The Engineering Challenges of Renewable Energy: Crash Course Engineering #30

Summary

This script discusses the environmental and sustainability issues of non-renewable energy sources and highlights the importance of renewable alternatives. It explores how hydropower, wind, geothermal, and solar power are harnessed, the challenges they face, and the innovations engineers are developing to overcome these obstacles and transition to cleaner energy solutions.

Takeaways

• 🔥 Engineering has significantly contributed to global development but relies heavily on non-renewable fuels.
• ⏳ Non-renewable resources like oil and natural gas are predicted to deplete within half a century.
• 🌍 Burning fossil fuels contributes to 87% of human-caused carbon dioxide emissions over the last 50 years.
• 💧 Hydropower converts the kinetic energy of flowing water into electricity but struggles with demand control.
• 🌪️ Wind power uses turbines to harness energy from air but faces challenges with inconsistent wind strength.
• 🌡️ Geothermal power uses underground heat to generate steam for electricity but is limited by geographical availability.
• ☀️ Solar power has the potential to be abundant and accessible but currently faces efficiency and storage challenges.
• 💹 The cost of solar power production is currently higher than that of fossil fuels due to inefficiencies and production costs.
• 🔄 Engineers are exploring new materials and technologies to improve the efficiency and economic viability of solar panels.
• 🌐 Renewable energy sources are critical for meeting future energy demands and reducing environmental impact.

Q & A

What is the primary concern with relying on non-renewable fuels for powering engineering developments?

The main concern is that non-renewable fuels, such as oil and natural gas, are being depleted much faster than they can be naturally replenished, and their use has a detrimental impact on the environment, contributing significantly to harmful carbon dioxide emissions.

How much of the power used in the United States in 2017 was supplied by fossil fuels?

In 2017, 80% of the power used in the United States was supplied by fossil fuels.

What is the process of nuclear fission and why is it less desirable despite producing less CO2?

Nuclear fission is the process of splitting atoms to release energy, which produces far less CO2 compared to fossil fuels. However, it is less desirable because it generates radioactive waste and relies on non-renewable fuel sources like uranium and plutonium.

How do renewable energy sources like wind and hydropower work in comparison to traditional heat engines?

Renewable energy sources like wind and hydropower operate using turbines, where wind turbines use air and hydropower uses flowing water to turn the blades of a generator. Unlike traditional heat engines that rely on heating a working fluid, these renewable sources harness kinetic energy from natural processes.

What is the challenge with hydropower when it comes to controlling energy generation to meet demand?

The challenge with hydropower is that the generation of energy cannot be easily controlled to meet demand because it depends on natural factors like river flow, which is influenced by rainfall and temperature, both of which cannot be controlled.

How does a hydroelectric dam overcome the challenge of controlling energy generation in hydropower?

A hydroelectric dam overcomes the challenge by creating a reservoir of water that can be controlled through an intake valve, allowing for the management of water flow through the turbines to meet the changing demands of the electrical grid.

What are the environmental concerns associated with building a hydroelectric dam?

Building a hydroelectric dam can have devastating consequences for the local ecology due to the sudden environmental changes caused by flooding an area and preventing the natural flow of water downstream. There is also the risk of the dam breaking if it was not built properly.

What is the role of location in the effectiveness of wind power and geothermal power?

Location plays a significant role in the effectiveness of wind power and geothermal power. Wind power is more effective in sparsely populated, open plains where wind is more consistent, while geothermal power is feasible in areas near the Earth’s tectonic plate boundaries where underground heat sources are accessible.

How do solar panels convert sunlight into electricity and what is the challenge with their efficiency?

Solar panels, or photovoltaic cells, convert sunlight into electricity by using two different semiconducting pieces to create an electrical field that biases the movement of free electrons, encouraging an electrical current to flow. The challenge is that solar cells are not very efficient, with the best cells converting about 40% of absorbed energy into electricity, but they are expensive to produce. On average, industrial PV cells are about 17% efficient.

What are some of the methods engineers are considering to improve the storage of solar power?

Engineers are considering methods such as using solar power to drive hydrogen fuel production, which can be stored and burned later with no carbon dioxide emissions, and exploring new materials and structures, like nanocrystals, to increase the efficiency of solar panels.

What is the significance of the efficiency of solar panels in making them economically competitive with current power sources?

The efficiency of solar panels is significant because higher efficiency would reduce the cost of solar power production, making it more economically competitive with current power sources. This could lead to increased adoption of solar power worldwide.

What are some of the environmental challenges associated with manufacturing solar panels?

Manufacturing solar panels involves processing quartz to produce high-quality silicon, which is an energy-intensive process that offsets some of the total energy production of solar panels. Additionally, this process can produce toxic byproducts like tetrachloride, which can harm the environment.

Outlines

00:00

🔥 Fossil Fuels and the Need for Renewable Energy

This paragraph discusses the significant contributions of engineering to global development, such as improving sanitation and creating infrastructure. However, it also highlights the reliance on non-renewable fuels like oil and natural gas, which are not only harmful to the environment but also finite. The paragraph emphasizes the urgent need to find alternative energy sources due to the alarming rate of fossil fuel consumption and their detrimental impact on climate change. It contrasts the current energy production methods, which are largely based on heat engines, with the potential of renewable energy sources that are both sustainable and environmentally friendly.

05:06

💧 Harnessing Renewable Energy: Hydropower and Wind Power

The second paragraph delves into the challenges and benefits of harnessing renewable energy sources like hydropower and wind power. It explains how hydropower is generated through the kinetic energy of flowing water, either through run-of-river systems or dams, and the difficulties associated with controlling energy production to meet demand. The paragraph also addresses the environmental impact of large-scale hydroelectric projects. Wind power is discussed in terms of its generation through turbines and the engineering challenges involved in designing efficient blades and dealing with the unpredictable nature of wind. The limitations of these renewable sources, such as the need for large installations and the issues of energy storage and transmission, are also highlighted.

10:10

🌞 Solar Power and the Future of Renewable Energy

The final paragraph focuses on solar energy as a promising renewable energy source. It describes the technology behind photovoltaic cells and solar panels, which convert sunlight directly into electricity without the need for turbines. The challenges of solar energy, including the inefficiency of current solar cells, the high costs of production, and the need for efficient energy storage solutions, are discussed. The paragraph also touches on the environmental impact of solar panel manufacturing and the potential for future advancements in solar technology, such as new storage methods and materials that could increase efficiency. The importance of engineers in overcoming these challenges and the potential for solar energy to become a more economical and widely adopted power source is emphasized.

Keywords

💡Non-renewable fuels

Non-renewable fuels are energy sources that cannot be replenished within a human time scale, such as oil, coal, and natural gas. These fuels are formed over millions of years and are being consumed at a much faster rate than they are naturally produced. In the video, it is mentioned that reliance on non-renewable fuels has powered significant technological advancements but has also led to environmental concerns due to their finite nature and the pollution they cause.

💡Fossil fuels

Fossil fuels are a type of non-renewable fuel formed from the remains of ancient plants and animals. They include coal, oil, and natural gas. The video discusses how the burning of fossil fuels has contributed to 87% of the harmful carbon dioxide emissions in the last 50 years, highlighting their significant impact on climate change.

💡Renewable energy sources

Renewable energy sources are those that can be replenished naturally at a rate equal to or faster than they are consumed. Examples include wind, solar, hydropower, and geothermal energy. The video emphasizes the importance of renewable energy as a sustainable alternative to non-renewables, given their minimal environmental impact and the fact they won't run out.

💡Hydropower

Hydropower is a form of renewable energy that uses the power of moving water to generate electricity. The video explains how hydropower works by diverting a portion of a river's flow to turn turbines, which then generate electricity. It also discusses the challenges of controlling energy generation to meet demand and the environmental impact of building dams.

💡Wind power

Wind power is another renewable energy source that harnesses the kinetic energy of wind to turn turbines and generate electricity. The video describes the engineering challenges of designing efficient turbine blades and the unpredictability of wind strength, which can affect the reliability of power generation.

💡Geothermal power

Geothermal power is a renewable energy source that uses the Earth's internal heat to generate electricity. The video mentions that geothermal power plants can be set up by drilling into underground hot rocks and using the heat to create steam that drives turbines. It also points out the high costs and geographical limitations associated with setting up geothermal plants.

💡Solar power

Solar power is a form of renewable energy that converts sunlight directly into electricity using photovoltaic (PV) cells, commonly known as solar panels. The video highlights the abundance of solar energy and the challenges of harnessing it efficiently, including the inefficiency of current solar cells and the need for energy storage solutions.

💡Photovoltaic cells

Photovoltaic cells, or PV cells, are the technology used in solar panels to convert sunlight into electricity. The video explains how PV cells work by using semiconductors to create an electric field that biases the movement of electrons when energy is received from sunlight, thus generating an electrical current.

💡Energy storage

Energy storage refers to the methods and technologies used to store energy for use when it is needed, such as during periods of high demand or when the energy source is not available. The video discusses the importance of energy storage for renewable energy sources, particularly solar and wind, to balance supply and demand.

💡Nanocrystals

Nanocrystals are tiny structures on a molecular level that are being researched for their potential to increase the efficiency of solar panels. The video mentions that nanocrystals could help capture more energy from sunlight, converting it into electricity instead of losing it as heat, which could make solar power more economically competitive.

💡Grand Challenges

The Grand Challenges are a set of problems identified by the National Academy of Engineering in the US that engineers in the 21st century need to solve. The video states that making solar energy more economical is one of these challenges, indicating the importance of renewable energy in the future of engineering.

Highlights

Engineering has transformed work, sanitation, and infrastructure but relies on non-renewable fuels.

Non-renewable fuels like oil and natural gas may be depleted in half a century.

87% of human-emitted carbon dioxide in the last 50 years comes from burning fossil fuels.

In 2017, 80% of US power was supplied by fossil fuels, highlighting their dominance.

Nuclear fission produces less CO2 but generates radioactive waste and relies on non-renewable fuels.

Renewable energy sources like wind, solar, hydro, and geothermal are replenished as fast as used.

Hydropower converts kinetic energy from flowing water into electricity.

Hydropower plants struggle to control energy generation to meet demand due to uncontrollable river flow.

Hydroelectric dams solve the problem of uncontrollable generation by controlling water flow.

Wind power uses air to rotate turbine blades, but its generation is uncontrollable.

Geothermal power uses underground volcanic rocks as a heat source for steam generation.

Solar energy is abundant, but harnessing it efficiently is challenging.

Solar panels use photovoltaic cells to convert sunlight into electricity without turbines.

Solar cells' efficiency is a significant challenge, with the best cells converting up to 40% of absorbed energy.

Energy storage is a critical issue for solar power, as direct sunlight storage is not possible.

Solar panels can be deployed locally, reducing the need for long-distance power transmission.

The production of solar panels is energy-intensive and can produce toxic byproducts.

Engineers are working on new materials and structures like nanocrystals to increase solar cell efficiency.

Making solar energy more economical is identified as a Grand Challenge for 21st-century engineers.

Transcripts

Engineering has given a lot to the world.

It’s transformed the nature of work, improved sanitation and helped create vital infrastructure.

The bad news is that to power the tools and processes behind those developments, we’ve relied on non-renewable fuels –

the kind that get produced at a much slower rate than we use them.

As the name implies, non-renewables won’t be around forever.

Resources like oil and natural gas might be gone in just half a century.

And using them has been, frankly, pretty terrible for the environment.

87% of the harmful carbon dioxide emitted by humans in the last 50 years has come from burning fuels such as coal, oil, and natural gas, known collectively as fossil fuels.

It’s been terrible for the atmosphere and oceans, and is changing our climate in dangerous ways.

Whether we like it or not, we’re gonna have to find new ways to power our world.

[Theme Music]

Despite their terrible effects on the environment and limited supply, for now, non-renewables do a really good job of meeting our energy needs.

In 2017, 80% of the power used in the United States was supplied using fossil fuels.

And the need for energy doesn’t appear to be shrinking any time soon.

Another 9% was delivered from nuclear fission, the process of splitting atoms, which releases far less CO2.

Unfortunately, fission produces radioactive waste and also relies on non-renewable fuel sources such as uranium and plutonium.

All of these methods operate on broadly the same principle, essentially operating as a heat engine.

A working fluid, often water, is heated by the fuel to expand and do work, turning the blades of a turbine.

The turbine is connected to an electrical generator that converts the rotational motion of the blades into electrical power, which is then fed into the grid.

So what about that remaining 11% of power?

That came from renewable energy sources – the kind that are generated about as fast as we use them.

Some of the major renewable energy sources come from processes that are naturally occurring on Earth:

wind power; solar power; hydropower – which is based on flowing water; and geothermal power, which uses the heat of the Earth deep underground.

None of these sources are things we’ll run out of – we have a good few billion years left of sunlight, for example.

And what’s more, renewable energy tends to release fewer harmful byproducts, like carbon dioxide, into the environment.

Take hydropower, for example, which converts the kinetic energy from the motion of running water into electrical power.

In a fast flowing river, a run-of-river power plant diverts part of the river’s flow, sometimes through a tunnel, to turn the turbinesof a generator.

That works well in some places, but the problem with this approach is that it’s tricky to control the generation of energy to meet demand.

You don’t want to put lots of power into the grid when it won’t get used, and you want to be able to ramp up the supply when the demand suddenly spikes.

Like during the halftime break when the English football team – that’s soccer to you Americans – played Colombia in the 2018 World Cup.

A huge number of people in the UK opened their refrigerators to grab a drink or a snack, causing the compressors inside them to turn on.

Then there were the people who’d already had a bunch of drinks.

All those people simultaneously flushing their toilets during the break created an increased demand for power on the local pumping stations that maintain pressure in the water system.

The total increase in demand was measured to be 1200 megawatts.

That’s an extra demand for power equivalent to several power plants!

With fossil fuels, you can control the amount of fuel being burned, and therefore the amount of power being produced.

Run-of-river power plants struggle with this because the amount of power they generate depends on the flow of the river,

which in turn depends on things like the rainfall during the time period and even the temperature – both things we can’t control.

To get around this, the more common form of hydropower is a hydroelectric dam.

In this case, you can install a dam that floods an area and creates a huge reservoir of water.

The water then falls through the generator’s turbines at the bottom of the dam, which turn the water’s kinetic energy into power.

If you install an intake valve that opens or shuts to control the water flow through it,

you can even manage the production of energy to meet the changing demands of the electrical grid.

Unfortunately, flooding an area with water isn’t consequence-free.

Changing the environment so suddenly and preventing the natural flow of water downstream can have devastating consequences for the local ecology.

There’s also the risk of the dam breaking if it was built improperly.

Despite those challenges, hydropower has been enormously helpful.

In recent years, it’s produced as much as 16% of the world’s energy and up to 70% of all the world’s renewable energy.

The other renewable energy source that works very similarly to hydropower is wind power, which also uses turbines.

The main difference is that the fluid doing work on the wind turbines is air instead of water.

One of the biggest engineering challenges here is designing the turbine blades to efficiently extract energy from that air.

As we saw with fluid mechanics, predicting the flow of a fluid around an object can get seriously tricky!

Blades have to be engineered to withstand the stress they’re subjected to while also allowing the wind to efficiently rotate them to power the generator.

It’s as complicated as designing an airplane wing.

Once again, you run into the problem of demand: you can’t control the strength of the wind to increase or decrease power generation as you need it.

Even if that were possible, you’d still have to transport it from the sparsely populated, open plains where the wind blows more easily,

to dense urban centers with low amounts of wind but high demand for power.

Transporting that power becomes even trickier over long distances because you lose some energy as the electricity travels through the wires.

For that reason and others, engineering considerations often play a big role in deciding where wind farms (as a collection of turbines is known) should be built.

So wind power has only generated 4% of the world’s total power supply in recent years.

Location also plays an important role in another renewable energy source: geothermal power.

Like conventional power plants, geothermal power relies on steam as the working fluid on the turbines connected to the generator.

But in this case, you don’t need fuel to generate the steam.

You can drill into underground deposits of hot, volcanic rocks, normally near the Earth’s tectonic plate boundaries, to use them as a heat source for a power plant.

Then, all you need is to pump water to that location and create another channel for steam to rise through to do work on the turbines.

The biggest problem comes with setting up a geothermal power plant in the first place.

It can be expensive to drill and explore for underground conditions that are exactly right,

and is only really possible in certain parts of the world, like Iceland and Italy.

But there’s one source of renewable energy that’s so abundant and easily accessible

you only have to step outside on a bright sunny day to see it: solar energy!

In fact, the amount of sunlight the Earth receives in just a single year

is twice the total amount of energy that will ever be extracted from fossil fuels and the uranium used in nuclear fission, combined.

The challenge is finding efficient ways to harness that energy, because turning sunlight into electricity isn’t simple.

The most promising technology we have is called the photovoltaic, or simply, PV cell.

Most people know them by the name given to many cells arranged together: solar panels!

Unlike everything else we’ve looked at, there’s no trace of a turbine here.

Instead, as we saw when looking at semiconductors,

solar panels use two different semiconducting pieces to set up an electrical field that biases the movement of free electrons inside the material in a particular direction.

In short, the materials encourage an electrical current to flow when they receive energy,

which then travels through the circuit delivering power to whatever’s connected to the PV cell.

That means solar panels can deliver power directly to the grid.

Between that and the abundance of sunlight, it seems like there shouldn’t be an energy shortage problem at all.

But, as we’ve seen for the other energy sources, costs, fluctuating demand, location, and transmission all factor in here.

For starters, solar cells aren’t all that efficient.

The very best solar cells can convert 40% of the energy they absorb into electrical power,

but they’re expensive to produce because of the high quality of silicon needed in manufacturing, among other reasons.

On average, industrial PV cells are about 17% efficient.

Once you factor in the cost of making the cells and energy storage, solar power ends up being anywhere between 3-6 times as expensive to produce as that from fossil fuels.

Increasing solar panels’ efficiency would bring this down dramatically.

Another big challenge with solar power is that, like with the hydroelectric dam, you need a way to store energy to control the production in line with power demand.

You won’t generate much solar power on a cloudy day, whereas you might have a surplus on sunny days.

But you can’t store sunlight directly!

Instead, engineers are working on ways to temporarily store that extra solar power.

These include solutions like batteries, or even pumping water up a column to later give up its energy as hydropower during periods of high demand.

Once again though, efficiency plays a big role in making both of these methods a suitable form of energy storage.

Despite the efficiency and storage problems, there is one major advantage to solar panels: they can be deployed pretty much anywhere.

Rather than having to transmit power across long distances, solar panels can simply be installed on smaller scales close to areas of demand –

even on the roof of an individual home.

But manufacturing the panels themselves brings its own set of issues.

One of the raw materials used to currently make solar panels is quartz, which has to be processed to produce the high quality silicon needed for making PV cells.

This itself is an energy intensive process, which offsets some of the total energy production of solar panels across their lifetime of usage.

Even worse, processing quartz can often produce toxic byproducts like tetrachloride, which can end up spilling into the environment and causing damage to soil.

That all sounds a little bleak, but the most difficult challenges in engineering are often the most important ones.

In fact, the National Academy of Engineering in the US has identified making solar energy more economical as one of the Grand Challenges that engineers in the 21st Century need to solve.

Future engineers have lots of ways to contribute towards making solar more feasible.

Currently, researchers are looking at new storage systems, such as using solar power to drive hydrogen fuel production,

which can be burned later on with no carbon dioxide emissions.

More on that next time.

Engineers are also introducing new materials into the production of solar panels, and improving the ways in which PV cells themselves are linked and arranged on the panels.

There are even experimental methods being developed that use new structures on a molecular level, called nanocrystals.

These increase the amount of energy given to the electrons in the material when ligh is absorbed instead of losing the energy as heat.

That could drive the efficiency high enough to make it economically competitive with current power sources and increase the adoption of solar worldwide.

So there are lots of challenges ahead in bringing renewable energy sources to the forefront of electrical power production.

But that’s all the more space for future engineers to have an impact and create new solutions to the world’s energy needs!

In this episode we looked at renewable energy sources and why we need them.

We looked at how hydropower, wind, geothermal, and solar power are used to produce electricity,

some of the challenges faced in doing so, and the areas engineers are working on to make their use more widespread.

In our next episode, we’ll see how engineers have moved beyond natural processes, to invent entirely new ways of generating power.

Crash Course Engineering is produced in association with PBS Digital Studios, which also produces Eons, a series that journeys through the history of life on Earth.

With paleontology and natural history, Eons takes you from the dawn of life, through the so-called “Age of Dinosaurs”, and right up to the end of the most recent Ice Age.

Crash Course is a Complexly production and this episode was filmed in the Doctor Cheryl C. Kinney Studio with the help of these wonderful people.

And our amazing graphics team is Thought Cafe.