Can Biobutanol Made from Palm Waste Save Gasoline Engines in the Electric Car Era?

By Bambang Sutejo Manik, Department of Chemical Engineering, Indonesian Institute of Palm Oil Technology (ITSI), Medan, Indonesia
Special to The Digest

Everyone seems to accept that electric vehicles (EVs) are the golden ticket to an emission-free future. Mass campaigns are being launched, subsidies are being offered and giant battery plants are being built. Yet there is a hidden reality behind the silence of this emission-free and noise-free technology that is not publicly acknowledged that there are hundreds of millions of vehicles driven by internal combustion engines (ICEs) that will continue to operate for years to come as the global stock of electric vehicles (excluding two- and three-wheelers) is only about 80 million vehicles and is expected to increase to 510 million vehicles by 2035. It will take a long time to decommission all these vehicles, changing the entire automotive value chain and building a uniform charging network. 

But the real question is – should we decommission all ICE engines or just change the type of fuel they use?

The illusion of zero emissions in electric vehicles

There is a need to reassess the narrative that electric vehicles are completely emission-free. In developing countries such as Indonesia, electric vehicle operations are largely based on the use of the national power grid, which has a Steam Power Plant (PLTU) as the main source of electricity at 66 percent. Based on the calculation of life cycle assessments in Indonesia, it was found that electric vehicle emissions reached 70,996 kg of carbon dioxide equivalent per 150,000 km traveled, compared to vehicles with conventional internal combustion engines of 60,451 kg. In the absence of a net renewable energy network, electric vehicles only move emissions from exhaust pipes on the road to factory chimneys. However, this calculation is based on several assumptions. A study from ICCT shows that even battery electric vehicles still have the lowest lifecycle emissions in Indonesia. 

In addition, it is difficult to ignore other forms of emissions from battery manufacturing, mining, smelting, refining and nickel produced in Indonesia through the use of coal-fired power plants. Another factor is the use of electricity by data centers which according to the International Energy Agency (IEA) will double by 2030. 

Turning mountains of palm waste into energy

Biobutanol has emerged as a new generation of biofuels with the idea of carbon neutral. The carbon dioxide released when burned in the engine is the carbon dioxide that plants have already absorbed as they grow in the atmosphere. A life cycle analysis  of palm oil-based biobutanol shows that greenhouse gas emissions during the production phase of 5.72 kg CO₂ equivalent/litre can be cut in half by selling excess electricity from the factory to the grid system. In cases where factory generators are fully fueled, such as TKKS, greenhouse gas emissions in the production phase will be reduced to 0.47-0.80 kg CO₂ equivalent/litre due to the same emissions as diesel in the upstream phase. Thus, net emissions can be lower than gasol with combustion phase emissions already included.

The first major benefit of using this fuel is to use lignocellulose biomass waste such as TKKS. Indonesia as the highest producer of palm oil has produced a very large amount of agricultural waste of TKKS which is estimated to be around 15.49 million tons per year and has not been used optimally until now. Using this waste not only serves environmental purposes but also resolves conflicts over land use and food that have been going on for centuries.

Technical advantages as a drop-in fuel

On the other hand, biobutanol has several technical advantages compared to ordinary bioethanol. For example, the energy content of biobutanol is around 29 megajoules/liter, almost the same as the energy content of fossil gasoline, which is 32 megajoules per liter and much higher than bioethanol which is only 19.6 megajoules per liter. In addition, because it has an octane number between 94-96, the fuel does not have high hygroscopic properties, namely it does not absorb water and also does not have steam pressure. The chemical characteristics of biobutanol make it less corrosive and not prone to vapor lock. Therefore, this fuel can be used as a drop-in fuel because it can be mixed with gasoline without the need to change the engine. In the United States, for example, the EPA has approved isobutanol as a gasoline mixture with a proportion of 16 percent based volume.

Real evidence from vehicle performance tests

The reliability of biobutanol has also been proven through various vehicle performance tests both in the laboratory and in the field. In a trial with a 110cc automatic motorcycle, the use of biobutanol by 18% with Pertalite as the fuel resulted in higher engine power and torque due to its perfect combustion process. On the other hand, in a trial of a 4-stroke gasoline engine, the use of biobutanol in an amount of 25-50% reduced carbon monoxide emissions by 27.79-39.11% and hydrocarbon emissions by 15.93-28% from pure gasoline. Biobutanol can also be used to be mixed with diesel fuel. It was found that the addition of small amounts of butanol to the biodiesel-diesel mixture improved thermal efficiency and reduced NOx emissions.

Reducing production costs through technological innovation

Until now, the biggest barrier for biobutanol to be available at every refueling station is its economic value. Based on the results of the technical-economic assessment conducted at the lignocellulosic ABE plant (ethanol, butanol and acetone plant from lignocellulose), the conventional cost of biobutanol production will be at US$2.05 per liter or in Rupiah currency Rp37,000 per liter with an exchange rate of around Rp18,100 per US Dollar. This high cost can be attributed to the biological phenomenon of the inhibitory product in which bacteria (Clostridium) are poisoned and inhibited their growth whenever there is a concentration of up to 13 grams of biobutanol in the fermentation process (13 g/L or 1.3%).

However, there is a way to overcome this economic barrier, namely the application  of In-Situ Product Recovery (ISPR) technology which allows biobutanol to be taken in-situ during the fermentation process. Production costs can be reduced by up to 23% or reduced to US$1.58 per liter (around Rp28,600 per liter). By using TKKS (Palm Shell Scallop) waste which does not require land to grow it, the cost of raw materials is lower. However, the cost is still relatively higher than the price of Pertalite, so biobutanol needs policies and incentives to compete in the renewable fuel market.

Industry synergy and cross-sector collaboration

To realize biobutanol production in an industrial context, synergy between the government, state-owned enterprises and research institutions is needed. State plantation companies such as PT Perkebunan Nusantara together with private plantation companies can maintain consistent performance as basic material providers in the form of TKKS (Waste Oil Palm Processing Mills). Furthermore, the role in bio-refinery and fuel mixing at fuel terminals can be taken over by PT Pertamina through sub-holding, New & Renewable Energy. All of these systems need to be equipped with high-quality bacterial research through BRIN and the allocation of funds for research through BPDPKS.

A realistic bridge to a clean future

Ultimately the energy transition isn’t just about choosing one technology and discarding another. The wrong approach is to compare electric cars to biofuels. Electric cars may be the answer to cities that already have clean electricity systems. But to rapidly reduce emissions from millions of existing motor vehicles, biobutanol derived from palm oil waste could be the most practical bridge. Using agricultural waste as a renewable fuel is the most efficient way to save the world without disrupting the economy.

Category: Thought Leadership