Environmental Impacts of Renewables Flashcards

A wind farm developer is conducting an environmental impact assessment for a site located along a major avian migratory route. Which of the following mitigation strategies has been shown to be effective in significantly reducing bird collision fatalities?

Answer: Painting one turbine blade black to increase its visibility.

Studies have demonstrated that painting one of a wind turbine's three blades black can reduce avian fatalities by over 70%. This technique is believed to work by reducing 'motion smear,' making the moving blades more visible to birds. Ultrasonic deterrents are generally more effective for bats, smaller blades often rotate faster increasing risk, and attracting birds to the base of turbines would likely increase collision risk.

When comparing the water consumption of utility-scale solar power technologies, what is the primary reason that Concentrating Solar Power (CSP) plants with wet cooling typically have a much higher water footprint than Photovoltaic (PV) plants?

Answer: CSP plants operate as thermal power plants and require large amounts of water for cooling steam in a turbine cycle.

Concentrating Solar Power (CSP) plants operate similarly to traditional thermal power plants by using heat to create steam that drives a turbine. Wet-cooled CSP plants require significant amounts of water for the cooling towers to condense this steam back into water. In contrast, Photovoltaic (PV) plants convert sunlight directly into electricity and do not have a steam cycle, so their water use is primarily limited to occasional panel cleaning.

While large-scale hydropower is often considered a low-carbon energy source, what is a significant, and sometimes overlooked, source of greenhouse gas emissions associated with the creation of large reservoirs, particularly in tropical regions?

Answer: The anaerobic decomposition of submerged vegetation and organic matter, releasing methane.

When a large reservoir is created, vast amounts of existing vegetation and organic soil are flooded. This organic material decomposes under anaerobic (low-oxygen) conditions at the bottom of the reservoir, a process that releases significant quantities of methane (CH4), a potent greenhouse gas. This effect is most pronounced in the initial years after flooding and in warmer, tropical climates where decomposition rates are higher.

A renewable energy professional is assessing the environmental concerns for a proposed geothermal power plant that will use an open-loop (flash steam) system. Which of the following airborne pollutants is a primary concern requiring specific abatement systems for this type of plant?

Answer: Hydrogen sulfide (H2S) released with the geothermal steam.

Geothermal reservoirs naturally contain dissolved gases, including hydrogen sulfide (H2S), which has a characteristic "rotten egg" smell and is toxic at high concentrations. In open-loop systems where steam is vented to the atmosphere, H2S is released and is a primary air quality concern. Modern geothermal plants employ H2S abatement systems to scrub or reinject this gas to meet environmental standards.

A project manager is developing a decommissioning plan for a 25-year-old utility-scale solar farm. Which of the following represents the most significant challenge in the end-of-life management of the photovoltaic (PV) panels?

Answer: The economic cost of recycling often exceeds the value of recovered materials and landfill fees.

While up to 95% of a solar panel's materials can be recycled, the primary barrier is economic. The cost to transport and process used panels through specialized recycling facilities is often higher than the cost of sending them to a landfill, especially where regulations are not strict. This economic disincentive, coupled with limited recycling infrastructure, is the biggest challenge facing the industry as the first wave of solar panels reaches end-of-life.

The concept of 'Indirect Land Use Change' (ILUC) is a major environmental concern for certain types of bioenergy. Which scenario best describes this phenomenon?

Answer: A farmer converts existing corn fields from food production to ethanol production, causing another farmer elsewhere to clear forest land to grow more corn for the food market.

Indirect Land Use Change (ILUC) refers to the unintended consequence of diverting existing cropland from food/feed production to biofuel production. This diversion increases demand for the displaced food/feed crop, raising prices and creating an economic incentive for farmers elsewhere in the world to convert non-agricultural land, such as forests or grasslands, into new cropland, thereby releasing stored carbon.