Question

A homebuilder installs electric baseboard heat and claims, "It is the cheapest and cleanest way to go." Apply your understanding of the second law of thermodynamics (Concept 2-3b, p. 34) and net energy (Figure 13-A) to evaluate this claim.

Short answer

Electric baseboard heat is not the cheapest due to energy conversion inefficiencies and operational costs, particularly if electricity is from fossil fuels.

Step-by-step solution

Understanding the Claim

The homebuilder claims that electric baseboard heat is the cheapest and cleanest form of heating. To evaluate this, we need to understand the cost and environmental impact associated with electric heating compared to other forms of heating, such as gas or oil heating.

Considering the Second Law of Thermodynamics

The second law of thermodynamics states that energy conversion is not 100% efficient. When electricity is generated from a fuel source such as coal or natural gas, energy is lost in the conversion process. This means that electric heating is not as energy-efficient as directly using fossil fuels for heating.

Evaluating Net Energy

Net energy refers to the actual energy available for use after subtracting the energy required to produce, process, and deliver the energy. Electric heating may have lower net energy because a significant amount of energy is lost during electricity generation and transmission, making it less efficient compared to using primary energy sources like natural gas directly for heating.

Considering Environmental Impact

While electric heating is considered clean at the point of use, the overall cleanliness depends on the source of the electricity. If the electricity comes from fossil fuels, then it may not be environmentally clean, due to emissions produced during electricity generation.

Cost Evaluation

For cost, electric heat can be cheaper to install, as it does not require installation of ducts or a combustion system. However, operational costs may be higher if the price of electricity is greater than that of natural gas or oil, considering the inefficiency and energy losses involved.

Key concepts

Second Law of Thermodynamics

The second law of thermodynamics is a fundamental concept in physics that tells us energy transformations are not perfectly efficient. This law implies that whenever energy is converted from one form to another, some of it is inevitably lost as waste heat. For electric heating, this means that when electricity is generated from fossil fuels like coal or natural gas, a significant fraction of the initial energy is lost in conversion processes before it even powers your electric heater.

This loss results in electric heating potentially being less efficient compared to systems that convert energy into heat directly at the point of use, such as gas heating. Understanding this concept helps us critically evaluate claims of efficiency and cost-effectiveness, such as those made about electric baseboard heating.

Net Energy

Net energy is a crucial metric when considering energy sources for heating, as it accounts for the total usable energy that results after all energy losses in the production and delivery processes.

Suppose you want to assess whether electric heat is as energy-efficient as claimed. In that case, it's essential to consider the energy spent on generating, processing, transmitting, and delivering electricity to our homes. Due to significant conversion and transmission losses, the net energy for electric heating can be lower than utilizing energy sources like natural gas or oil directly in heating systems, which often have fewer stages of conversion.

Therefore, understanding net energy enables us to see the whole picture of energy efficiency beyond the points directly inside our homes.

Environmental Impact

Evaluating the environmental impact of electric heating involves considering the entire energy lifecycle.

At first glance, electric heating might seem clean since it doesn't produce emissions at the point of use. However, if the electricity used is sourced predominantly from fossil fuels, the broader environmental picture becomes less clear. The generation of electricity from coal or natural gas releases pollutants and greenhouse gases into the atmosphere.

Therefore, despite being clean in the immediate sense, the actual environmental impact heavily depends on how the electricity powering those heaters was generated. Opting for electricity generated from renewable sources, such as wind or solar, substantially improves the environmental impact.

Electric Heating

Electric heating involves using electrical energy to generate heat, commonly implemented through baseboard heaters, space heaters, or radiant floor heating.

These systems are generally straightforward to install since they do not require extensive infrastructure like ducts or chimneys. They also provide heat instantly and can be highly controllable, making them convenient for homeowners.

• Pros: Simple installation, lower upfront costs, easy control.
• Cons: Higher operating costs if electricity is expensive, potential lower energy efficiency due to conversion losses.

Despite being considered clean, their environmental friendliness often depends on how the electricity is produced, as discussed earlier.

Fossil Fuels

Fossil fuels like coal, oil, and natural gas have long been traditional sources of energy due to their high energy content. However, using them can lead to significant environmental challenges, which is why evaluating alternatives like electric heating is vital.

When fossil fuels are burned to generate electricity, it tells us about the upstream impacts of choices like electric heating. If electric heaters are powered by electricity from fossil fuels, they indirectly contribute to emissions and environmental degradation.

By contrast, a direct use of fossil fuels, like a gas furnace, can be more energy-efficient since fewer conversion processes are involved. Transitioning towards a mix that reduces reliance on fossil fuels for energy generation, such as adopting renewables, is crucial for reducing our environmental footprint while maintaining energy efficiency.