When you see a hybrid vehicle driving down the street such as a Toyota Prius, you may

be thinking about how the person driving it is doing a huge favor for the environment. We all

hear about the phenomenal gas mileage that hybrids achieve and how they emit far fewer toxins

and greenhouse gas emissions than standard vehicles. Maybe you start to consider purchasing a

hybrid as your next vehicle. Everything sounds so great about them… could there possibly be

any downsides? Sure, once you have a hybrid car everything is great right? but what does it take

to build one of these machines, and what happens once we are done with them? Everything looks

good at the surface but once we look a little deeper we can find a number of different

environmental problems involved in the production, disposal and even use of hybrid vehicles.

Before we look into these environmental issues it is important to understand what

qualifies a vehicle as a hybrid and how these vehicles work. By definition a hybrid vehicles is a

vehicle that uses two or more distinct power sources to move the vehicle. This most commonly

refers to hybrid electric vehicles (HEVs), which combine an internal combustion engine and one

or more electric motors. These are the most common type you find today; however there are also

plug-in hybrid electric vehicles (PHEVs), which are hybrid vehicles that have batteries that can

be recharged by connecting a plug to an external electric power source. Either way, the

secondary power source will be an electric motor powered by a large battery. This is mainly

what results in using less fuel, getting more miles per gallon, and lowered emissions. In order for

a vehicle to be considered a hybrid it needs some specific features. First it needs the idle-off

feature which means that the engine shuts off temporarily at stop lights and in stop-and-go

traffic. Ideally the engine will turn itself back on in less time that it takes to move your foot from

the brakes to the gas. The second feature is called regenerative braking. In standard cars the

brakes are the only things working on getting rid of the cars kinetic energy aka slowing you

down. The friction due to the brakes is what does this and all the kinetic energy is converted into

heat. The regenerative braking feature uses the electric motor as a generator along with the

brakes to slow you down therefore harnessing some of the kinetic energy and converting it to

electrical energy which can be used later. In order for this to be effective the vehicle need to have

a large enough electric motor operating around at least 60 volts, and a battery capable of storing

this energy. The third feature a vehicle needs to possess in order to be considered a hybrid is a

given… it needs to have an electric motor to assist the conventional engine. Again the electric

motor and battery have to be significant enough to supplement the engine and help accelerate

while driving. This allows for a smaller, more efficient combustion engine while still

maintaining equal performance. Some hybrids can also drive solely using the electric motor at

times. These cars are called "full hybrids." And finally when a hybrid vehicle can recharge its

batteries from an outlet at your home it is called a PHEV, and these are always full hybrids. So

with all these great features how could a hybrid vehicle possible be harsh on the environment?

The main issues that car companies don’t like to talk about mostly have to do with the battery

that runs the electric motor and all other electrical components in the vehicle.

Three of the most common batteries used in modern vehicles are lead acid, nickel metal

hydride (Ni-MH), and lithium ion (Li-ion). Lead acid batteries are the cheapest and have been

the battery of choice for many years. Since it is the oldest, lead acid batteries do not last as long

as some other batteries and they store less energy. Ni-MH batteries have been used for several

years and store more energy than the lead acid batteries. Lithium ion batteries hold the highest

amounts of energy and are some of the most recent battery technology used and researched on

for today’s modern hybrid vehicles. Lithium is a good choice because it is the lightest of all

metals, has the greatest electrochemical potential, and provides the largest energy density for

weight, typically twice as much as Ni-MH. The reason lithium ions are used is due to the highly

instable nature of lithium. Using the ions is much safer and allows the battery to be rechargeable

without the memory effect that came with the Ni-MH. This battery type also requires very low

maintenance. As you may have guessed however, there are some serious drawbacks to using any

three of these batteries. First of all, all batteries have toxic corrosive carcinogenic ooze inside

them that is terrible for the environment especially when it gets into our waterways and poisons

the groundwater. Lead acid batteries are definitely the worst of the three. Research shows that

long-term exposure to even very small amounts of lead can lead to brain and kidney damage,

hearing loss, and learning disabilities in children. The auto industry uses over one million metric

tons of lead every year, and 90% of it is used in the lead acid batteries. A 2003 report says that

you will find 2.6 million metric tons of lead driving around the roads, and it has only increased

since then. The reason lead has been so popular is because it is so cheap. Fortunately in the

direction we are heading, lead may be at its limit. Hybrid vehicles are example of how modern

vehicles are becoming less mechanical and more electrical. Cars are adding more and more

electrical components, not only for the hybrid aspect of it, but for entertainment and onboard

accessories. Since lead is so heavy, simply adding a larger lead battery to meet all these electrical

needs is not going to be sufficient solution. While it looks like the environmentally unfriendly

lead acid battery may be getting closer to the end of its existence our new batteries may much of

an improvement. We can break up the environmental issues for hybrid vehicle batteries

(specifically Ni-MH and Li-ion) into three simple categories: production, use, and disposal.

According to the federal government Li-ion batteries are not considered a hazardous

waste. However, due to the incredible amount of these batteries in use they still add to the

continuously growing landfills throughout the US. Lithium batteries are not only found in hybrid

vehicles but in many mp3 players, cell phones, and other portable electronic devices. The Li-ion

batteries are the only batteries of the three mentioned that are not toxic as they break down.

Cobalt, copper, nickel and iron which are all contained within the Li-ion batteries are all safe

materials. The government is trying to regulate the amount of batteries being disposed of in

landfills which is due to the ease of throwing out a battery rather than going through the trouble

of recycling. Used batteries don't amount to much return economically when they're recycled

making it difficult for manufactures to put much emphasis on retrieving their used product. This

is not only for the Li-ion batteries. Ni-MH batteries fall into the same category. Laws across the

United States have emerged as an attempt to relieve the vast amounts of batteries being thrown

out rather than recycled. As an example, Minnesota requires that 90% of all Ni-CD batteries be

recovered though even with the requirement they've never been able to recover more than 60%.

If the number of PHEV’s on the road increased, an increase in mining would provide

plants with enough coal to generate electricity to run all these vehicles. But coal mining itself

releases large amounts of waste containing toxic heavy metals like iron, zinc, and chromium and lead

acid. Results of polluted surface and ground water are prevalent as well as greenhouse gasses being

burned. A Minnesota Pollution Control Agency study found PHEVs could actually emit more greenhouse

gases than conventional vehicles. Sulfur dioxide being the pollutant in greatest amount, PHEVs would

emit double the amount than conventional vehicles, and three to four times than a regular hybrid. Sulfur

dioxide is toxic and what is in acid rain.

Hybrids also require more rare earth metals than conventional vehicles, requiring more mining.

Broken down; the greater the charge needed to run a hybrid vehicle, the more possible pollution

following an electric utility’s generation.

Although there is a growing demand for the development of hybrid or even electric cars

for environmental reasons the best question is how would a stream of hybrid cars really effect

overall pollution? Hybrid cars for example would produce much less pollution in certain areas

like densely populated areas. However, hybrids still use their combustion engine while driving

on the highway. Another major factor is in the sheer weight of these massive batteries needed to

provide enough power for a vehicle. Hybrid cars certainly don't have the power that the strictly

combustion engines can provide and with the added weight there is much more energy required.

A recent study took into consideration how much weight affects the economic performance of a

vehicle. Using a steel framed conventional vehicle as the base of the study, weight reduction was

compared to hybrids and diesel engines. It was found that the cost per unit mileage was the

greatest in the hybrid vehicle. Even when the weight of the hybrid was decreased, the cost per

mile was still greater than both the diesel and the combustion vehicles. By decreasing the weight

of a normal combustion vehicle the overall fuel consumption could be reduced by 11-12 percent.

This shows that even though the immediate pollution coming directly out of the exhaust for a

combustion engine in our automobiles today could be reduced by driving hybrid cars, the overall

cost and energy consumption is actually greater. The other aspect of the electric based engines is

the PHEV's which can be plugged into any household plug and charged during off peak times.

Similar to the hybrid cars this would provide an initially clean way to travel but even plugging

these cars in will in turn produce some form of pollution. Coal is still one of our main sources for

power across the United States, generating 49% of electricity. Therefore by plugging in your

PHEV, you're in turn just burning more coal somewhere in the US to provide that nice clean

drive to work. If the majority of our power were produced through solar or wind energy then this

new electric form of transportation could be very beneficial to the health of our environment but

as is, it is not the case.

The race for better batteries may lead to a future decrease in overall pollution however; at

present it seems the demand is to alleviate the large quantities of oil that is being imported from

overseas to allow us to fuel our current vehicles.

Primary lithium-ion and lithium-ion secondary are the two types of lithium-ion batteries.

The lithium-ion secondary batteries are used mostly in hybrid vehicles because of its more

favorable characteristics. The primary LIBs contain use of metallic lithium as a cathode and

contain no toxic metals. And if the metallic lithium is exposed to moisture while corroding, there

is chance the cell will light on fire. On the other hand, secondary LIBs contain no metallic

lithium and instead use other elements at its positive and negative electrodes. Slight variations of

heavy metals, organic chemicals, and plastics make up secondary LIBs, and are toxic and

flammable. These batteries are rechargeable and preferred for use because they are lightweight,

high in energy, and perform well. The ways to dispose of lithium-ion batteries include:

mechanical separation (dismantling), thermal treatment, a mechanochemical process, dissolution,

acid leaching, bioleaching, solvent extraction, chemical precipitation, and an electrochemical

process. Dismantling is the initial action in recycling spent batteries. To extract desired waste

from the material, several mechanical processes are done. A material can be crushed, sieved,

magnetically separated, fine crushed, and classified to yield a certain feature, though actually

retrieving all components is difficult to do. Thermal treatment, mechanochemical process, and

dissolution have advantages like efficiency, but disadvantages like cost. Leaching, solvent

extraction, and chemical precipitation are also highly effective in recovering recycled metals, but

are also high in cost. When proposing these types of recycling processes to an industry level of

operation, it may seem unrealistic. Most products from the recycling processes can be reused in

manufacture and offer incentive to recycling of these batteries.