Rechargeable Battery Power – The Missing Link

By Sven Wang

Video Introduction

Overview

Wind and solar dependent on many circumstances

Weather and natural disasters can render this technology unreliable

Green energy power plants (e.g. wind farms) capable of producing sizeable amount of energy

Problem: storing this energy to maximize efficiency

Storing energy in batteries provides greater efficiency and less waste and is the missing link to a green future.

Unreliability of Renewable Energy

Feb 2008 – Texas experienced a slump in wind which led to a 1200-MW drop in energy production

Plant was down for 3 hours, and nearly caused a widespread blackout

Fossil fuel plants had to scramble to provide energy

Most solar/wind plants have back-up fossil fuel plants which stay on standby mode until needed

Burn fuel while on standby mode 24/7 Can cancel out some of the green energy

produced by solar and wind

Unreliability of Renewable Energy

Chart from California study Shows the irregular usage of wind throughout the day

Unreliability of Renewable Energy

Chart from Arizona study Shows intermittency of solar energy output

Unreliability of Renewable Energy Combination of

wind power and fossil fuel plants are used leads to increased emissions of NOx and CO2

Advantages of Battery Power Storage Adjustable energy output depending on current

energy needs over long or short time frames Quick start-up

Fossil fuel plants take 10-20 minutes Energy storage can react on a second by second basis

Absolutely no emissions Uses no water resources Quiet Can eliminate the need for distribution lines (ex:

coal trains)

Advantages (cont)

Easy-to-move equipment if energy requirements change Fossil fuel plants take years to

build and can’t be built in urban areas

Bottom line: battery energy storage synchronizes remarkably well with renewable energy sources to produce no greenhouse gas emissions

History of Rechargeable Batteries

1859 – lead-acid battery invented by Gaston Plante Is the most basic battery with cathode and anode

and a current running through it Was heavy and not very feasible for everyday usage

compared to other, nonrechargeable batteries 1880s – new model of lead-acid battery (Camille

Alphonse Faure) Made a lead grid lattice with lead oxide paste

pressed into the grid Formed a plate that could store electricity Multiple plates could be stacked for greater

efficiency Could also be mass produced

History (cont)

For a while, the basic idea behind the lead-acid battery remained the same

1970 – gel electrolytes replaced liquid Called a gell cell Allowed battery to be used in non-upright

position without leaking or failing 1990s – lithium ion battery was invented

Could store a large amount of charge Was very flexible, allowing it to be

adapted into different shapes Is used in many electronics today

Lead-acid Batteries

Lead-acid batteries invented in 1859 Still in use today because they’re reliable and

cheap Can only store a small amount of energy

though The Trojan Battery Company has begun to

connect lead-acid batteries to form a battery bank capable of storing 1 MW of energy

Lithium-ion Batteries

Electrolytes contained in a low-moisture paste

Have a high energy density (high energy content in a small package)

Expected to become cheaper as there is extensive research in the car industry into these batteries

Used in computer batteries and other electronics

No loss of charge when not in use

Lithium-ion Batteries (cont)

Many tests and projects with li-ion batteries all over the world A123 Systems is doing a demonstration in SoCal

which will integrate 32MW of li-ion battery storage with wind turbines

Currently very popular for small energy requirements

Expected to see huge growth – from $795 million in 2011 to $2.2 billion in 2016

Flow Batteries

Can respond extremely fast (within milliseconds) Chemicals used are stored in tanks when not in use When in use, chemicals are pumped in a circuit

between reactors and tanks Therefore energy storage capacity is limited by

capacity of tanks

Flow Batteries (cont)

Not capable of holding a whole lot of electricity A 20-MWh iron-based flow battery requires 500,000

gallons of tank storage and can only supply the needs of 650 homes for a single day

Research is being done to drastically improve this statistic

Even More Types of Batteries

US Advanced Research Projects Agency-Energy (ARPA-e) is sponsoring a multitude of different energy storage projects Projects are still in research and/or development

stage Examples include metal-air ionic

liquid (MAIL) batteries, planar sodium-beta batteries, etc

Comparison

Different battery technologies have advantages and disadvantages that make it suitable for only certain applications

Still no solution that is practical and economical for everything

Liquid Metal Batteries

Concept proposed in 2009 Also known as liquid sodium or molten salt batteries Main advantages

High energy density Inexpensive and readily available materials

Liquid Metal Batteries (cont)

General idea Two materials are melted and used

to form the positive and negative poles of the battery

Same concept as ionization in solutions in chemistry, except with molten substances

There is an electrolyte layer between the two layers of materials which allow charged particles to move through as the battery is being charged or discharged

Basically a salt bridge that allows charge to move through

The Chemistry of Liquid Metal Batteries

Magnesium (2+) is used as negative electrode on top layer

Antimony (4+) is used for positive electrode on bottom layer

Mixture of salts such as magnesium chloride is electrolyte layer

Overall is very efficient because the cycle can be repeated many times with very little loss of energy

Similar idea to a bartender making drinks with distinct layers

The Chemistry of Liquid Metal Batteries (cont) Discharging process: Magnesium atoms ionize (lose

2 electrons) Positive charge builds up in

magnesium layer Forces magnesium ions to

travel through electrolyte layer to other electrode

Magnesium ions reacquire two electrons when they arrive at other electrode

Become normal magnesium atoms and form an alloy with antimony

Recharging process: Battery is connected to source of

electricity Electricity pushes magnesium out

of alloy and across electrolyte layer back into negative electrode

Progress on Liquid Metal Batteries Currently is still in

laboratory stage So far MIT has been

successful with small batteries the size of a shot glass

Now developing a battery the size of a pizza box - 200x more powerful than smaller battery

Donald Sadoway – one of the big brains behind liquid metal batteries

Progress on Liquid Metal Batteries (cont) Encountering problems with

electrolyte evaporation and breakdown of metal components through oxidation

Require high operating temperatures though (400-700 Celsius) which raises safety concerns

Still is very expensive If perfected, will be the most

cost effective and flexible source of battery energy storage

Disadvantages of Battery Energy

Huge problem: each power plant faces its own difficulties

There is no end-all be-all solution for battery-powered energy storage yet

Large differences in geography and weather require different equipment and infrastructure

Technology is still expensive – need more research

Huge amount of planning needs to go into implementation of battery

energy storage

Government support for energy storage

Success of green programs often depends on government mandates and other incentives (such as tax breaks and subsidies)

Example: green automobiles had government support, as did wind and solar (hence their popularity today)

Currently are not enough financial incentives to make energy storage a widespread thing

What to Take Away

Energy storage in the form of battery power can supplement current renewable energy sources such as wind and solar to make a green future a reality.

Many types of large-scale battery storage are still in development and not yet a reality.

More Information

Lots of cool applications of battery power – check it out if interested: http://www.alternative-energy-news.info/technology/battery-power/

Sources

http://www.smartplanet.com/blog/intelligent-energy/liquid-batteries-a-renewable-energy-game-changer/13146

http://www.renewableenergyworld.com/rea/news/article/2011/08/batteries-for-energy-storage-new-developments-promise-grid-flexibility-and-stability

http://www.articleshare.info/the-history-of-rechargeable-batteries/

http://en.wikipedia.org/wiki/Lithium-ion_battery

http://www.megawattsf.com/index.htm