This page contains an overview of the candidates for the world's energy in the future along with their advantages, disadvantages, and likelihood of working.

  1. Solar
    1. Photovoltaic Systems
      Description:
      Photovoltaic cells convert the sun's energy directly into electricity. Many types of these exist. Silicon-based systems are fairly efficient, but expensive and rigid. Organic-based solar cells are cheaper and flexible, but are not very efficient. Half the cost of solar cell home units is the installation.
      Advantages:
      Pollution free during operation.
      Disadvantages:
      1. Expensive, 2 to 5 times the cost of conventional energy
      2. Creating the solar cells takes significant energy and creates pollution
      3. Deployment takes a large surface area
      4. Only works when the sun shines
      Current Cost: 15-35 cents/KWh
      Future:
      Near term: solar cells will continue to be a niche market until further research brings cost down.
      Long term (10 yrs): very bright.

    2. Photooxidation of Water
      Description:

      The splitting of water into hydrogen and oxygen is call Photooxidation. Water filled panels with the right catalyst can use the sun's rays to create hydrogen from water. This is similar to photovoltiac cells, but the output is hydrogen gas instead of electricity. This is still a very new technology for commercial use. The best efficiency is 42%.

      Advantages:
      1. Clean, carbon-neutral renewable energy
      2. Unlike photvoltiac systems, photooxidation can store energy easily as hydrogen gas for use later.
      Disadvantages:
      1. Only works when the sun shines
      2. After production of the hydrogen gas another step is needed to create electricity either by burning in an engine or turbine, or in a fuel cell.
      Current Cost: ???
      Future: bright

      Long term (20 yrs): bright.

    3. Concentrating Solar Power (CSP)
      4. Description:

      Concentrating Solar systems focus sunlight onto a working fluid. Today CSP has three forms. Solar Towers use arrays of mirrors to focus sunlight onto a central tower that contains a fluid that is heated to run a turbine. Parabolic troughs focus sunlight on a tube of liquid that is then used to turn a turbine. Stirling systems use mirrors to focus sunlight to the hot side of a Stirling engine.

      Advantages:
      1. No green house gases emitted.
      2. Once built, no fuel costs to keep running
      Disadvantages:
      1. Expensive capital costs upfront
      2. Only works when the sun shines
      Current Cost: 15-20 cents/KWH.
      Future: fair.

      Long term (20 yrs):fair.

    4. Ocean Thermal Energy Conversion

      Details here.

    5. Solar chimneys

      graphics.

  2. Wind
    Description:
    2006-12-16-Windmill.jpg

    Wind energy is currently harvested from large windmills. The exciting aspect of wind power is that it is almost cost competitive with traditional forms of power generation. No one expects wind to provide all the power for a grid, but it is a nice supplement. Some of the disadvantages are being addresses with off-shore wind farms.

    Advantages:
    1. Renewable
    2. Operates with no pollution
    3. Operates with no production of green house gases
    4. Almost cost competitive with coal and gas
    Disadvantages:
    1. Can be noisy and unsightly
    2. Intermittent, most windmills operation at 25 percent of capacity
    3. Cannot be depended on for peak load generation
    4. Has a nasty tendency to chop up birds and bats
    5. Capital intensive
    6. Best locations are often far from populated areas requireing the building of expensive power lines
    Current Cost:
    5-7 cents/KWh
    Future:
    Very bright. With better engineering the cost is dropping significantly every decade.
  3. Geothermal
    Description:

    Geothermal uses the heat inside the earth to produce electricity. Typically this is done by pumping water into wells, letting the earth heat the water, and pumping the hot water back to the surface to be used to drive generators to produce electricity.

    Advantages:
    1. No fuel is needed.
    2. Electricity can be produced constantly, unlike wind and solar.
    Disadvantages:
    1. Expensive - although the fuel is free, the capital costs can be enormous.
    2. Only feasible where the earth's crust is thin
    3. Many dissolved salts and gases come out of solution when the pressure on the water is lowered. Arsenic may pollute the local vegetation. Gases like Hydrogen Sulfide can be released.
    Current Cost:
    Future:

    Long term (20 yrs):fairly good.

  4. Biomass
    1. Traditional Ethanol and Cellulosic Ethanol
      Description:

      Ethanol is produced by fermenting crops like corn or switchgrass.

      Advantages:
      1. Renewable
      2. Ethanol has a fairly high energy density
      3. Can be blended with gasoline and used in automobiles with minor adjustments
      Disadvantages:
      1. The current fermentation of corn does not produce much more energy, than it takes to make the corn. Switchgrass and other cellulosic ethanol can be much more efficient.
      2. The demand for corn based ethanol has driven up the price of food
      3. Ethanol cannot be transported in pipeline since it collects water
      4. Ethanol has a lower energy density than gasoline
      Current Cost:
      Future:
      short term: marginal
      Long term (20 yrs):Bright. With the right bacteria all types of agricultural waste like corn husks and lawn trimmings could be converted to ethanol, but it will take some work to find or engineer the right bacteria.

    2. Biodiesel
      Description:

      Biodiesel is produced by crushing plant material like soybeans and palms

      Advantages:
      1. Renewable
      2. Flexible - biodiesel can be made from a variety of plants
      3. Can be burned in current diesel engines with minor adjustments
      Disadvantages:
      1. Will drive up food prices
      2. Will take up a lot of land to grow the plants
      Current Cost: almost competitive with conventional diesel
      Future: Bright.

      Long term (20 yrs):Bright.

    3. Bacteria

      Biology is a very exciting frontier for energy creation. We have not yet scratched the surface on what bacteria can do. Terminates have over 20 different bacterium in their gut to convert wood to energy. With a little selective breeding (or genetic engineering for the impatient), bacteria could convert waste into usable energy for us.

      1. Hydrogen Producing.
      2. Methane Producing

        Methane is produced by letting bacteria digest organic material and collecting their by product

      3. Direct Current

        Some bacteria can create electricity directly.

      4. Burning
  5. Ocean
    1. Wave
      Description:

      A few types of designs exist for harnessing the energy of waves. Some are buoys in the ocean which generate electricity from being pushed up and down by the waves. Another type is a long snake-like series of tubes that are lifted up and down by the waves. A third type is on the seashore and rely on waves to push air into a pipe which drives a wind-turbine.

      Advantages:
      .
      1. Clean and renewable
      2. Sixty percent of the world's population lives within 40 miles of a coast
      3. Waves are more reliable than the wind and can be predicted more accurately
      Disadvantages:
      1. Costly, more expensive than wind
      2. Not reliable
      Current Cost:
      Future:

      Long term (20 yrs):.

    2. Tidal
      Description:

      Tidal power captures the energy of water rising and falling with tides. This can be done with underwater turbines or by damming a bay.

      Advantages:
      .
      1. Clean and renewable
      2. Unlike wind and waves, the tides are predictable
      Disadvantages:
      1. Fairly expensive
      2. Difference in tides is not very high so power generation is not as efficient as in tall dams
      3. Timing of tides does not correlate with peak demand
      4. May effect shipping
      5. May prevent dispersement of industrial wastes
      Current Cost:
      Future:

      Long term (20 yrs):.

    3. Thermal energy
      Description:

      In the tropics the top layer of water is hotter than the lower layers. The temperature difference drives the energy production. In ocean thermal energy production the hot water is used to turn a turbine by boiling a liquid with a low boiling temperature and then condensing the gas back to a liquid with water piped from the bottom of the ocean.

      Advantages:
      .
      1. Clean and renewable
      2. Very predictable
      3. No fuel needed
      Disadvantages:
      1. Fairly expensive in capital cost
      Current Cost:
      Future:

      Long term (20 yrs):.
  6. Hydrocarbons
    1. Shale Oil

      The Bureau of Land Management estimates the US oil shale reserves at 800 billion barrels of oil, three times the proven oil reserves of Saudi Arabia. "Shale Oil" is not really shale or oil, but kerogen, an uncooked oil, embedded in a hard rock called marl. The kerogen can be heated to resemble oil. The big problem is getting it from ground. Shell Oil is running a pilot plant in Colorado using heaters to loosen the oil and gas from the rock. The test plant gets twice as much energy than it consumes heating the rock. Shell's pilot should finish in 2010.

    2. Coal To Liquids (CTL)
      Description:
      Synthetic gasoline and diesel can be produced from coal with processes like Fischer-Tropsch. Long term this will provide the ceiling for oil prices. The Germans and Japanese used this process in WWII.
      Advantages:
      1. The U.S. and China have vast coal reserves.

        Oil is 2 percent of the US's energy reserves, 3 percent is in gas, and 95 percent is in coal. Just Illinois' coal resources have more energy than all of Saudi Arabia's and Kuwait's oil reserves combined.

      2. Less polluting than burning coal.
      3. Current diesel engines can burn it.
      Disadvantages:
      1. If oil goes below $30, synthetic gasoline is too expensive.
      2. Strip mines aren't pretty
    3. Tar sands
      Description:

      Tar sands are thick hydrocarbons dispersed in sandy soil. They cannot be pumped directly like oil, but must be processed in other ways like digging the soil, transporting it to a refinery, and cooking the hydrocarbons into something useful. Canada is producing 1 million barrels of oil per day from tar sands and can still scale up the process.

      Advantages:
      1. Located in Canada
      2. Provides a reliable source of petroleum
      Disadvantages:
      1. Causes environmental damage
      2. Produces more greenhouse gases than normal refining of oil
      3. Uses a lot of water
      Current Cost:
      Future:

      Long term (20 yrs):.

    4. Methane Hydrates
      Description:

      Methane gas trapped in ice chunks underneath our oceans and land is called Methane Hydrates. The pressure of the oceans or land above it keep the methane trapped in ice. If you remove a chunk of the ice and place it in our atmosphere it will crackle as the gas escapes the ice. The ice can contain 180 times its volume in methane gas. You can hold a match to it and set it on fire.

      Advantages:
      1. We have a plentiful supply.

        "There's more energy potential locked up in methane hydrate formations across the world than in all other fossil energy resources combined," - Brad Tomer, director of the Department of Energy's Strategic Center for Natural Gas and Oil.

      2. The supply is close to North America.

        Just of the coast of the Carolinas alone is a field of methane hydrates equal to over a hundred times our annual use of natural gas.

      Disadvantages:
      1. Although two methods of extraction: depressuration and hot water injection, have been proven, we don't have an economical method of producing the methane.
      2. Tsunamis created by a collapse of the sea floor could be a possible side effect or removing the gas.
      Current Cost:
      Unknown
      Future:
      good
      Long term (20 yrs): good.

  7. Thermoelectric
    Description:
    Thermoelectric materials make electricity from a temperature differential. Heat one end of a thermoelectric bar and electrons flow to the other side. This could be very useful in capturing the waste heat from a car engine to recharge the battery or run the headlights. Some satellites use Radioactive Thermoelectric Generators ("RTG"s) for power. A radioactive source like plutonium create the heat to drive the thermoelectric device.
    Advantages:
    Temperature differences exist all around us.
    Disadvantages:
    Efficiency is very low.
    Current Cost:
    Too high
    Future:
    Niche player
  8. Nuclear
    1. Fission
      1. Traditional Fission from Uranium
        Description:

        Splitting the Uranium atom releases energy that is used to create steam to turn electrical generators.

        Advantages:
        .
        1. No green house gases created
        2. We have a plentiful supply of Uranium from reliable sources.
        3. Reactors produce constant energy with little down time.
        Disadvantages:
        1. Possibility of an accident with massive loss of life and property.
        2. Disposal of waste is still a concern. Waste is toxic for millennia.
        3. Material for weapons can be diverted from a reactor.
        4. Reactors have an initial high capital cost.
        Current Cost:
        5-7 cents per KWH
        Future:
        bright, especially with global warming concerns.
      2. Pebble-Bed
    2. Fusion
      1. Traditional Magnetically Confined Plasma (Tokamak)
        Description:

        Plasma is superheated in a donut shaped 'bottle' and forced to undergo fusion.

        Advantages:
        1. Little radioactive waste
        2. Theoretically very promising
        Disadvantages:
        1. This technology has always been '20 years' from deployment.
        2. Lots of technical hurdles to overcome
        Current Cost: N/A
        Future: 20 years away

        Long term (20 yrs): fairly good.

      2. Laser Ignition. Example is Sandia's Z machine.
        Description:

        Laser Ignition uses many lasers to compress a pellet of deuterium and tritium to produce fusion.

        Advantages:
        1. Little radioactive waste
        2. Fuel is plentiful and cheap
        Disadvantages:
        1. A power plant using this technology is still 20 years away.
        Current Cost: N/A
        Future: lots of details to work out

        Long term (20 yrs): very bright.

      3. Thorium

        Thorium sits two elements away from Uranium in the periodic table and can be used to produce electricity like Uranium, but without many of the drawbacks. Thorium reactors cannot maintain their own fission, so meltdown accidents are not possible. Thorium is 500 times more plentiful than Uranium. The major issue is how to kick-start and maintain a thorium reactor.

      4. Inertial Electrostatic Confinement (IEC) video.
      5. Levitated Dipole
        6. .
      6. Bubble
      7. Cold
      8. Crystal
  9. Unusual and Highly Speculative
    1. Capturing lightning strikes
    2. Man-made tornadoes.
    3. Free energy or vacuum based systems

Energy Storage Solutions

Many of the renewable energy system need a storage mechanism to be really useful. Below are some methods to store energy:

  1. Flow batteries
  2. Flywheels
  3. Supercapacitors
  4. Superconducting coils
  5. Compressed air

    Energy can be stored as compressed air in caverns, aquifers, depleted natural gas wells. When needed the compressed air is directed to turbines to generate electricity.

  6. Pumping water uphill
  7. Molten Salt

    Salt can store excess heat from solar thermal collectors and be used at night to generate steam to make electricity. The salt is corrosive and it's heat must be used within days.

  8. Hydrogen gas

    Spare electricity is used to split water into hydrogen and oxygen gases. When electricity is needed, the hydrogen is used to create electricity. Currently, ahum,.. the process is inefficient, but companies like ITM are reducing the cost.

Parting Thought:

The frustrating thing about providing energy is that it is all around us like the air we breath, but harvesting the power is elusive. Waves constantly pound our seacoasts, lightning dissipates vast quantities of electricity, sunlight falls gently on our planet, the wind blows ceaselessly, vast temperature differential exists just miles below our feet, but alas, all goes unharnessed. Hopefully in the future one our children will take energy production like we do clean water - just turn on the spigot and it's there.

Miscellanous Info:

  1. Transmission losses for electricity are 3% per 1000 kilometers.
  2. 10,000 deaths occur each year from mining coal.
  3. Electricity from coal-fired power plants costs 2-4 cents/kilowatt hour.
  4. The cost of crude oil is 70 percent the cost of gasoline.
  5. A lead-acid battery has a specific energy of 32 watt-hours/kg. A lithium-ion battery has 120 watt-hours per kilogram. EEStor's ultracapacitor is estimated to be 280 watt-hours/kg.
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