How might technology provide solutions?

This is an overview of the different technologies that can help reduce carbon dioxide emissions in our near and distant future. This is by no means comprehensive, but provides some of the key benefits and concerns regarding each technology. Ultimately, we will need a combination of many technologies to make a big difference both in the short and long term; no one technology will single-handedly eliminate the human impact on our climate.

Only Coal and Oil?

This is the hierarchy of the hydrogen-based fuels:
Coal < Oil < Natural Gas < Hydrogen Gas

Coal is the least efficient and emits the most CO₂, while Hydrogen Gas is (theoretically) the most efficient and emits no CO₂. Efficiency is defined as the amount of usable energy for every unit of energy put in: e.g. Putting in 1 unit of energy can convert coal (~35% efficiency) into .35 units of electricity for an appliance, the rest of the energy is wasted.

Natural Gas (methane):

• Benefits:
• 1 Carbon for every 4 Hydrogen atoms (i.e. less CO₂ emissions per unit mass)
• Can have up to 80% efficiency
• Changing all coal plants to natural gas would cut global CO₂ emissions by 30%--not bad, but not great
• Concerns:
• Not ambitious enough? Not enough impact for the cost?

Hydrogen Gas (“the perfect fuel”):

• Benefits:
• emits only water, no carbon dioxide
• Concerns:
• That used to day comes from reforming natural gas, which releases CO₂
• Very bulky to transport due to its low density; liquefaction consumes 40% of its energy
• Need totally new infrastructure, as current pipe system is not adequate
• Could be revolutionary, but technology won’t be available on large scales for a few decades

Alternative Energy Sources

The most mature and economically competitive alternative energy source is Wind

Wind:

• Benefits:
• Could provide 20% of US energy; President Clinton proclaimed the realizable goal of 5% by 2020
• Many viable locations where wind is always blowing strongly; best location in US is on the farms/plains of the Dakotas
• Easy and cheap to maintain
• Redundancy: can use excess power when energy not in high demand to store energy (e.g. via pumping compressed air into the ground) to be use in times of high demand
• Complaints:
• Only uses 28% of its capacity (100% = wind blowing full force continuously)
• Kills birds—cats kill more birds than wind farms, and climate change will likely kill more birds than wind farms as well
• Noise pollution—this is improving dramatically
• Ugly—uglier than a coal power plant?

Solar:

• Benefits:
• Hot water system:
• Place on the South-facing roof with a gas/electric booster to ensure hot water availability
• simplest, most cost-effective way to reduce emissions
• 1/9 of all CO₂ emissions come from heating water alone
• Photovoltaic cells:
• on roofs of homes and buildings
• 25-year guarantee and maintenance free
• In Japan, you are allowed to sell excess power from your solar cells to the grid for $50/month
• expected to be cost effective by as early as 2010
• Couples well with Wind power: when it’s not sunny it’s usually windy, and when it’s not windy it’s usually sunny
• Complaints:
• Price
• Some toxicity concerns

Nuclear:

• Benefits:
• Currently provides 18% of the world’s electricity
• Powers 80% of France’s electricity
• Zero CO₂ emissions
• Very efficient
• Concerns:
1. Safety: New nuclear technology is effectively fool-proof
2. Terrorism: Certainly proper plant protection would be needed
3. Nuclear Weapons Proliferation: How can we justify creating nuclear power plants while denying others on the grounds of avoiding nuclear proliferation?
4. Waste: This is a big problem, although recent technology is reducing the amount of waste dramatically

Ethanol:

• Benefits:
• Derived from corn--reduces foreign oil dependence
• Corn abundant in US
• Concerns:
• amount of fossil fuel required to grow the crop and convert it to ethanol implies that ethanol still emits as much, if not more, CO₂ than conventional gasoline

Bio-Diesel:

• Benefits:
• Uses old cooking oils and other organic material to produce energy
• Cheap, very efficient, relatively clean-burning
• One Culver’s restaurant in SE Wisconsin heats entire building by burning discarded cooking oils
• Concerns:
• Requires proper engine
• Public awareness

New Automotive Technology

Hybrid cars:

• Benefits
• Toyota Prius cuts fuel use and CO₂ emissions by 70%
• refuels every 600 miles
• Concerns
• Few know how to repair them
• A bit costly, but reasonable

Compressed air cars:

• Benefits:
• Very new technology
• top speed 75 mph
• Can travel 200 mi at 30 mph
• “Refueling” costs $2.50, takes 3 minutes with commercial compressor, 3.5 hours at home
• 3-seat MiniCAT = $10,000; 6-seat CitiCAT = $16,000
• Concerns:
• Technology not yet ready for open market
• Longer milage desirable

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