SET721-Engineering Sustainability

Questions

1. Population growth plays a key role in environmental sustainability. The United Nations estimates that the world population will reach 9.2 billion by 2050.

a. In 300 – 400 words, discuss the factors that influence population growth and how population growth effects/impacts environmental sustainability.

b. The population of china in the year 1999 was 1.2 billion and that of India was 986 million. Assuming a constant population growth rate of 2% per year, the population of India is predicted to equal the population of China in 20 years. At what constant rate must China’s population grow for the populations of the two countries to be equal in 2019, as predicted?

c. From current data, we know that the populations of the two countries are not equal as predicted 20 years ago, with the population of China at ~1.42 billion and that of India at ~1.37 billion. In two or three sentences, explain this discrepancy between the prediction and the reality.

2. Human activity has been linked to many of the currently observed changes to the environment, including global warming and climate change.

a. In 400 – 500 words, explain what greenhouse effect, global warming and climate change are, the connection between them and how they are linked to human activity.

b. With reference to Table 1 below, explain what is meant by global warming potential and discuss the factors that contribute to the differences in the values for different greenhouse gases. Why is there so much focus on CO2 even though it has a much lower global warming potential compared to other greenhouse gases?

c. Using the 100 years global warming potential figures from Table 1, calculate the number of tonnes of CO2 equivalent of 80 kg of N2O.

3. Energy in a particular country is derived from fossil fuels. Assume that this country requires 600 TW·hrs of electricity per year. The country’s government adopts a policy that in a specified time frame, 35% of its electricity supply will be from renewable sources.

(a) How many 1-MW wind turbines will be required to supply 35% of the country’s electricity needs? Assume a capacity factor of 100%.

(b) Assuming that an average wind turbine requires 1000 m2 of land for every kW of electricity produced by a wind turbine, how many square kilometres of land will need to be set aside to achieve this goal?

(c) Repeat (a) for a capacity factor of 20%.

(d) Repeat (b) for a capacity factor of 20%

(e) For a country with a total land area of 350,000 km2, is the result for

(d) practical?