque and efficiency as a diesel, but is 40% smaller (A 9L diesel engine can be replaced by a 5.5L methanol engine.) has 30 % more power than a diesel.

14 Energy Recovery from Exhaust (Bromberg and Cohn) More than 50% of engine energy is lost in exhaust gas and engine coolant. Heat is absorbed by reforming (converting) methanol into a hydrogen-rich gas which now has more energy than methanol and is combusted in the engine. Additional efficiency increases from use of higher temperature of methanol and faster fuel burn

15 Energy Recovery From Exhaust Heat HEAT EXCHANGER /REFORMER Low temperature catalytic reforming CH 3 OH -> 2H 2 + CO (hydrogen-rich gas)

16 Use of Metallic Foam to Capture Exhaust Heat Energy Additional surface area of foam improves exhaust heat transfer to gas, but high porosity limits thermal conductivity. This drawback is removed by combining foam with fins that have high thermal conductivity Test unit is under development at MIT.

17 Foam on Fins Heat Exchanger for Exhaust Heat Recovery Efficient, compact heat exchanger design Foam metals have high surface heat transfer coefficients but low thermal conductivity Fins have high thermal conductivity

18 55%- 50%- Super-efficient Spark Ignition Methanol Engines (Similar efficiency to fuel cell propulsion) Efficiency gain relative to standard gasoline engine 40%- 30%- 20%- Diesel engine Turbocharging and downsizing exhaust heat recovery 10%- High compression ratio Removal of knock limit (higher octane) Exhaust heat recovery

19 l Finding an Alternative to Diesel Is Particularly Urgent Major urban air pollution problems (nitrogen oxides and particulates) in countries using high pollution diesel trucks, e.g., China, Latin America Ships do not have any pollution controls in place. Potential shortages in diesel availability because of refinery limitations and increased demand especially in Asia. Could result in higher prices for diesel lll

20 Diesel Replaces Gasoline as Number One Global Transportation Fuel In 2020 ExxonMobil Outlook for Energy: A View to 2040

21 Evolutionary Deployment Of Super-efficient Methanol Truck Engines 1. Use of present spark ignition engine technology - Same efficiency, torque and cost as high pollution diesel engine - Greater than 90% reduction in particulates and NOx relative to high pollution trucks (China, other countries) - Option for operation primarily on gasoline 2. Future use of advanced exhaust heat recovery technology % higher fuel efficiency than diesel - Lower fuel cost and greenhouse gas emissions - Now being developed at MIT with support from Arthur Samberg Energy Innovation Fund

22 Comparison of Spark Ignition Methanol Truck Engine To High Pollution Diesel Engine* Methanol Existing Spark Ignition Engine With Advanced Exhaust Heat Recovery Efficiency and torque ~ 20-25% efficiency NOx and particulates > 90% > 90% Vehicle cost ~ +$5-10,000 Retail fuel cost in $/dge ($ per diesel gallon equiv ) Same $4.00/dge Same $4.00 /dge Fuel cost (Efficiency-corrected $/ dge) ~ $0.70 $0.80/ dge Power 30% 30% * Diesel engine without state of the art exhaust treatment and low sulfur fuel

23 Price Volatility Challenge To Use of Methanol As Substitute Fuel Wholesale price of diesel presently lower than methanol on energy basis Can remove economic motivation for diesel substitute However, there is economic motivation for use as efficiency booster, particularly for leveraged boost of gasoline engine efficiency

24 Octane Boosting of Gasoline Engines - Leveraged methanol use to increase efficiency of much larger amount of gasoline; substantially increases methanol value and allowed price - Use of small amount of methanol for on-demand octane boosting, thereby enabling higher efficiency - Provides efficiency advantages of diesel engines along with emissions, cost and power advantages of gasoline engines

25 Alcohol Octane Boosted Gasoline Engines (Bromberg, Cohn, Heywood) Use of small amount of alcohol ( methanol or ethanol) from second tank to prevent engine knock that would otherwise occur at high torque On-demand octane number (ON) can be increased to 130 (vs. 88 in regular gasoline and 93 in premium) - Could use lower cost, lower octane gasoline ( < 88 ON) Enables increase in gasoline engine efficiency to diesel-like high efficiency ( ~ 30 % higher than conventional engine)

26 Alcohol Octane Boosted Gasoline Engine Compared to Conventional Gasoline Engine 5.4 liter 2 liter Conventional Gasoline Engine Alcohol Boosted Gasoline Engine: high compression ratio, highly turbocharged

27 Refueling of Second Tank Need less than 15 % methanol by volume (8 % by energy) for cars and short haul trucks Methanol can be provided by: Pump Containers of methanol and water Onboard separation from low concentration blend

28 Onboard Fuel Separation Provide alcohol by onboard separation from low concentration blend with gasoline (ethanol from E10, methanol from M15) Substantial recent progress in onboard separation of ethanol from E10 - Honda - Corning/Exxon/Toyota

29 Honda Onboard Separation System for Ethanol Boosted Engine Membrane separation E68 ( 68 % ethanol by volume) separated from E10 25 % efficiency increase indicated in engine tests H. Kato, K. Kuzuoka, Y. Kato, Research on Engine System Making Effective Use of Bio-Ethanol-Blended Fuels, 2013 JSAE Annual Congress, May 2013, JSAE

30 Status of Alcohol Octane Boosted Gasoline Engines High efficiency capability established in engine tests and computer simulations at Ford, Honda and MIT Applications - Cost effective means to obtain higher efficiency in cars and light trucks (more cost effective than hybrid) - Gasoline alternative to diesel for heavy duty trucks (lower cost, cleaner, more powerful)

31 Incremental Cost vs. Efficiency Gain for US Large Car or Pickup Truck (350 hp engine)

32 Gasoline Truck Engine Using Methanol Octane Boosting vs. High Pollution Diesel Engine* Efficiency & torque similar to diesel NOx and particulates reduced by > 90% Vehicle cost Fuel cost Power similar similar ~30% more than diesel *Diesel engine without NO x and particulate after treatment and availability of low sulfur fuel

33 Burn Boost Methanol from second tank used is also converted into hydrogen-rich gas that is combusted in engine Increases burn speed at low torque; enables ultra dilute operation (lower ratio of fuel to other molecules) Increases efficiency by ~ an additional 10 % Additional use of ~ 15 % methanol by energy

34 Turbo Gasoline Engine Using Methanol Octane and Burn Boost Efficiency gain relative to standard gasoline engine 40%- 30%- 20%- Diesel engine Turbocharging and downsizing 10%- High compression ratio Removal of knock limit using octane boost Burn boost

35 Flex Fuel Gasoline Engine with Alcohol Octane And Burn Boost

36 Flex Fuel Super-Efficient Methanol Engine in Short Haul Trucks Methanol operation: 25 % efficiency gain over diesel Methanol octane and burn boosted operation: 15 % efficiency gain over diesel

37 Summary: Methanol Methanol is most efficiently made and lowest cost liquid fuel produced from natural gas and coal Also has important potential for greenhouse gas reduction as renewable fuel made from waste and biomass; or from electricity from solar and wind

38 Summary: Spark Ignition Methanol Engines Using presently available technology can provide >90 % reduction in air pollution relative to high pollution diesel trucks used in China and other countries Using advanced exhaust heat recovery can provide 25% efficiency gain over diesel truck engines - Greater efficiency results in lower greenhouse gas emissions

39 Summary: Methanol Boosted Gasoline Engines Methanol boosting of gasoline engine provides a leveraged way for a small amount of methanol to considerably increase the efficiency of gasoline use. On-demand octane boosted gasoline engines can provide diesel- like high efficiency with lower cost, lower emissions and more power in cars and trucks. Adding on-demand burn boost can enable gasoline engine efficiency that is % greater than diesel in short haul trucks.

40 Conclusions Cleaner and more efficient methanol engine technologies can be an important part of the solution to global transportation fuel issues They can be particularly important in reducing diesel fuel use