Introduction

Within our project we aim to use regenerative energy sources and carbon dioxide to produce bulk chemicals, e.g isobutanol. This system will be executed in Escherichia coli. An electricity source will be used to generate a current which reduces a mediator. The mediator is taken up by the bacteria where the mediator is oxidized. The energy of this reaction will be further utilized to bind atmospheric carbon dioxide. One of the resulting intermediates is pyruvate. In our project pyruvate will be used to produce isobutanol.

Introduction

Within our project we aim to use regenerative energy sources and carbon dioxide to produce bulk chemicals, e.g isobutanol. This system will be executed in Escherichia coli. An electricity source will be used to generate a current which reduces a mediator. The mediator is taken up by the bacteria where the mediator is oxidized. The energy of this reaction will be further utilized to bind atmospheric carbon dioxide. One of the resulting intermediates is pyruvate. In our project pyruvate will be used to produce isobutanol.

Problem analysis

Our project is engaged in different big problems like global warming, the transport and storage of electricity and the depletion of crude oil. To gain a better overview we generated different problem trees which help to visualize the dimension of these problems (figure 1). Secondly it was interesting to identify following problems ensuing our three basic ideas of electric energy storage, fixation of carbon dioxide and production of isobutanol (figure 2). Finally we build up a tree for problems resulting from our main concept (figure 3). The dimension of resulting problems is quite huge so that we decided to contact different stakeholder and companies who might be able to help us.

fig. 1: Global problems

fig. 2: Project problems

fig. 3: rMFC problems

Application scenarios

fig. 4: Scenario for wind power station

fig. 5: Scenario for cars

The main idea of our project is to store the energy which is produced at times of a day when too much energy is produced. For example there is an energy peak at night at wind parks which cannot be stored efficiently. This leads to our first application (Note for following application figures: yellow means electricity, gray means carbon dioxide, green means isobutanol). We think of combining our production system with a wind engine (figure 4). Energy can be used together with atmospheric carbon dioxide to produce a product which can be transported conventionally. This system is also possible for other energy production sites like hydroelectric power stations or solar energy electric power stations. Additionally we think of fabrication of isobutanol while driving. Organization and functioning is shown in figure 5. Solar panels or the current of the car battery can be used together with the exhaust fumes of the car to produce isobutanol. The isobutanol will be added drop by drop to the fuel to replace the gas. This will increase the range of milage. At the moment we establish a cooperation with car producer companies. This application might be also possible for ships (figure 6) or space stations (figure 7). The NASA already send bacteria to the space to do experiments with them. The advantage for the space station is that the anthropogenically produced carbon dioxide is used together with electricity produced by solar sails to generate a useful product. A third idea would be to mount our project on industrial production sites which could be for example a varnish producer. A main part of varnish is isobutanol. Industrial production leads to fumes where carbon dioxide could be extracted (figure 8). Together with electricity which is produced by solar panels isobutanol will be produced. Now we additionally think of more applications at sites with carbon dioxide excess which could be for example produced by the CCS (Carbon Capture & Storage) technology. This manifold application possibilities lead to many different personas.
The needed changes for our system seems big but to add the system to a wind engine nearly no changes are needed. It is simply possible to settle the production system next to the engines to produce isobutanol. It is also imaginable to integrate the system into the wind engine stem. An application at industrial production sites can be achieved as easy as for the wind engine. By adding a fermenter, containing our modified organisms, on the envelope of a space station it is possible to implement the system. A new construction plan has to be developed for cars or ships because the system has to be integrated into existing parts.

fig. 6: Scenario for ships

fig. 7: Scenario for space stations

fig. 8: Scenario for industry

Product life cycle

We asked ourselves how long our product will be competitive on the free market so we developed a possible life cycle (figure 9). During development of the product the amount of sales is pretty low but increases during the introduction to the market. At this state different car firms include the system into their car body and the amount of sales increases. In the growth phase many car producers sale the system within the cars. Additionally different power engines change their system to the producer system so that the amount of sales increases exponentially. At the stage of saturation the amount of sales decreases slowly. By changing the conventional mobility to electric mobility a strong decrease is perceptible. The invention of nuclear fusion will make our project dispensable for power stations. Storage of energy is not needed anymore but isobutanol will be further needed for varnish. The end of the system will be near if there is no excess of carbon dioxide or if storage of energy is not needed anymore. In contrast it seems that the project will not vanish this fast. A secondary advantage is the modularity of the project which leads to other products.

fig. 9: Product life cycle

Business plan

fig. 10: Continuos fermenter

To supply the system energy is needed. The electricity is always available through generation via regenerative sources like wind, water or sun. The second source, carbon dioxide, is produced at nearly every industrial production site which makes it an ideal source. The initial production of the fermenter is quite expensive but the envelope has a high life period. The needed components are for example glass or acrylic glass for the outer envelope, a control unit (for pH, temperature, agitator, exhaust air, inlet air, ...), a lid with different pins for the control unit, thermometer, etc. To reduce the running costs we think of a continuous fermenting system which increases the application time of the media, the mediator and bacteria (figure 10). It has to be tested how long materials like electrodes can be used before replacement is needed. The bacteria have to be replaced after two or three weeks because they will get in stationary phase and the amount of dead cells will increase which decreases the efficiency. The media with living and dead bacteria which is extracted out of the fermenter has to be sterilized which result in additional costs. Other costs are for assembly costs, recycling costs and maintenance charges. An additional factor for the financial plan is that the system can be applied at any production site or energy source. This means that the transport costs for the final product are very low. The implementation costs for the car industry will be high at the development stage but by maturing the system the costs will decrease. We aim to generate a business plan with an expert.

Risks assessment

Of great interest for an application are the risks. The advantage of our system is that the cells grow in a closed system. This makes it easier to solve biosafety issues. Next to our main project we aim to develop a selection system without antibiotics. The advantage of this is that the resulting product has no traces of antibiotics which is a benefit for many industrial productions. If the strain loses his plasmid it will die because of the missing alanin racemase which produces D-alanin. D-alanin is a key substance for the cell wall of bacteria which they cannot produce in our strain. In addition we implemented a biosafety system which is dependend on rhamnose (figure 11). Without rhamnose the RNase Ba (Barnase [Bacillus amyloliquefaciens]) will be produced in addition to the end of the expression of the alanin racemase. This leads to lysis of the cell wall and degradation of the RNA (figure 12). Our strain is not dangerous in biosecurity terms because it has no pathogenicity. In addition it has no relevant modifications which can be abused.

fig. 11: With L-rhamnose

fig. 12: Without L-rhamnose

To summarize

For the next weeks we aim to contact different firms and stakeholder who should help us to get insights in solving our problems.

• What:
• A biological production of bulk chemicals in three modules. Frist electricity is used for the growth. Secondly carbon dioxide is bound with supplied energy. The third module produces a product like isobutanol with an intermediate of the carbon fixation.
• Why:
• The project addresses several problems. A main problem is the transport and storage of electricity. We aim to convert excess of electricity into isobutanol. The second problem is an increasing amount of carbon dioxide which results in global warming. The target is to use this amount as a useful carbon source. Another problem is the depletion of crude oil which we engage by producing a part of biodiesel.
• Where:
• Energy producing sites: Wind engine, hydroelectric power stations, solar energy power stations, …
• While driving production: Cars, ships, space stations, …
• Product dependent sites: varnish producers, emollient producers, …
• Who:
• Many different stakeholders are engaged by this project. On the one hand there are all car drivers or electricity users. On the other hand there are industrial production site employees
• When:
• The system can be used whenever energy is available.
• How:
• The system can be settled next to wind parcs or mounted on the envelope of a space station
• A new construction plan has to be made for cars