2.3 Non-renewable Generation

Non-renewable energy comes from sources that will, at some point, run out and not be replenished.

Introduction

Most non-renewable energy sources are fossil fuels, such as coal, petroleum, and natural gas. Carbon is the main element in fossil fuels, and that’s why the time period during which fossil fuels formed (about 300-360 million years ago) is called the Carboniferous Period.

Let’s learn more about the process by which the raw materials of fossil fuels are created.

1. Prehistoric swamps: All fossil fuels formed in a similar way. Hundreds of millions of years ago, even before the dinosaurs, Earth had a very different landscape and was covered with wide, shallow seas and swampy forests. 2. Dead organisms: Plants, algae, and plankton grew in these ancient wetlands. They absorbed sunlight and created energy through photosynthesis. When they died, the organisms drifted to the bottom of the sea or lake, and energy was stored in their remains. 3. Fossilization: Over time, these dead organisms were crushed under the seabed. Rocks and other sediment piled on top of them, creating high heat and pressure underground. In this environment, the plant and animal remains eventually turned into fossil fuels (coal, petroleum, and natural gas).

Today, there are huge underground pockets (called reservoirs) of these non-renewable sources of energy around the world.

Nuclear Generation

Unlike many other non-renewable energy sources, nuclear generation does not rely on fossil fuels. Instead, nuclear power comes from the process of nuclear fission, in which a heavy atomic nucleus is split, resulting in the release of large amounts of energy. In the carefully controlled environment of a nuclear reactor, this energy is used to generate heat and then steam, which in turn rotates turbines to generate electricity.

Uranium fuel

Nuclear power is considered non-renewable, primarily because the uranium fuel source it currently relies on is finite. However, it is not a fossil fuel, and it is a significant producer of electricity that is generated without creating greenhouse gases.

Baseload generator

Nuclear generation is a large and reliable source of baseload electricity generation—that is, the minimum amount of electricity that we need to have consistently available. Nuclear power plants are well suited to this role in part because they cannot be easily turned on and off.

Small Modular Nuclear Reactors (SMRs)

Small Modular Nuclear Reactors (SMRs), or micro nuclear units, are also being actively developed in Canada, and have the potential to replace fossil fuel-based generation in remote communities and at industrial sites.

Advantages and Disadvantages of Nuclear Power

Advantages

• Non-emitting with zero carbon emissions

• Provides reliable, always-available baseload generation

• Can provide significant centrally generated electricity

• Low cost over time

Disadvantages

• High upfront capital costs and long project timeframes

• Public perception regarding potential safety concerns

• Questions regarding disposal of nuclear waste

Coal Generation

Coal is an abundant and inexpensive energy source with a long history. It provides 40% of the world’s electricity. Traditionally, coal is crushed and turned to powder, then burned to produce steam, which in turn rotates turbines to generate electricity.

Recent advances have allowed “clean coal”-based electricity production through scrubbing technology which traps carbon emissions prior to release to the atmosphere. This has moderated some of the environmental concerns. Coal can also be converted to cleaner burning liquid hydrocarbons and synthetic gas.

In 2005, coal represented 18% of Canada’s generation mix. By 2019, coal generation had been reduced to 8%. Ontario eliminated coal generation in 2014, and federal regulations require a phase out of traditional coal-fired electricity generation across the country by 2030.

Advantages and Disadvantages of Coal Power

Advantages

• Coal is plentiful in supply and inexpensive

• Relatively inexpensive to build coal generation plants

• Provides reliable, always-available baseload generation

• Coal is easy to burn and produces high energy

Disadvantages

• High intensity of greenhouse gas emissions

• Emits heavy metals such as mercury

• Has been linked with acid rain

• The coal extraction process can be detrimental to the environment

Natural Gas Generation

Natural gas is found in underground reservoirs. It is the cleanest burning of all the fossil fuels and emits approximately half the carbon emissions of coal when used to produce electricity.

Natural gas is burned to produce steam, which in turn rotates turbines to generate electricity. Natural gas generation plants have the advantage of being able to start up and shut down with relative ease, making them an effective means of meeting electricity demand spikes.

Alternative uses

Natural gas can also be used as a fuel source for combustion-engine-based electricity generation, which is often used for emergency back-up purposes.

Transition fuel

As efforts have intensified to reduce carbon emissions, natural gas has been widely used as a replacement for coal and oil in electricity generation. In this context, it is sometimes referred to as a transition fuel, meaning one that will help bridge the gap between traditional fossil fuel dependence and larger-scale use of renewables.

Advantages and Disadvantages of Natural Gas Power

Advantages

• Abundant

• Inexpensive

• Easily transported

• Produces less overall pollution than other fossil fuels

Disadvantages

• Produces greenhouse gases

• Public concern about production—especially when gas is extracted using fracking

Oil Generation

Oil can be burned to generate steam for electricity production, or oil distillates can be used to run a diesel engine which powers a generator. In Canada, however, oil as a fuel for electricity production has been largely replaced by natural gas, due to its cost, efficiency, and other advantages.

Diesel generation continues to be used in remote locations such as the North, or in other areas not easily served by the electricity grid.

In terms of cleanliness and greenhouse gas emissions, oil falls between coal and natural gas, with natural gas being the cleanest of these three fossil fuels.

Advantages and Disadvantages of Oil Power

Advantages

• Has been in plentiful supply

• Has an established transportation system

Disadvantages

• Produces greenhouse gases

• More expensive than coal and natural gas

• Less efficient than natural gas

Hydrogen Generation

Although not a large electricity generation source today, hydrogen is garnering much interest. It is odourless and colourless, and the most abundant element in the universe. But it does not exist freely in nature and must be produced using other energy sources. It is therefore referred to as an energy carrier.

Grey hydrogen

This most common form of hydrogen is generated from natural gas or methane through steam reforming.

Blue hydrogen

This form of hydrogen is produced in the same way as grey hydrogen, but the resulting greenhouse gas emissions are captured and stored.

Green hydrogen

This form of hydrogen is produced using clean renewable electricity and an electrolysis process, and results in no greenhouse gas emissions.

While hydrogen is renewable in and of itself, production of hydrogen today overwhelmingly relies on non-renewable sources such as coal, natural gas, and oil. These are used to separate hydrogen from oxygen through a steam reforming process.

Renewable Hydrogen

Hydrogen contains a large amount of energy in its chemical bond. It is a clean-burning fuel, and when combined with oxygen in a fuel cell, produces heat and electricity with only water vapour as a by-product. As utilities continue to transition to renewables, there is growing interest in the production of green hydrogen. Hydro-Québec, Evolugen, BC Hydro, and ATCO, for example, are among the companies that have readied themselves to enter the renewable hydrogen industry.

Ease of transport

Hydrogen can be stored in tanks, transported by road and sea, and even piped through the existing natural gas grid to power households and industry, to produce chemicals, and to fuel cars, trains, and trucks.

The hydrogen economy

If renewable hydrogen becomes commercially viable to produce, it could become an important new export opportunity for Canada while helping the world to decarbonize.

Some envision a future “hydrogen economy,” where hydrogen is produced from a variety of energy sources, stored for later use, piped to where it is needed, and then converted cleanly into heat and electricity.

Advantages and Disadvantages of Hydrogen Power

Advantages

• Significant decarbonization potential, particularly as green hydrogen becomes more viable

• Can be used immediately or can be stored and transported for later use

• Can be used for both electricity generation and as a fuel for transportation and other uses

• Hydrogen vehicles have better range than electric vehicles

• Many countries have identified hydrogen as a key element of their future energy strategies

Disadvantages

• Hydrogen can be volatile and is highly flammable

• Production (particularly of blue and green hydrogen) remains expensive

• Conversion of vehicle fleets, industrial processes, etc. will be required

Carbon Capture and Storage

In addition to the various specific means of producing electricity, further technologies and processes come into play with respect to electricity generation. One of these is carbon capture and storage. Many electricity generation methods generate carbon, but technologies exist that allow the capture and storage of that carbon, rather than allowing its release into the atmosphere.

Why do we need carbon capture and storage?

While innovations in renewable energy are exciting solutions, we do not yet have the technology and infrastructure to make a complete switch to 100% renewables. In the meantime, we must seek ways to reduce emissions from familiar electricity generation sources.

Fossil-fuel-fired electricity remains widespread in Canada and is relatively inexpensive and reliable. The most common fossil fuels used for electricity production are coal and natural gas. However, burning these fuels emits greenhouse gases.

For instance, coal use accounts for 60% of greenhouse gas emissions from electricity production in Canada, while natural gas use accounts for approximately 30%.

Why is carbon capture the solution?

Carbon Capture and Storage (CCS) is the only currently available technology that can reduce emissions from fossil fuel-fired power plants. It has the potential to remove significant proportions of the CO2 emitted from such plants and allows us to strike a balance between emissions reduction and economic growth.

Likewise, as we move toward a lower carbon economy, CCS may find applications in other sectors such as petroleum extraction and processing.

How does carbon capture and storage work?

CCS is a process that extracts and collects the CO2 from a waste gas stream in a power plant. Those potential emissions are then compressed and injected into deep geological formations, whereas they would otherwise go into the atmosphere during electricity production and fuel processing.

CCS is a technological innovation that can be retrofitted to current fossil fuel plants or incorporated into new designs.

Key risk mitigation factors include how we transport the captured C02 and how we choose and manage storage sites to avoid any leakage.

Carbon pricing

A carbon price, whether it is a tax or part of a trading system, increases the cost of carbon-emitting operations—including electricity generation—making investment in lower-emitting technologies more attractive.

Pricing carbon can drive innovation and encourage people and businesses to pollute less. However, relying on a carbon price alone to achieve Canada’s international climate-related targets is not enough.

Although Canada has more than an 80% greenhouse-gas-free electricity mix, we must continue to reduce our contribution to climate change, and CCS technology may be an important means of doing so.

Cogeneration

Cogeneration provides the opportunity to generate both electricity and heat from one source and put both to beneficial use. Cogeneration can be very beneficial at industrial and other sites where there is an ongoing need for both electricity and thermal energy (in the form of hot water or steam).

A cogeneration system can be powered by a variety of fuels including natural gas (the most common choice), biomass, biogas, and waste heat. The use of two energy streams from a single source, together with overall system efficiency, drives savings in both electricity and heating costs.

As larger customers convert to cogeneration options, they can in some cases operate largely independently from the grid, relying on their own self-generated electricity. However, these customers still require grid connection for power back-up purposes, and therefore pay grid standby charges.

Knowledge Check

• Nuclear generation is well suited to baseload generation because it cannot be easily turned on and off.

• Coal is abundant and inexpensive and provides 40% of the world’s electricity supply.

• Natural gas is the cleanest-burning fossil fuel, and it is relatively easy to start up or shut down.

• The use of oil as a fuel for electricity production has largely been phased out in Canada.

• Hydrogen is the most abundant element in the universe, and scientists and engineers are currently exploring its potential application as carriers of electricity.