The Road to Hydrogen Fueled Transportation ME 416/516

Transcription

1 The Road to Hydrogen Fueled Transportation

2 Why Hydrogen?!?! Haven t we been there, done that? Crash of the Hindenburg- 37 dead- Lakehurst, New Jersey, May 6, 1937.

3 Energy Security Problems 55% of US oil is imported, causing supply vulnerability and trade deficit $110 billion/year net petroleum imports- 1/4th of foreign trade deficit 57% of all oil goes for cars and trucks 38% of total US energy consumption is petroleum

4 Environmental Concerns Emissions from internal combustion engines include NOx, unburned hydrocarbons, particulates (smoke), CO and CO 2 NOx + hydrocarbons + sunlight = ground level ozone CO 2 is the primary greenhouse gas implicated in global warming

5 Possible Solution: The Hydrogen Economy Produce hydrogen (H 2 ) from other domestic energy inputs Store and distribute hydrogen to consumers Use hydrogen to power fuel cells (or possibly IC engines) with only water emitted in exhaust: H 2 + ½ O 2 H 2 O

6 Hydrogen Benefits Hydrogen is a colorless, odorless, tasteless, and nonpoisonous gas The combustion of hydrogen produces no carbon dioxide (CO 2 ), particulate, or sulfur emissions Burning H 2 in air produces nitrogen oxide (NO) emissions, but no NO if H 2 is burned in pure O 2 or used in a fuel cell Hydrogen is an energy carrier that allows ready conversion from various energy sources to vehicle fuel

7 Three BIG Challenges for the Hydrogen Economy 1. Making hydrogen cheap- now costs at least $2 to $3 for the equivalent of a gallon of gasoline (before taxes) compared to about $1 for gasoline 2. Economical storage and distribution of hydrogen 3. Cost effective vehicles- fuel cell power systems are estimated to cost 10 to 100 times more than internal combustion engines

8 H 2 Production Technologies Reforming hydrocarbons: CH 4 + 2H 2 O + heat CO H 2 From natural gas or other HC source Greenhouse gas Fuel Electrolysis: 2H 2 O + electric energy 2H 2 + O 2 Where do we get this?

9 H 2 through Reforming U.S. makes 90 billion m 3 of H 2 per year Used for fertilizer (about two-thirds of total production), hydrogenation reactions (like food fat), chemical feedstock, fuel for NASA Space Shuttle main engine and fuel cell power units, etc. Fossil fuel reforming is cheapest, but could use renewable biomass as input

10 H 2 through Electrolysis An electric current is used to separate water into its components- H 2 and O 2 Electrolysis does not use much water. The H 2 from a gallon of H 2 O could drive a hydrogen fuel cell vehicle as far as a gasoline vehicle travels on a gallon of gasoline Electrolysis is less energy efficient than reforming Electrolysis will meet environmental goals only if the electricity is from a renewable source

11 Renewable Electricity Sources Source: US DOE

12 U.S Energy Supply- Focus on Renewable

13 Renewable Electricity The two most promising forms of renewable power generation are solar power and wind power Challenge- a solar plant would take 4 years just to repay the energy used for its constitutive materials; 2 years for wind plant Sources: Above hydrogennow.org; below US DOE

14 How Much Solar Is Available? Source: US DOE

15 How Much Wind Is Available? Source: US DOE

16 H 2 from Fossil Fuels with CO 2 Sequestration Fossil fuels cause global warming through greenhouse gases (like CO 2 ) from combustion U.S. has huge coal reserves- could be used without global warming by sequestering CO 2 Separate CO 2 from exhaust and permanently store it in old oil or natural gas reservoirs, underground formations, or oceans CO 2 injection in oil/gas wells enhances recovery Sequestration adds 10 to 20% to cost of fuel

17 Novel Methods to Make H 2 from Renewable Sources Thermochemical water splitting uses chemicals and heat in multiple steps to split water Photoelectrochemistry uses semi-conductors (like photovoltaics) to split water with sunlight Photobiological systems use microorganisms to split water with sunlight Biological systems use microbes to break down a variety of biomass feedstocks into hydrogen Thermal water splitting uses very high temperature (~1000 C) to split water (plasma)

18 Hydrogen Storage- Tanks For shipping or on board vehicle storage- dewars (thermos flasks) for liquid storage at 20 degrees K above absolute zero, which is F metal hydrides, metals in which hydrogen dissolves in high quantities- low pressure tanks high pressure tanks ( ,000 psi) for gaseous, room temperature H 2 H compounds in which H 2 can be added at fuel station and stripped for use in fuel cells, e.g., sodium borohydride (borax)

19 Hydrogen Storage- Issues Hydrogen storage is challenging because H 2 is such a light, lowdensity gas US DOE technical goal: at least 6% of H 2 storage system for cars is H 2 itself, not container mass Storage of liquids requires extremely low temperature and extreme insulation Liquefaction adds 30 50% to cost Source: US DOE

20 Hydrogen Storage- Issues Metal hydrides are metals in which hydrogen dissolves in high quantities, so that high storage density is achieved at room temperature and modest pressures, but tank weight is a problem Hydrogen diffuses into metals over time, causing embrittlement and reducing strength Because they are so small, hydrogen molecules leak through pipes, valves and fittings more readily than other gases

21 Hydrogen Distribution Issues Local vs. large-scale production and distribution Production using on-board reformers, at the filling station, or in large plants On-board reformers add to vehicle cost, lower efficiency Production at large plants requires larger tanker trucks or new hydrogen pipelines Shell opens first liquid H 2 station in Tokyo, June 18, 2003

22 Hydrogen Fueled Vehicles Major types of vehicles: Hydrogen internal combustion engine (ICE) Hydrogen ICE hybrid electric Hydrogen fuel cell vehicles with reformer Hydrogen fuel cell without reformer Other fuel cell typesdirect methane, direct methanol, don t require hydrogen at all, but are not as efficient and do have CO 2 emissions Source: US DOE, Nissan

23 Hydrogen Fueled Internal Combustion Engines Use of H 2 as an IC engine fuel eliminates all major emissions (including CO 2 ), except NOx NOx is formed when high temperature causes some atmospheric nitrogen to react with oxygen If oxygen rather than air could be used as oxidizer zero emissions Best fuel economy obtained through hybridelectric technology, which allows regenerative braking and optimal ICE operation

24 Example of Hydrogen ICE: Ford Model U Concept Car Ford Model U has a 5000 psi storage tank that can hold 5 kg of H 2 Model U has a range of 175 miles 2.3 L engine has high compression pistons, hydrogen injectors, intercooled supercharger, specialized spark ignition Peak thermal efficiency is 38%, which is about 25% better than gasoline engine Under the hood of the Model U. Source: Ford

25 How a Fuel Cell Works Flow of electrons powers motor or charges battery Air compressor here Anode separates H 2 into individual protons (+) and electrons (-) PEM Source: Fuel Cells 2000, Moist air out

26 Fuel Cell Vehicles Schematic shows typical components of a fuel cell vehicle. Source: US DOE

27 More FCV s Most major automotive companies have active fuel cell research programs. Daimler-Chrysler Necar 1 50 kw Daimler-Chrysler Necar 2 75 kw Citaro FC Bus 205 kw Ford Focus FCV 75 kw Source (all): Ballard Fuel Cells

28 Other Fuel Cell Applications for Transportation One example of other fuel cell applications is this auxiliary power unit (APU) developed by the University of Alabama, Ballard and Freightliner Trucks The 5 kw fuel cell allows driver to use cab at night without idling the big diesel engine- this is clean, quiet, and fuel saving Ballard/UA/Freightliner award-winning fuel cell auxiliary power unit

29 The Big Picture- The Hydrogen Economy For large-scale fuel cell vehicle adoption for business/economic reasons, need: Affordable hydrogen, readily available Affordable fuel cell vehicles Now H 2 from fossil fuel is 2 or 3 times more expensive than gasoline; H 2 from renewable electrolysis is 5 to 6 times more expensive An IC engine now costs about $20/kW capacity; a fuel cell engine cost a minimum of $250/kW (mass-produced) and likely more

30 More Hydrogen Economy Is economics ($$$) all that matters? What if we could calculate the real cost of pollutant and CO 2 emissions and charge the user per ton emitted? This is called capturing the cost of externalities in economics. Clearly, achieving a clean hydrogen economy is not only a scientific and engineering challenge, but a political and social challenge as well. Where do we go from here?

31 The Technical Path Forward Hybrid electric vehicles!!! 2004 Toyota Prius. Source: Toyota.com

32 Hybrid-Electric Vehicle (HEV) HEV has an internal combustion engine (ICE) plus an electric motor, generator and battery Cruising, the ICE operates at a fuel-efficient steady speed to drive generator, which charges battery and powers electric motor to turn wheels For high acceleration, the ICE and electric motor both drive the wheels Regenerative braking and ability to turn off ICE rather than idling gives great efficiency Toyota Prius, Honda Insight, and Honda Civic Hybrid available; hybrid Ford Escape is coming soon

33 Example: New Toyota Prius SAE s 2001 and 2004 Best Engineered Automobile The new 2004 Prius has a 76 hp ICE, a 67 hp electric motor, and a 106 net max hp The Prius seats five in reasonable comfort, and will go from 0 60 mph in less than 12 s Prius gets over 50 mpg combined city/highway, and has a 500+ mile range with its 11 gal tank The new Prius starts at $19,995, and Toyota was making a profit on the 2003 model without corporate subsidy - not a concept car!! Technology is essentially same as for a fuel cell vehicle, except ICE is used instead of fuel cell

34 More Recent Hybrid News The second generation 2004 Toyota Prius is selling like hotcakes. Almost all of the approximately 40,000 production run for 2004 is spoken for- Toyota dealers say there is an approximate 8 month backlog now. Toyota has announced it will sell a hybrid-electric version of the Toyota Highlander in Winter 2005 that has faster acceleration than the current gasoline model plus gets a combined 28 miles per gallon. Toyota's Lexus has announced a hybrid version of the Lexus RX330 mid-size SUV that will be called the RX400h. It also promises better performance AND better gas mileage than the conventional model.

35 More Recent Hybrid News Ford is expected to begin selling a hybrid version of the small-to-mid-size Escape in late It is estimated to have 29 mpg city/40 mpg highway performance on the EPA mileage test. Ford has recently licensed about 30 of Toyota's approximately 300 patents on hybrid-electric technology. Honda announced it will be selling a hybrid electric version of the Accord in Fall 2004, which will be similar technology to that used in the current hybrid Insight and Civic models, but with considerably more power.

36 Local Effects One of the new vehicles expected to be built in the expanded Mercedes Plant in Tuscaloosa is the Vision Grand Sports Tourer. The trade show intro concept car had a diesel hybrid electric engine.

37 The Skeptics Problem with H 2 in stratosphere? Maybe it s cheaper to use fossil fuels plus CO 2 sequestration Is global warming real? Considering well-to-wheel fuel efficiencies does not favor H 2 fuel cells Is hydrogen safe?

38 Stratospheric H 2 Problem T. K. Tromp et al., Potential Environmental Impact of a Hydrogen Economy on the Stratosphere, Science, 13 June 2003, p Says if widespread fuel cell usage occurs with hydrogen leakage rates on the order of 10 20%, that ozone depletion, cooling, and other effects would occur in the stratosphere. Other hydrogen experts say that this rate of leakage is high by a factor of 5 to 10, and actual problems would be minimal.

39 CO 2 Sequestration; Well-to-Wheel Efficiency Some claim it makes more sense to use cheap fossil fuels (abundant coal) and sequester the CO 2 Like fuel cells, future CO 2 sequestration costs and effectiveness are hard to predict Several have demonstrated that it is more efficient to use diesel engine hybrid electric vehicles (and other technologies) than H 2 fuel cell cars considering the total energy costs of producing the fuels Decision goes back to the importance of minimizing pollution and CO 2 emissions

40 Hydrogen Safety Old saying- if the gasoline engine was invented today, it is too unsafe to be allowed on the market H 2 is a relatively dangerous fuel, but should prove at least as safe as gasoline (!) with sound engineering practice and codes More Hindenburg shots. Source: Vidicom-TV.com

41 Opportunities for Engineers Hydrogen transportation offers new environmental challenges for production, distribution, and use CO 2 sequestration, hydrogen pipelines, new H 2 productions are all about CE Fuel cell vehicles will ultimately involve many challenges in transportation engineering. Think of the entire automotive and fuel industries- reengineered!

42 Questions? GM s prototype fuel cell car, the Hy-wire, product of a billion dollar GM investment in fuel cell technologies Source: CBS News, GM