Pros and Cons of Renewable/alternative sources of energy

ProsCons

Tidal Energy

Renewable. Requires no fuel. Emission-free Reliable, a plant can last 100 years High efficiency Predictable output Could potentially provide a storm surge barrier. Environmental impacts are local, not global Expensive to build Very location specific (only 20 sites identified with high potential) Non-continuous, storage or grid-backup required Locations are often remote Barrages may restrict access to open water Can change tidal level of surrounding area Impact on fish, marine mammals and birds Disrupts regular tidal cycles Decreases salinity in tidal basins Mud flats (where many birds feed) adversely impacted Captures dirt, waste and pollution near the coast Reduces kinetic energy in the ocean

Wind energy

Clean energy, no fuel to drill, frack, mine, transport or burn Renewable and sustainable Costs are relatively low and continue to decrease Abundant domestic supply (16X current electric demand!) The power is essentially free once the infrastructure is paid for. Low life cycle carbon footprint. Breakeven in eight months. Can be used almost anywhere. As mentioned earlier, the wind is inconsistent, unsteady and unpredictable Wind power is not cheap and like many energy sources, rely on government subsidies to remain competitive. Wind farms are generally located in rural areas that might be otherwise picturesque. They are considered by some people to be an eyesore. Some people complain of noise from the turbines. Wildlife impact. Not only birds, but bats have experienced fatalities. Localized impact on night-time temperatures and weather

Biofuel production by algae

Bio-based fuel with essentially carbon neutral combustion Drop in replacement for petroleum-based liquid fuels Inherently renewable Absorbs carbon dioxide as it grows Both waste CO2 and wastewater can be used as nutrients Higher energy per-acre than other bio-fuels Can be grown on land unsuitable for other types of agriculture Scalable: Study found that 17percent of U.S. oil imports could be met with algae Investments are being made Production is presently scaling up (Navy buying 100,000 gallons this year) Research has been underway for 50 years Need to be grown under controlled temperature conditions Requires a considerable amount of land and water Cold flow issues with algal biofuel Some researchers using genetic engineering to develop optimal algae strains Requires phosphorus as a fertilizer which is becoming scarce Fertilizer production is carbon dependent Relatively high upfront capital costs Not clear yet what the ultimate cost per gallon will be. Presently too high.

Solar power from photovoltaic cells

Clean energy. No combustion. No greenhouse gas emission from use. Inexhaustible and abundant fuel supply Available nearly everywhere Well suited for distribution generation Technology exists today and is rapidly improving Generates electricity directly from sunlight No moving parts required Power generation is silent. No noise or pollution. Little or no transmission required Matches up well with air-conditioning need Require minimal maintenance Grants and incentives are sometimes available Excess heat can be used for co-generation Intermittent source. Not available at night or under clouds. Relatively high cost, especially with storage Requires inverter to produce AC current Requires storage or grid connection for continuous round-the-clock use Less available for heating demand (time of day and season) Exotic materials required in many thin-film systems Requires a relatively large amount of open space Relatively low efficiency (around 17-40 percent) Fragile materials Possible aesthetic issues Technology risk: a much better system might come out next year