Energy Context

Question 1

4 reasons for taking action to reduce fuel consumption? (other than pollution)

Answer 1

1. Poor air quality from various gases and emissions
2. diminishing FF’s causing price rise
3. security of supply - imports
4. maintenance of sustainable growth

Question 2

What are the three main categories of energy supply system?

Answer 2

1. Fossil fuels
2. Nuclear
3. renewable

Question 3

Why is the harnessing of renewable energy difficult?

Answer 3

1. There are many policy, technology and socio-economic barriers.
2. The practical resource is not vast relative to total energy demand.
3. Matching a large portion of demand will require the industrialisation of the environment on a large scale
4. High capture levels require: increased transmission network capacity; active distribution network management; and energy storage and/or standby capacity.

Question 4

Why is it hard to take action to reduce energy demand?

Answer 4

significant reduction in demand will require lifestyle changes that are unlikely to be acceptable to citizens (e.g. not flying or buying ‘stuff’)

Question 5

List 5 energy efficiency measures that might be applied to the built environment.

Answer 5

1. turn down the heating system thermostat;
2. replace gas boilers with electric heat pumps;
3. upgrade the fabric (e.g. insulate, apply phase change material etc.);
4. draught proof and recover heat from ventilation air;
5. introduce passive solar features

Question 6

What is embedded generation?

Answer 6

A scheme in which small scale generators (such as combined heat and power plant, ducted wind turbines, photovoltaic components etc.) are deployed locally and used alongside conventional energy supply connections (gas and electricity) to match the energy demands of a single building or community

Question 7

Why do we need to model energy systems?

Answer 7

To support design decisions relating to:

1. align with legislative requirements;
2. make sure the levels of comfort will be right;
3. meet indoor air quality standards;
4. to embody high levels of new and renewable energy technologies;
5. to incorporate innovative energy efficiency and demand side management solutions; and
6. to lessen environmental impact.

Question 8

Why are energy systems difficult to model?

Answer 8

Because energy systems are complex due to:

1. dynamic effects (different flow-paths vary at different rates over time)
2. systemic effects (all flow-paths are connected and influence each other)
3. non-linear effects (the defining parameters (e.g. material conductivity, heat transfer coefficients etc.) depend on the variables of state

Question 9

What are the 2 main dynamic modelling methods?

Answer 9

1. Response function method - configured in t or f domain.
2. Numerical methods - conservation equations are established for each of many small finite volumes that represent the discretised problem and then solved instantaneously to give the variables of state over time.