Exercises: Energy and mineral resources

Classify these energy resources into renewable and nonrenewable: coal, solar energy, natural gas, wind energy, uranium, and hydroelectric energy.

The diagram shows an anticline petroleum trap, with three numbered geological elements (1–3) and fluids separated by density. Name the three elements (source rock, reservoir rock and cap rock), explain why oil and gas are trapped in this position, and summarize how petroleum is formed.

What is biomass as an energy resource, and why is it only considered renewable if managed sustainably?

What is a fossil fuel and what are its three main forms? What do their origin and their atmospheric impact have in common?

Which physical process does a nuclear power plant harness and how does it differ from coal combustion in terms of atmospheric emissions and waste generated?

What is the difference between primary energy, such as coal, uranium or the sun, and final energy, such as electricity or gas? Why are there losses between the two?

What is the calorific value of a fuel and why does anthracite have a higher one than peat? Relate it to the rank of coalification.

What is a pumped-storage hydroelectric plant and which storage function does it fulfill in an electricity system with a lot of solar and wind energy?

Coal originates from ancient buried and transformed forests. Order the series of increasing rank: bituminous coal, peat, anthracite, and lignite, and explain how carbon content and moisture vary along the series.

A hydroelectric power plant and a wind farm are renewable facilities, but not harmless. Compare their environmental impacts (land, wildlife, landscape) and their ability to respond to electricity demand.

Surface (strip) coal mining leaves large pits and spoil piles. Describe its impact on landforms, bodies of water, and soil, and explain what a mine reclamation plan should include.

Oil forms from buried organic matter. Explain the role of kerogen and of the "oil window" (the temperature interval of formation), and what happens if burial exceeds those temperatures.

Compare natural gas and oil: common origin, state and composition, transport (gas pipelines and liquefied natural gas versus oil pipelines) and main uses.

Hydraulic fracturing (fracking) extracts gas from shale rocks. Explain what the technique consists of and analyze two advantages (new resources, energy independence) and two risks (induced seismicity, water pollution).

Which energies do tidal and wave power plants harness and how do they differ? Assess their current development compared with solar and wind energy.

What is the capacity factor of a renewable source? Explain why the intermittency of solar and wind energy requires backup systems (pumped storage, batteries, interconnections) and how they are managed.

Imagine that a report published in the press states: "Given that Spain already generates more than 50% of its electricity with renewable sources (wind and solar), its foreign energy dependence has been drastically reduced and lacking sedimentary basins rich in hydrocarbons has ceased to condition its economy."

1. a) Technically refute this statement by distinguishing between the electricity generation mix and the primary energy mix in Spain, justifying why peninsular geology continues to determine strategic vulnerability and the foreign energy bill.
2. b) Design two sectoral proposals to decouple heavy transport and thermal industry from imported fossil fuels, evaluating the geological or critical materials bottlenecks associated with each.

A company is considering two sites in Spain to install a binary cycle or steam geothermal power plant that requires at least 150 °C at less than 2 km depth to be economically viable:

• Borehole A (Tertiary sedimentary basin in stable continental crust): average surface temperature of 14 °C and average geothermal gradient of 3.0 °C per 100 m.

• Borehole B (volcanic terrain in the Canary Islands on a shallow thermal anomaly): average surface temperature of 20 °C and local geothermal gradient of 8.5 °C per 100 m.

1. a) Calculate the exact depth at which 150 °C is reached in each borehole and justify the technical and economic feasibility of drilling in both cases.
2. b) Describe the four indispensable elements of a high-enthalpy geothermal reservoir (heat source, permeable aquifer, cap rock, and recharge mechanism) and predict what hydrogeological or induced seismicity problems could arise if the reservoir of the viable borehole is overexploited without fluid reinjection.

A wind farm with 20 wind turbines is planned on a limestone mountain ridge at an altitude of 1300 m, with average winds of 7.5 m/s. The crest features karst sinkholes (dolines) and limestone pavements (karren) that feed the water supply springs of two valleys, and constitutes the daily flight corridor for a colony of griffon vultures (Gyps fulvus) and Egyptian vultures (Neophron percnopterus).

1. a) Analyze the specific geological and hydrogeological impacts resulting from the opening of access tracks and the excavation of footings in a karst massif, predicting how they may alter infiltration and water turbidity in the springs.
2. b) Design a tiered plan of preventive and corrective measures to reconcile the facility with conservation: determine what technical conditions you would require for turbine placement, what automated bird detection and shutdown systems you would implement, and how you would solve the electrical evacuation to minimize landscape fragmentation.

An average electric vehicle requires multiplying by six the mass of critical minerals (lithium, cobalt, nickel, manganese, and rare earths) compared to an internal combustion vehicle. 70% of cobalt comes from the Democratic Republic of the Congo and over 65% of lithium and rare earth refining is geographically concentrated in China. In Spain, hard-rock lithium mining projects (Cáceres) and rare earth projects (Ciudad Real) face strong social and environmental opposition.\n\na) Analyze the territorial and environmental inconsistency involved in adopting massive electrification policies while externalizing the ecological and social footprint of extractive mining to countries with lax environmental or labor frameworks.\nb) Design a set of three strategic measures (technical and regulatory) for the European Union to reduce supply vulnerability for these metals without deteriorating local ecosystems, critically assessing to what extent closed-loop recycling can replace primary mining over the next 15 years considering the growth of the battery fleet.