by Chris Woodford. Last updated: July 5, 2022.
Earth scientists believe the world has
just a few decades about worth of oil still buried in its rocks—but they've been saying
the same thing now for... decades! Whatever the reality about
"peak oil", one thing is certain: with ever-growing numbers of vehicles on our streets, oil is
going to become more expensive and harder to obtain over the next few
decades. That's why many people think the future lies with alternative
fuels made from crops and waste products. Known as biofuels,
these potentially offer many advantages over petroleum. They
could help us tackle global warming
and, by reducing our dependence on oil from the Middle East, they could
help make the world a safer place. But biofuels have major drawbacks
too. Critics think their environmental benefits are overstated and
argue that, by taking land that would otherwise be used for growing food,
they could severely worsen poverty and
hunger in developing countries. Let's take a closer look at how biofuels work
and consider some of the pros and cons.
Photo: Advanced biofuels made from algae. Photo
by Dennis Schroeder courtesy of NREL,
photo ID#40069. One day, every gas station could be pumping out fuel made from plants. Some already have a "Biodiesel" stand
with pumps offering a choice of several common blends, including B20 (20% biodiesel and 80% ordinary diesel), E85 (85% ethanol and 15% gasoline), and E10 (10% bioethanol and 90% gasoline), also called gasohol.
What are biofuels?
A fuel is something we burn
to release energy in a chemical reaction called combustion,
which goes like this:
Fuel + oxygen (from the air) → released
heat energy + carbon dioxide (CO2) + water (H2O)
The exact chemical reaction depends on which fuel you burn, but
broadly the same process is at work whether you burn natural gas in a
central-heating boiler, wood on a camp fire, gasoline in a car engine, or coal in a power plant.
Almost any organic
(carbon-based) substance can be a fuel. Our commonest fuels are such
things as coal, oil, gas, peat, and wood—all of them made from hydrocarbons (molecules built from
hydrogen and carbon atoms) and all of them
ultimately derived from living things (either dead plants or animals).
Strictly speaking, the word biofuel can mean any fuel made from living
organisms or their waste—which means most of our fuels are biofuels.
But we normally use the word "biofuels" in a much more restricted sense
to talk about liquid and gas vehicle fuels made from crops or waste
products. The best-known biofuels are ethanol
(an alcohol made from sugar beet)
and biodiesel made from vegetable oil.
Types of biofuels
Photo: Most biodiesel in the US is made from
soybeans, like these, or recycled cooking oil.
Photo by Scott Bauer courtesy of US Department of Agriculture Agricultural Research Service.
Biofuels are a hot environmental topic at the moment, but they've
been around for many decades. People who work with them often talk
about first-, second-, and third-generation biofuels to distinguish between
simple, traditional biofuels that have been used for a long time and
the more complex, more advanced, and more efficient ones that are
currently in development.
- First-generation biofuels
include such things as vegetable oil, biodiesel, ethanol, and methanol.
Ethanol and methanol are very strong alcohols made from sugar, wheat,
or corn in a process similar to brewing. Vegetable oil made from such
things as peanuts and soybeans can be burned directly as a fuel, or it
can be turned into biodiesel, a gasoline substitute (or additive) that
can help to reduce vehicle emissions.
- Second-generation biofuels
are made by turning crops into liquid fuels using more sophisticated
chemical processes and include such things as BioHydrogen (hydrogen gas
made from crops) and mixed alcohols. They are generally more efficient
than first-generation biofuels because they release more energy per
volume, so you can go further on a tank filled with them. It also helps
if you are growing crops to make fuels, because it means you have to grow fewer plants and cultivate less land
to produce the same amount of energy.
- Third-generation ("advanced") biofuels
are made using oil produced from algae, grown in ponds or closed reactors, which
is refined to make conventional fuels like biodiesel, methane, ethanol, and so on.
The big advantage of algae-derived fuels is that they don't need vast amounts of farmland;
the big drawback is that they need lots of water and fertilizer, which greatly increases the cost and environmental impact, potentially wiping out any benefit.
Photo: In the future, will most of our biofuels be made from algae like this?
Photo by Dennis Schroeder courtesy of US Department of
Energy/National Renewable Energy Laboratory (DOE/NREL).
What are the benefits of biofuels?
If you read the news, you'll have seen a great deal of coverage
about biofuels in the last few years. The basic idea is certainly very
attractive: instead of pumping oil out of the ground and shipping it
round the world, we could produce biofuels from crops and waste
instead. For a country such as the United States, which is hugely
dependent on oil from the Middle East (the world's most politically
unstable region), a plan like that has huge attractions.
How much difference could biofuels make? Organizations like the International Energy Agency have
highlighted enormous potential. In its Biofuels for Transport Roadmap, published in 2011, the IEA suggested
biofuels could produce 27 percent of the world's total transportation fuel by 2050
(over a 10-fold increase from today). Such an ambitious project would need 100 million hectares (Mha) of land (roughly the area of South Korea).
Sounds good? There's another great benefit too.
The IEA's roadmap would reduce total world carbon dioxide emissions by 2.1Gt (a little under 10 percent of the current global total). Normally, burning fuels such as petroleum,
coal, and gas (which were made millions of years ago) releases carbon
dioxide into the air—in other words, it increases emissions.
This gas smothers Earth like a huge invisible
blanket, heats the planet—the problem we now call global warming—and is starting to
climate. In theory, biofuels don't suffer from the same problem. When a
tree grows, it absorbs carbon dioxide (CO2) from the
air, and water (H2O) from the soil, and uses sunlight to
convert the carbon, hydrogen, and oxygen from these molecules into more
complex carbohydrate molecules (sugars and starches) that it stores.
This process is called photosynthesis and
it's a little bit like combustion running in reverse. Through
photosynthesis, a tree uses carbon dioxide to grow. If we burn the tree
as a fuel at the end of its life, the process of combustion releases exactly
the same amount of
carbon dioxide as the tree absorbed when it grew. So biofuels are (at
least in theory) carbon neutral:
growing a tree (or any other plant) and then burning it as a biofuel
doesn't add any carbon dioxide to the atmosphere or make global warming
Photo: As you read this, scientists are working hard
to develop the next generation of biofuels.
Photo by Scott Bauer courtesy of US Department of Agriculture Agricultural Research Service.
What are the drawbacks of biofuels?
If it were only that simple, we'd be growing biofuels like crazy and
switching half the planet to biofuel production tomorrow.
Unfortunately, biofuels have some drastic drawbacks.
Imagine you're a farmer. You've heard great things about biofuels
and how they can help to save the planet, so you decide to convert all
your fields to soybeans and produce biodiesel. You'll need energy to
power your tractors to plant the fields and harvest them and more
energy to ship the beans round the world. More energy will be needed to
power the chemical plants that turn the beans into biodiesel and even
more will be needed to transport the finished biodiesel to the vehicles
that use it. Using all this energy means burning fuel and releasing
carbon dioxide. You may be trying to help the planet reduce its carbon
dioxide emissions, but you're actually generating quite a lot of the
very gas you want to prevent in growing, processing, and transporting
your crops! That means biofuels are not actually carbon neutral at all.
According to research funded by the
US Department of Energy, ethanol from corn
produces 19–48 percent fewer carbon dioxide emissions, while
cellulose-produced ethanol could reduce emissions by as much as 115 percent.
But other studies have discovered that the entire process of producing biofuels can generate more
carbon dioxide than the fuels themselves save (which casts
considerable doubt on whether some biofuels are worth growing at all).
In 2016, for example, The Guardian reported that biodiesel from palm oil produces three
times the emissions of fossil fuels, while oil from soybean produced twice
Who is correct? And how can ordinary consumers hope to make sense of it? One solution could
be eco-labeling, in which properly sustainable biofuels are certified
by a credible, independent third-party. In May 2016,
The New York Times reported that Pacific Biodiesel's Hawaii plant
had become the first in the United States to be granted a certificate of sustainability
by the Sustainable Biodiesel Alliance.
Photo: Giant farm machines use huge amounts of
These tractors and harvesters at the Beltsville Agricultural Research
Center run on a mixture of diesel and biodiesel made from soybeans.
Photo by Bob Nichols courtesy of US Department of Agriculture Agricultural Research Service.
Relatively little land is needed for oil rigs and pipelines compared
to the size of the vast underground oil fields that they tap into (not
least because many oil fields are offshore). The same is not true of
biofuels: enormous amounts of land are needed to grow the crops. If you
planted up a forest on top of an old strip mine and harvested the trees
to make biofuels, there'd be a net benefit to the planet. But what if
you felled and burned a large area of rainforest to grow palm oil for
making biodiesel? Then you'd be releasing a huge amount of energy by
burning the trees, the planet would no longer benefit from the trees
growing and removing carbon dioxide, and we'd lose the forest's
wonderful biodiversity (its dense collection
of animals and plants).
You might think you were making "environmentally friendly biofuel," but
you'd be doing so much damage in the process that there could be an
overall negative impact. This problem is already occurring in
developing countries where forests are being felled (because they have
no immediate financial value) to grow lucrative crops for biofuels.
Mark Avery, former conservation director of the UK charity RSPB (Royal
Society for the Protection of Birds) and a vociferous opponent of biofuels, argues that this "threatens to accelerate the destruction of some of the world's most precious
habitats and wildlife. Without environmental standards, biofuels will
be little more than a green con."
Chart: Who produces the most biofuels? America (North, South, and Central) produces about two thirds of the world total. Africa, CIS (Russia and associated republics), and the Middle East combined produce less than 1 percent of the total. Inner ring shows data for 2019, middle ring shows 2020, and outer ring shows 2021.
Drawn by explainthatstuff.com using data from BP Statistical Review of World Energy 2022, p.48.
Fuel versus food?
There's only so much land in the world, but the number of people
has to support is increasing rapidly. As oil becomes more expensive,
so biofuels become more attractive to grow. That means farmers
may find they can earn more by growing biofuel crops than food crops,
which could lead to food shortages and increasing food prices. People
in developing countries (already with the greatest struggle for
will be hardest hit by any rise in the price of basic commodities such
as wheat. In our haste to use biofuels to tackle global warming (one of
the world's most pressing problems), it's possible we could worsen
world hunger and poverty (two of the world's other pressing problems).
According to Action Aid, a poverty-fighting charity, in an undated briefing they wrote
around 2011 or 2012: "If biofuels targets set by the U.S. and Europe are
met the amount of land used to create fuel rather than food will increase dramatically. The result?
Food prices could rise by up to 76% by 2020, pushing 600 million people into hunger."
Since then, Action Aid has attributed significant food price increases in Mexico to the use
of corn ethanol in the United States and major environment impacts to
the expansion of ethanol production in Brazil.
Not everyone agrees with this assessment. Some think growing biofuel
crops could be a lifesaver for farmers in both developed and developing
countries. According to the
Organisation for Economic Development (OECD),
worldwide biofuel production has tripled over the last decade.
In theory, that massively growing market for agricultural produce should be great news for farmers; in practice, things aren't so simple. Growing questions over the sustainability of
biofuels could see many farmers, who've invested heavily in biofuel production, left high and dry.
(See, for example:
New EU biofuels law could be last straw for farmers hit by wet weather and rising costs", The Guardian, October 14, 2012.)
Some argue that biofuels could bring benefits for developing countries. According to
Peter Kendall, president of Britain's National Farmers Union: "What has
been holding back agriculture in the developing world is not a shortage
of land, but the rock-bottom prices caused by the fact that world
markets have been swamped by surplus grain, from both the EU and US. If
the demand for biofuels helps to change that, directly by lifting
prices and indirectly by mopping up the surpluses, then it will give
Third World farming the biggest single boost it has ever had. That, in
turn, will do more to alleviate starvation in Africa and elsewhere than
all the food aid programs put together." (Quoted in: Biofuels 'will
not lead to hunger', BBC News Viewpoint, October
Chart: Total biofuel production has increased by about 100 percent in the last decade, with a current annual rate of growth (in 2021) of 4.1 percent (compared to 3.5 percent in 2017). Drawn by explainthatstuff.com using the latest data from BP Statistical Review of World Energy 2022, p.48 ("Renewables: Biofuels production") and previous annual editions.
Power to the people?
Photo: Power to the people: This truck driver
could be helping save the planet by filling up with 95% ethanol, a fuel made
from corn. It's just the same as filling up with ordinary diesel or
gasoline, but the truck's engine has been specially modified.
Photo by Warren Gretz courtesy of US Department of
Energy/National Renewable Energy Laboratory (DOE/NREL).
In theory, biofuels give local communities the power to grow their
own fuel and lead self-sufficient, sustainable lives with little impact
on the planet. There's nothing to stop anyone making their own
biofuels by growing "energy crops" on their own land or producing their
own biodiesel from waste
products. Indeed, When Rudolph Diesel (1858–1913) invented his
diesel engine in the 1890s, he envisaged people doing just this: his vision
was one of local communities growing crops to run their engines and
making themselves entirely self-sufficient in energy in the process.
Ironically, Diesel's community-spirited ideas were quickly lost and
forgotten. Today, hardly anyone makes their own fuel; virtually all
diesel engines run on petroleum pumped from the ground by multinational
oil companies in a centralized, globalized market. Just as huge
multinationals dominate oil production,
so they are already dominating the production of biofuels. Far from
taking control of their own future, local communities in such places as
Kalimantan, Indonesia have been forced from their land so that large
companies can fell their forests, strip the land, and grow palm oil for
making biodiesel. (See, for example, the Greenpeace briefing "Palm Oil").
Venture capital firms, genetic engineering corporations, oil firms,
and car firms have already moved in on what they see as the next hugely
lucrative business opportunity. Some would see that as a good thing.
The world has a huge investment in burning oil and it will take a
herculean effort (and massive investment) to switch people over to more
forms of power. But, on the other hand, are we simply switching
all the problems of an oil-dependent economy for a different
set of problems with biofuels?
Biofuels: good or bad?
On balance, then, the case for biofuels isn't nearly so clear cut as
it seems. If they're produced in a responsible way, biofuels could help
us cut carbon dioxide emissions and tackle global warming. But in the
dash for profit, there's a risk they could lead to greater emissions
and significant loss of biodiversity and exacerbate
problems such as poverty and hunger in developing nations. With limited
world resources and a growing global population, perhaps it makes more
sense to try to cut the energy we use and
reduce our dependence on cars
than simply to substitute biofuels for
oil and carry on as we are. Scientists are urging us to act quickly to
reduce the impacts of global warming, but it might
pay us to take a bit more time with biofuels and act more wisely. In
to protect the planet, we have to be absolutely certain we're not
helping to destroy it.