No two cities are alike. But, they often share similar challenges. It is therefore becoming increasingly important to propose common concepts in a “city context”. Traditionally, we have focused on the bus and its impact. Going forward, the imperative would be to look holistically, into areas such as synergies between clean energy and waste management. The idea is to deliver energy sustainability without taking more out of depleting fossil fuels and food production.
Volvo and Siemens Industrial Turbomachinery AB have jointly researched a novel concept for smart cities over the last 6 months. On May 2, for the first time, Bengt Gudmundsson (Siemens) and I presented the concept of “Smart Gas” at the ‘India Unlimited’ Seminar organized by the Indian Embassy in Sweden along with some partners.
We feel that we have found a beautiful concept to improve quality of living in cities:
- Wastes and sewage is an increasingly sanitary issue. Cities need to find methods to reuse wastes in efficient ways. By fermentation, wastes are converted to biogas and the remains become nitrogen rich fertilizer meant for agriculture.
- Congestion is and increasingly an issue that amplifies the negative impacts of cars. Cities need to provide public transport alternatives that can compete with private cars when it comes to comfort and convenience for citizens. The new generation of fast charged electric buses have what it takes to attract car users. The eco-friendliness and ability to climb in steep inclinations (in contrary to rail bound alternatives) allows buses to use compact cost efficient tunnels to pass under congested crossings. Or why not run in metro-style tunnels in parts of the cities?
- Air quality is improved radically by extremely low emissions at the power plant. The contribution to city smog becomes 100 times less than today and no emissions are let out in the air close to the travelers.
- Noise is reduced by a great extent. This allows public transport to more effectively access residential districts.
- Modern living in cities includes climate controlled apartments. Unfortunately, most commonly, apartments are equipped with small inefficient Air Conditioning units, frequently placed on the façade of the building facing sunlight. District cooling can increase efficiencies and bring forward astonishing energy synergies with gas turbine power generation.
- Electric Power supply is a growing concern in most cities. Electrified transport solutions mostly become a strain for the electric grid. The smart gas concept is different. Firstly, it provides energy to the grid with very high energy efficiency. Secondly, the energy storage of the buses allows for smart grid controls. The smart charging station can allow the grid to ramp-up or down charging second-by-second to compensate for other loads in the grid.
What is Smart Gas?
- As a first step biogas is produced from wastes.
- Delhi, India for example produces, 11,558 tons of wastes that generates about 500 tons of biogas.
- Wastes from agriculture can just as well be fed to the biogas production plant.
- As a byproduct from the bio gas production there is an equivalent amount, 500 tons, of bio fertilizer.
- If it were to be required, natural gas can back up biogas production.
- The enriched biogas can be used as fuel for a combined cycle power plant to generate both electricity and district cooling with a total efficiency of 87 percent. The electric power generated from 500 tons of biogas at an ambient temperature of 30C is 130 MW and the district cooling power is 120 MW. The ratio between generation of electric power and cooling can be optimized depending on the specific requirements.
- District cooling can be used for any housing cooling purpose. If applied to apartments it is sufficient to cool 3,50 000 apartments of 100 m2.
- The 130 MW electricity generated by the biogas can be used to drive 20 000 Volvo electric buses.
- That means the Smart Gas electricity can drive four times as many buses or correspondingly longer distances for the same number of buses as compared to a situation where bio gas is directly used to drive buses.
- An air conditioned electric bus in Delhi will use 1.8 kWh electricity per km while the corresponding gas bus uses 7 kWh CNG per kilometer.
- Each bus has an energy storage battery of at least 75 kWh.
- This opens up endless opportunities for smart grids
- The bus can be connected to the grid over night or be charged at terminals while waiting for passengers
- The on-board energy buffer and a variable charge power of 0 to 300 kW allows us to charge the bus with suitable power that the grid can provide.
We have demonstrated the undoubted gains of the novel concept of Smart Gas from wastes to smart grids, electric buses and district cooling.
But, how about city smog?
Today exhaust gases from buses are let out on in the street level. In the graph to the left we compare emissions of the most modern Euro VI buses with the Smart Gas bus.
If that is not striking enough, we should see the comparison with the existing gas bus fleet in Delhi. The gains are at least fivefold higher!