Lecture 6 benefits of volcanoes

Question 1

How do volcanic eruptions help to improve climate models?

Answer 1

• radiative and dynamic aspects of model used for other climate related problems can be tested by these large episodic events.

Question 2

what reasons to study volcanoes and climate

Answer 2

• improve climate models
• allows to make seasonal and interannual forecasts following large volcanic eruptions.
• winter warming and summer cooling - summer indian monsoon failure will follow large high latitude eruptions.
• large volcanic eruptions may result in crop failure, famine and epidemic diseases
• it provides an analogy for geoengineering the climate (global warming mitigation) using stratospheric aerosols.

Question 3

What are the benefits of volcanic regions?

Answer 3

• mineral deposits
• tourism
• Fertile volcanic soils
• geothermal energy

Question 4

Why do soils have to do with volcanoes?

Answer 4

• developed from volcanic rocks, tend to be very fertile.
• e.g. productive vineyards m Mt Vesuvius, Italy.

Question 5

why do tourists come here?

Answer 5

Geo-tourism
Associated features: hot springs and geysers, spa resorts.
Brings significant revenue to many present day volcanic regions e.g. Iceland, Hawaii, Japan, New Zealand etc.

Question 6

What is geothermal energy?

Answer 6

Heat in Earth from decay of radioactive elements (e.g. U, Th, K).

Flow of internally generated heat across the Earth’s surface is fairly constant at 60 mWm-2 (milliwatts per square metre).

But in certain places (where there is a close association between hot springs and volcanoes) the flow of heat may be much greater, up to 300mWm-2.

Heat Flow in volcanic regions is sufficient to provide a viable source of energy
In geothermal areas such as Iceland and New Zealand ground waters may be heated to 200-300oC at depths of < 2km

Question 7

How does geothermal energy work?

Answer 7

Geothermal resources found in volcanic
regions with permeable rock strata
* Groundwater circulates to several km
depth and is heated by contact with hot
rock
* Hot water = less dense  rises to
surface  convection cells can develo

Question 8

What are the geothermal energy resources?

Answer 8

Globally, insignificant: 0.3% of annual
energy usage
* Iceland: 65 %
* Resources = hot water and steam (
electricity)

Question 9

what are the types of geothermal power plants?

Answer 9

Dry steam
drawing stream from underground and piping it from wells to power plant into a generator or turbine.

Flash steam
- most common type
water temps higher than 182 degrees Celsius.
- hot water flows up and boils off due to increased pressure.
- steam separated from water and used power turbine/ generator
- leftover water and condensed steam injected back into reservoir.

Binary cycle
- low temp water 107-182 degrees
- heat exchange to boil working fluid
- vaporized working fluid used to power turbine
- water re-injected into reservoir for re-heating
- water and working fluid kept separated during whole process.

Question 10

What power do they rely on in iceland?

Answer 10

• geothermal
  Reykjavik is heated almost entirely from hot water piped from underground.
• they use it for heater green houses - producing large amounts of tomatoes and various tropical fruits all year round.

Question 11

give an examples of CO2 mineralisation of basaltic rocks

Answer 11

basalt + co2 = calcite

Question 12

examples of carbon capture in geothermal systems

Answer 12

carbon upscaling

Question 13

examples of carbon fix

Answer 13

carbon upscaling
carbon capture

Question 14

What is the link of volcanic activities and mineral deposits?

Answer 14

Think of the arc system

Question 15

where do we find a high geothermal heat flux on earth and how is it related to volcanic activities?

Answer 15

constructive and destructive plate margins.