Biofuel Uses

When using the work fuel, the tendency is the think of the material in question as a liquid for use in automobiles, trucks, and possibly planes. The truth is, biofuels are looked at as a means of replacing ALL of human energy needs from home heating to vehicle fuel to electricity generation. The basic concept is that if we use as much product as we grown, then our net impact on the environment should be negligible if not zero. This article covers a few of the current uses of biofuels, a few of proposed uses, and tries to quantify (or at least mention) the environmental impact.

Transportation

Nearly 30% of all energy consumed in the United States is used in transportation. To put this into perspective, residential and commercial uses combined only account for 10%. That means that humans in industrial nations use, on average, three times more energy to get around than they use to cook their food and heat their homes. This number does not include electricity generation, which accounts for 40% of all energy used.

Globally, transportation accounts for 25% of energy demand and nearly 62% of oil consumed. Most of this energy , two-thirds in fact, is burned to operate vehicles with the rest going to maintenance, manufacturing, infrastructure, and raw material harvesting.  If we delve further into the numbers, we find that upwards of 70% of energy consumption in this segment is used to move people around and that most of this is used in private cars, the least efficient means of transportation. Only 12% of the energy burned by a car goes to moving it and only about 2% is actually used to move the occupants. The rest of the energy is lost to friction, heat, inefficient combustion, and moving about ever more heavy vehicles.

Estimates are that we have hit peak oil or if we have not, it is very near. We won’t actually know that we have peaked until we start down the slope toward the bottom again, but most experts agree that we are quite close. So, oil is running short and when this is combined with the tremendous environmental impact of petroleum recovery, refining, and eventual combustion, the drive for an alternative is clear.

The problem with many alternatives, like wind, solar, etc. is that they simply aren’t practical. Transporting enough stored electricity derived from these mechanisms to make an average journey is very difficult. Many experts believe that practical breakthroughs in these technologies are decades away at best. So, the challenge is to find a fuel that can replace the practical qualities of oil (like being easy to drive around), but which does not pollute the same way.

The solution, at least for now, appears to be algal-based biofuels, which are still years if not decades away from commercialization. The idea is simple. Algae have lipid and lipid can be converted to a number of fuels including diesel, ethanol, butanol, and methanol. Because algae absorb CO2 to make lipid, the net impact on the environment should be very small. Additionally, biofuels are biodegradable, so if they do spill, less harm is done compared to when fossil fuels spill. What is the hold-up you ask? At this point in time, developing fuel from algae requires huge investments of water and fertilizer because the algae must be killed in order to harvest the lipid and then a new stock is grown back up again. The energy needed to grow algae from a seed stock to “harvest-ready” is orders of magnitude larger than the energy obtained from harvesting them. In other words, more energy is put into the system than is taken out, so it leads to a net loss. Until the input of energy is lower than what the system produces (excluding energy from the sun of course), the system will not be viable.

Power Generation

The generation of electricity is the single largest use of fuel in the world. In 2008, the world produced about 20,261 TWh of electricity. About 41% of that energy came from coal, another 21% came from natural gas, and the rest was covered by hydro, nuclear, and oil at 16%, 13%, and 5% respectively. Of the fuel burned, only 39% went into producing energy and rest was lost as heat. Only 3% of the heat was then used for co-generation. Of the 20,261 TWh produced, 16,430 TWh were delivered to consumers and the rest was used by the plants themselves.

It is clear that a great deal of energy goes into producing electricity, which isn’t surprising given that everything humans do in the industrialized world, from running water to surfing the internet, requires electricity. Most estimates suggest that about 40% of all GHG emissions come from the production of electricity, with transportation coming in a very close second. Coal, in particular, is highly problematic for its production of sulfur dioxide, which produces acid rain. Interestingly, nuclear power is the least damaging in terms of pollutants produced, generating less carbon than any form of power generation other than hydro and including solar (PV panel production uses large amounts of water).

So, if humans are not going to switch to nuclear power, then a cleaner, more renewable form of energy is needed. Biofuels may provide at least a partial answer. Co-generation plants often use methane derived from landfills and there is vigorous interest in the use of syngas in many agricultural areas. Like any biofuel, the balance of the equation lies in carbon generation. For syngas made from the agricultural waste, the net impact is lower than if the waste were allowed to decompose on its own. This is because natural decomposition in oxygen-rich environments produces nitrogen dioxide, with is over 300 times more potent of a greenhouse gas than carbon dioxide, as well as methane, which is over 20 times more potent. The same benefits exist for methane harvested from landfills.

Of course, these applications are not enough to meet our energy needs and so the conversion of crops grown specifically for energy is where most of the research and development is occurring at this stage. Algae and other plants that grown in harsh conditions and thus do not threaten the food supply are actively under investigation for potential sources of biofuel. At this point, only about 13% of all electricity in the United States is made from renewable sources (excluding hydro), but very little of this is biofuel. Most of the electricity from biofuels is produced as a byproduct of fuel production for transportation. The United Kingdom is the largest market for biofuel-to-electricity generation, generating enough power for 350,000 households from landfill gas alone.

Heat

The major use of natural gas from fossil fuels is heat, though a good deal of it also goes to energy. In the United States, a boom in hydraulic fracturing (called Fracking) has led to a huge surge in the production of natural gas from shale (a fossil fuel) and to the prediction that this will soon become the predominant form of energy, perhaps as soon as 2040. Of course, natural gas need not come from fossilized plant material, it can also be produced from recently grown plant material.

Of course, the majority of biofuel used in heating is solid. Wood is both an aesthetic and a practical method of heating and may homes use wood burning stoves as supplements to other heating systems like natural gas or electricity. Renewed interest in solid biofuels, in part a response to rising energy prices, as led to a surge in innovation in the industry with research focusing on improved efficiency, reduced emissions, and enhanced convenience. Wood gasification boilers can reach efficiencies as high as 91%.

To put the cost of biofuel into perspective, 1,000 BTUs of energy from wood cost about $1.20. Natural gas, on the other hand, cost about $2.60 per 1,000 BTUs. Wood pellets cost around $2.16 per 1,000 BTUs, making them less expensive than natural gas as well. The table below shows the cost of various fuels and provides a not on efficiency.

Fuel

Cost per 1,000 BTUs in U.S. Dollars

Energy Efficiency

Heating Oil

$3.17

78%

Natural Gas

$2.60

80%

Wood

$1.20

70-91%

Electricity

$3.22

100% (in home only)

40% (from plant)

Propane

$3.13

78%

Wood Pellets

$2.16

70%

Coal

$1.10

70%