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Natural Gas, the Perfect Bridge to Renewable Energy - Part 2

By Barry Stevens | Thu, 20 December 2012 22:45 | 3

continued on from part 1.

So what is natural gas?

Natural gas is a mixture of hydrocarbons that varies across the board, depending on where it is found, but its chief component is “methane”, which usually makes up about 80-95 % of the gas. The rest of the gas consists of varying amounts of other small chain hydrocarbons like ethane, propane, and butane. The chemical formula of Methane is CH4. By weight, methane is 60% carbon. Carbon content is important in terms carbon emissions, which we will discuss shortly.

Gasoline is a complex mixture of over 150 hydrocarbons that may have between 5 to 12 carbon atoms per molecule. Octane with 8 carbon atoms is the principal component of gasoline. Gasoline may also contain chemicals such as corn ethanol, lubricants, anti-rust agents and anti-icing agents that are added to improve vehicle performance. The chemical formula of Octane is C8 H18.  By weight, gasoline is 73% carbon; an increase of 13% over natural gas.

Coal varies widely in its composition containing both combustible organic compounds and inorganic impurities.  It’s composed chiefly of rings of six carbon atoms joined together in a highly complex composition of layered arrangements that has significant amounts of oxygen and nitrogen and trace amounts of sulfur and other environmental pollutants such as mercury, arsenic, cadmium, lead and zinc.  Mercury and sulfur are present in hazardous concentrations. The chemical formula of coal has been approximated as C135 H96 O9 NS. By weight, coal is 81% carbon; an increase of 21% over natural gas.

Natural gas is the cleanest of all the fossil fuels, as evidenced in this chart; coal – green; Petroleum – blue; Natural gas – light blue columns. The level of each primary pollutant is presented as percent difference from coal, where coal is given a relative value of 1. For example, the CO2 level of oil is about 80% that of coal. The CO2 level of natural gas is about 55% that of coal, and so on with the other pollutants.

EIA Natural Gas Issues and Trends
Source: EIA Natural Gas Issues and Trends

Because of their complex make up, when combusted, coal and for the most part oil emit higher levels of carbon dioxide, carbon monoxide, nitrogen oxides (NOx), and sulfur dioxide (SO2). Coal also releases ash, particulates and mercury into the environment, substances that do not burn but instead are carried into the atmosphere and contribute to pollution.

The combustion of natural gas, on the other hand, releases very small amounts of sulfur dioxide and nitrogen oxides, with virtually no ash, particulate matter or mercury, and lower levels of carbon dioxide, carbon monoxide, and other reactive hydrocarbons.

What Is Renewable Energy

The effort to reduce the world’s dependency on fossil fuels is approached in two different ways – clean energy and sustainability. Where, clean energy refers to renewable energy technologies and sustainability usually refers to energy conservation achieved through energy efficiency programs.

Looking at clean energy, there is much debate about how to define and distinguish renewable from non-renewable energy, and the terms and definitions chosen can have huge impacts on policy and regulatory efforts aimed at promoting clean energy resources.

The definition of renewable energy seems clear cut: The sun continues to shine, so solar energy is renewable. The wind continues to blow, so wind turbines churn out renewable power. “But what about a banana — you can just about grow them forever and when it goes into the garbage and gets burned,” it produces energy and emissions.”   Also, if seemingly clean sources of energy have a long history of use, such as conventional hydropower or dams, why not classify it as renewable. The prevailing thought is by considering existing dams a renewable source of energy it would allow utilities to satisfy any renewable-energy mandates, and therefore, provide little incentives to install new clean energy facilities such as wind, solar or tidal power.

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Environmentalists argue that one of the goals of renewable energy is to cut back on the heat-trapping gases emitted from burning organic matter, whether fossil fuels or bananas. Where there is no fire, there are no emissions. A purist would not consider burning bananas a renewable resource.

As a tradeoff, renewable energy can be considered any new energy resource that is naturally replenishable, but flow-limited. That is they generate energy only when the wind is blowing or sun is shining. They are virtually inexhaustible in duration but limited in the amount of energy that is available per unit of time.

Geothermal, biomass and bananas may be stock-limited in that stocks are depleted by use, but on a time scale of decades, or perhaps centuries, they can probably be replenished. Coal and oil can take hundreds of millions of years to form. Of the fossil fuels, only natural gas can be produced anywhere from a few years to hundreds of millions of years.

Furthermore, renewables do not produce toxins or pollutants that are harmful to the environment.
Renewable energy resources are derived:

• directly from the sun, such as   - thermal,   - photochemical,   - photoelectric.
• indirectly from the sun, such as    – wind,   - hydropower,   -  photosynthetic energy stored in biomass and bananas.
• or from other natural movements and mechanisms of the environment, such as   – geothermal,   -  tidal energy.

What is Sustainability

The trend is clear; the world has to steadily improve its ability to produce more with less energy. Concerns about energy affordability, energy independence, profitability, a clean environment and reduced GHG emissions have heightened interest in the potential for sustainable practices to help address these important issues.

In this sense, renewable energy and sustainability have the same bottom line goals of conserving resources and providing a cleaner environment.  However, they tackle this goal in different ways. In this sense they are separate parallel activities leading to reduced carbon usage.

Sustainability is an approach or even mindset in the sense of an organization and its operation’s simultaneous and balanced concern for:

• People – in terms of an improvement towards labor, the community and region,
• Planet – in terms of benefits towards the ecology and the environment, and
• Profits – in terms of real economic benefits enjoyed by the residential, commercial and industrial sectors.

This combination of people, planet and profits are referred to as the triple bottom line.

The key words in defining sustainability are “organization” and “profits.” Rather than the utility base approach of renewable energy, sustainability is the responsibility of an organization and what that organization can do to conserve energy and save money. Their interest is to improve their own balance sheet rather than the balance sheet of other organizations. It’s a matter of internal energy waste management and the programs they implement to reduce their utility bills and operation expenses.

Therefore, the main point of departure between renewable energy and sustainability is how, where and why they are used. Renewable energy is fuel-based and for the most part involves fuel-switching by utilities as a result of policy mandates.

On the other hand, sustainability is organizational-based and for the most part involves implementing energy efficiency programs in the need to reduce expenses. Industries can be more competitive by saving energy and cutting costs and thrive in the global economic landscape.

Overall, society needs both sustainable and renewable resources. Neither precedes or succeeds each other. We can immediately benefit from the implementation of energy efficiency programs while working diligently on a broad spectrum of renewable energy technologies. In this way, we will continuously reduce our dependence on fossil fuels, improve the environment and reap significant financial benefits.

Levelized Cost of Energy

To determine the most economical technology for the type of demand for which new capacity is needed, a model was developed that compares the technologies based on the economics of their Levelized costs. The Levelized cost of electricity or LCOE is a convenient summary measure of the overall competiveness of different generating technologies.

Levelized cost represents, the per kilowatt hour cost of building and operating a generating plant over an assumed financial life and duty cycle. It assumes a 30-year cost recovery period.

Key inputs to calculating LCOE include overnight capital costs, fuel costs, fixed and variable operations and maintenance (O&M) costs, financing costs, and an assumed utilization rate for each type of plant.

The following chart shows the estimated Levelized cost of new electricity generating technologies in the U.S. for a variety of fossil fuel and renewable energy plants.  Each column of the graph is divided into the various financial components of Levelized cost:

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• capital costs are illustrated by the green section of each column
• fixed O&M  -  purple
• variable O&M  including fuel -  light blue, and
• transmission investment  – dark blue sections.

Alongside each colored column is a gray bar representing the utilization rate for each plant type, which is the ratio of the actual output to its potential output had it operated at full nameplate capacity the entire time. The trend emerges that the lower the utilization rate the higher the LCOE.

U.S. EIA Levelized Cost of New Generation Resources
Source: U.S. EIA Levelized Cost of New Generation Resources

Clearly, the lowest plant costs are natural gas-fired power plants at $80 per MWh. At the other extreme are solar PV power plants at nearly $400 per MWh.

Traditionally natural gas had trouble competing on the variable cost portion but was much more capital-efficient to build. Today, coal-fired plants have skyrocketed in costs due to uncertain future fuel prices and environmental compliance costs.

It’s projected that the spread between coal and natural gas will continue to increase making gas-fired plants more attractive. This has made it very difficult for other energy sources to compete with gas.

The demands on coal-fired plants have made biomass power stations a competitive option. The Levelized costs steadily increase from biomass and geothermal to nuclear and hydro, before skyrocketing to wind and solar power.

Nevertheless, renewable energy, and in particular, bioenergy have great potentials for increased utilization. Bioenergy is the front runner of renewable energy due to its conversion of waste into energy, where waste is generated on all corners of the earth and presents a worldwide problem with its ever increasing buildup and disposal issues. Recycling biomass to generate energy is a highly attractive option.

Without question, the most important barrier to a larger?scale implementation of all of these low carbon technologies comes down to one factor: the cost of the technology, and in particular, the private cost born by the organization implementing the technology.

Technological, regional and policy factors can influence investment decisions including technological and regional characteristics of a project, such as:

• the existing resource mix in a region,
• capacity value, which depends on both the existing capacity mix and load characteristics in a region,
• policy-related factors and incentives for specified resources,
• the uncertainty about future fuel prices and future policies may cause plant owners or investors who finance plants to place a value on portfolio diversification rather than the Levelized cost, and
• penalties and taxes.

The Bridge to the Future

Any projections on the future of the world’s energy production, consumption, and trends are marked with many uncertainties. World economics, politics, environmental concerns, and new technological advances can alter any projection.

Bridge

Like it or not, renewable energy has a long way to go to make an impact on any one country’s energy inventory.

Throughout this discussion, natural gas has emerged time-and-time again as a realistic option to many of the world’s energy problems.  Natural gas, the least disruptive fossil fuel, could serve as a ‘bridge’ to a low-carbon future.

Every year more and more power is generated by natural gas and less by coal. Fuel-switching power generation to natural gas makes economic and practical sense.

Just about every internal combustion engine could run on natural gas. Natural gas fueled vehicles could make the impact on reducing petroleum consumption that Electric Vehicles (EVs) hoped to achieve.

Natural gas is a step in the right direction.

It’s abundant. Recent advances in technology have unlocked vast supplies of natural gas. This map details the presence of technically recoverable unconventional shale gas resources around the world. These reserves are located in 33 countries and make up 22% of the nearly 850 Tcm of proven and technically recoverable global natural gas supplies.

Natural gas is a more efficient source of electricity compared to coal. It takes 60% more coal to produce one (1) kWh of electricity.

Earlier in this discussion natural gas was shown to be a cleaner source of electricity, compared to coal and oil. It is the cleanest of all fossil fuels.

And finally, countries that have capitalized on their shale gas resources found it to have a profound economic impact on:

• creating jobs,
• reducing consumer cost of natural gas and electricity,
• increasing federal, state and local tax revenue,
• stimulating economic growth, and
• reducing GHG emissions and smog.

Under a scenario, that envisions a worldwide momentum towards stick policies aimed at cutting greenhouse gas emissions; electric utilities and other sectors of the economy will have no other choice but to adopt natural gas as a logical alternative.

Natural gas will buy time to further develop, cleaner fuels. Hopefully on the other side of the bridge there will be a viable renewable energy industry, whether its 50 years or the end of the century. But it’s no here today.

By. Dr. Barry Stevens

Leave a comment

  • Ron Wagner on December 21 2012 said:
    Great article that goes to the heart of the subject, which is cost and emissions. An excellent article to use in arguing policy.
  • Neil Clapp on December 29 2012 said:
    Interesting and informative article, but questionable on two points:
    (1) Your assertion that methane (CH4) is 60% by weight carbon, when I get C(12)+4H(1)=16 (mol. wt.) so that
    12/16 = 0.75 or 75%, NOT 60%, and
    (2) Octane (C8H18) was determined early on to have very desirable combustion characteristics, but gasoline produced by catalytic cracking consists mostly of heptane (C7H16) with much less desirable combustion characteristics. Hence so-called "octane boosters" such as tetraethyl lead, aromatic hydrocarbons, alcohols, etc. have been added in varying amounts to increase required activation energy (increase detonation resistance) to some percentage of that of pure octane, expressed as 92 octane or 94 octane, available at increased price levels. This allows consumers at the gas pump to choose their appropriate additive and price levels at costs far below what would be required for equivalent fuels consisting primarily of octane.
  • David Hrivnak on December 30 2012 said:
    You should consider electric cars. They can easily be powered by natural gas, coal, nuclear, wind and solar. They are truely flex fuel vehicles. I checked into natural gas and the electricity to compress the gas into the tank on the car would take more electricity than my EV uses.

    I can drive 200 miles on a charge and it costs me $4 worth of electricity. And better cars with greater range are now shipping.

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