2016 - Past Paper Questions Flashcards
Explain the following terms: Low Solids High Solids Residence Time Single - Stage Multi - Stage
Low solids:
Low solid digestion is where the feedstock is around 15% solid material [1]
High solids:
High solid digestion is where the feedstock is around 55% solid material. [1]
Residence Time:
The time taken for the full degradation of the material in an anaerobic digestion system. [1]
Single Stage:
The biological reactions occur in one holding tank and the biogas comes from this tank. [1]
Multistage:
Hydrolysis, acetogenesis and acidogenesis occurs in one tank whilst the methanogenesis which produces the biogas occurs in a separate tank. [1]
Outline how anaerobic digestion can be used to provide heat and power (CHP)
Biogas from an AD plant can be burnt in a CHP plant to generate power (electricity) and heat [1];
Instead of losing the heat, as in traditional power plants, it is diverted into local heating systems. [1]
Name three types of waste product which can be composted in a domestic situation
Any three from: • Lawn clippings. [1] • Shredded stalks. [1] • Vegetable peelings. [1] • Hedge clippings. [1] • Cut flowers. [1] • Tea bags. [1] • Leaves. [1] • Eggshells. [1]
Explain briefly why composting is unsuitable for treating any form of catering waste
Cooked food must never be used in composting because it will attract vermin
Describe one efficiency measure which can be implemented on the window and explain why this measure would improve the energy efficiency
Any one measure and explanation from:
• Sealing around the edges of the window [1]; this will improve airtightness and reduce heat loss caused by draughts. [1];
• Installing double (or triple) glazed windows [1]; These will have improved U-values and will reduce heat loss through window. [1];
State one economic and one environmental benefit of energy conservation to be gained by putting in cavity insulation
Economic benefits: Any one from: • reduced heating costs. • improving the value of your home. • grant assistance available for the work.
Environmental benefits: Any one from: • reduced carbon emissions. • increased levels of home comfort. • reducing likelihood of condensation and mildew.
Explain how a tidal barrage generates energy from the tides
A barrage is built across an estuary with gates and turbines built into the wall of the dam [1];
As the tide flows in the gates are open and the turbines are operated producing electricity [1];
At high tide the gates are closed trapping the water inside [1];
When water level outside has fallen sufficiently(e.g. 5 m) the gates are opened [1];
The released water turns the turbines again producing electricity. [1]
Outline two advantages of a Tidal stream generator over a tidal barrage installation
Any two advantages from:
• They are cheaper to construct. [1]
• They are smaller and have less environmental impact. [1]
• The turbine blades turn slowly and have less effect on sea life. [1]
Give one Example of a ‘Geo - Engineering’ technique and explain how it can be applied
- Cloud seeding [1] where clouds are injected with crystals to produce ‘rain on demand’. [1]
- Space reflectors [1] which block a proportion of the sun’s rays from entering the earth’s atmosphere thereby reducing global warming. [1]
- Afforestation [1] whereby global scale planting of trees absorbs CO2 from the atmosphere. [1]
- Biochar [1], the process of ‘charring’ biomass so that the carbon it contains is locked up in the soil. [1]
Describe the operation of Bio-Photovoltaic devices
Bio-Photovoltaic (BPV) devices generate electricity from light energy [1] by exploiting the photosynthesis of living organisms such as moss, algae, cyanobacteria and vascular plants. [1]
Describe the process of Bioremediation
Adding micro-organisms to soil [1] to remove contaminants.
Discuss the economic and environmental benefits of using bioremediation techniques compared to traditional treatment methods
Bioremediation:
• Bioremediation can be carried out under atmospheric conditions.
• Bioremediation can be carried out in situ so soil is not removed from the site.
• The contaminants are reduced to (almost) zero.
• The by-products are non-toxic so water and air pollution is minimised.
• Bioremediation uses bacteria that occur naturally in the soil so the ecosystem is maintained.
• Bioremediation is economical because it does not require large energy inputs.
Traditional treatment:
• Traditional treatment is expensive because of the high energy costs (heating).
• Greenhouse gases such as carbon dioxide are produced.
• Soil may need to be treated ex situ/off site which requires heavy machinery.
• Traditional treatment can produce toxic by-products which require further treatment.
• Soil may need to be disposed of after treatment which leads to increased landfill.
Outline the role of genetic engineering in modifying micro organisms for bioremediation
Any two points from below:
Micro-organisms can be genetically engineered to:
• decontaminate a site more rapidly than unmodified micro-organisms;
• tolerate harsher conditions;
• remove toxic materials (such as heavy metals).
Identify two issues of concern arising from the use of genetic engineering of micro organisms for bioremediation
Any two from:
• Genetically engineered micro-organisms may wipe out existing bacteria.
• They may affect the existing soil ecology with unknown consequences.
• They may not behave the same way in the field as they do under laboratory conditions.
Describe two difficulties with locating a new landfill site
Any two points from:
• Planning permission is required which can delay the landfill becoming operational by several years. [1]
• A permit is required for operation which requires that full surveys have been carried out. This process is time consuming and adds to the up-front costs for the operator. [1]
• There may be objections from local residents due to noise/odour issues. This will delay planning permission being granted and subsequent award of a permit. [1]
• Suitable transport links are required so that waste can be brought to the site in heavy goods vehicles. [1]
Describe two difficulties with developing a new landfill site
Development:
Any two points from:
• Once a permit/licence has been granted it takes a further 18 months from beginning of construction to operation adding to up-front investment costs. [1]
• The site must be geologically suitable so that the polluting leachates from the site cannot affect the surrounding land and water. [1]
• A detailed site survey is required prior to operation to ensure that the landfill site will not cause movement of the surrounding land. [1]
• An environmental assessment is required to confirm that the effect of the landfill site on the local environment is minimal. [1]
• The landfill must include leachate and landfill gas treatment measures to minimise water and air pollution. [1]
• Leak detection is required as flammable methane gas can be released. Methane gas is a greenhouse gas. [1]
Name one major waste type
Any one from:
Municipal waste/Commercial and industrial waste/Construction, demolition and excavation wastes/Hazardous waste/Agricultural waste.
Discuss the main characteristics that you would propose for this urban development that would link sustainability, zero carbon concepts and the role of technology. Specific reference to the following:
- Reduced energy use for heating/cooling and microgeneration (smart grid technology)
- Integrated and flexible transport facilities/versatile buildings
- Waste management/Land use
- Dealing with water shortages/sustainable urban drainage
- Green Spaces - environmental benefits
Energy use for heating/cooling and microgeneration (including the use of smart grid technology):
• reduced energy use for heating and cooling; passive ventilation; natural cooling; better insulation, glazing, orientation.
• microgeneration of electricity (using solar power and micro wind linked via smart grid) and heat using heat pumps, biomass etc.
Integrated and flexible transport facilities/versatile buildings:
• public transport, cycling, walking, park and ride, etc.
• lower cost and more comfortable and versatile buildings/design for re-use etc.
Waste management/land use (brownfield sites):
• planned waste management systems that deal with the waste source (e.g. waste management strategies; recycling; composting; biomass etc.).
• the reuse of brownfield sites (e.g. building on previously developed land)
Dealing with water shortages/sustainable urban drainage.
• systems to deal with water shortage (e.g. managing water usage; water metering; low water usage sanitary ware; rainwater harvesting; greywater recycling; etc.).
• sustainable urban drainage schemes (e.g. flood mitigation measures; SUDS).
Green spaces – environmental benefits:
• using green spaces to moderate the urban heat island (e.g. using trees to create shade/ local microclimate/ heat sinks).
• using green spaces that work for people and wildlife, for example food production in urban areas.
