Include:

Text to describe why your team solution is technically feasible, socially and environmentally desirable and economically viable? Say this in 500 words or less.

One of the advantages of using solar energy as an energy source is the fact that it is tried and tested. Most countries in the world actually use solar energy in some way, and this makes our design solution much less risky. The design of the solar panels themselves already exist, and it just a question of finding the right space to accommodate them. Since the task involves a switch-over form motor vehicles to electric vehicles, it means that in theory, the more electric cars we introduce, the less motor cars we have to cater for. As such it is logical to use existing petrol stations as the site for the new charging stations. It also makes sense logistically, being that the current petrol stations are likely to have been strategically built to meet the demand on Singapore road users.

Solar energy also seems more economical than other alternative fuel options. For example, it came out far more expensive to use fuel cells than solar panels. It is also an idea that people are used to, and so it is likely to be more easily accepted, as people wont feel like a 'guinea pig' by jumping on the bandwagon.

It is also a very environmentally friendly way of generating electricity. The sunlight radiation is energy that is coming our way anyway, and if we can use solar panels to channel that radiation into usable energy then we can produce energy while causing close to no damage whatsoever to the environment.

As mentioned before, we try to investigate on solar energy for electric cars charging. The solar collection board will be installed on the roof of existing gas stations. This may take 25% of the total demand and the rest goes to solar power station which is located on an artificial island.

Figure 1. The carbon emission of different kinds of energy sources (Sims et,al. 2003).

In terms of sustainability, our idea is quite satisfying because we plan to use solar energy. According to the definition of sustainability, using solar energy is able to meet the needs of the present demand and will not cause damage further generation. In addition to this, people do not have to worry about when solar energy will run out because it can be regarded as unlimited and it is independent of other countries. Here is a table showing the amount of the carbon emission of each kind of energy. As is shown in the table, solar PV will not release carbon which is totally environmental-friendly.

With regard to location, we plan to install solar collection board on the roof of gas station and add charging columns in it.

Figure 2. The distribution of gas stations in Singapore

(http://www.sgcarmart.com/news/carpark_index.php?LOC=all&TYP=petrol)

The map illustrated above shows that the distribution of gas stations in Singapore. The density of gas stations is quite high in Singapore, there are 187 stations in total (4 companies).If all gas stations are equipped with electric car charging infrastructure, it will be convenient for E-car drivers to travel around.

With respect to feasibility, our idea seems to be OK. However, there are still some problems need to be solved. We mentioned that the coverage of electric car infrastructure can be guaranteed, but charging electric cars is not exactly the same as refueling normal cars. The main difference is that the time taken to fully charge an E-car is much longer, which is about 7 hours to 8 hours (Annex 2010). It might be better to design a charging plus parking system for electric cars due to this reason. Although the charging time can be reduced to 30 minutes by applying ‘super-charging’, it may cause damage to battery which means the cost of maintenance will increase (ibid).

When it comes to efficiency, the conversion rate of solar PV is lower than expectation. The detailed information of this is demonstrated below.

Figure 3. The efficiency of various types of PV solar cell (King and Wettergren.2011).

The maximum of solar PV is 30.3% compared to 40% for fossil fuel. Although the efficiency is acceptable in theory, it means we have to consider building more solar panels in order to meet the demand. The solar panel we plan to use has efficiency of 20%. According to our calculation, we need about 1600000 square meters land. In practice, the actual area of solar power station (located on the island) is 75% of this value because the rest is supplied by the solar collection board on the gas stations.

For the cost issue, the price of solar PV is shown below.

The price of solar panels is reasonable and the overall trend of it is decreasing. According to King and Wettergren(2011),the annual dropping rate of the solar PV expense is about 4.5%.

Even thoug it seems that building solar panels is expensive, it will pay back in about 20 years (King and Wettergren.2011). As a result, it is beneficial to investigate on solar energy in long term.

Reference

King, S. and Wettergren, P. (2011) ‘Feasibility study of renewable energy in Singapore’, KTH industrial engineering and management.

Sims, R.E.H., Rogner, H.H. and Gregory, K. (2003) ‘Carbon emission and mitigation cost comparisons between fossil fuel, nuclear and renewable energy resources for electricity generation’, Energy policy, 32, pp.1315-1326.

http://www.sgcarmart.com/news/carpark_index.php?LOC=all&TYP=petrol

As we made our final decision consists of a combination of two resources to provide power for our electrical car system, we used different techniques, such as mathematical calculation, rigorous analysis, pairwise comparison, and so on. The final decision achieved the five design evaluation criteria we set in the first place in following reason:

1. Sustainability: we defined the concept of sustainability to be using resources to meet our current need without compromising needs of future generation, and indeed, that is exactly the reason we choose solar power. Solar energy is the best resources for meeting the sustainability because it is not going to be used up, it does not produce pollution, and it is safe.
2. Location: we design two types of location: existing petrol station, and an offshore island. The reason existing petrol station is considered is that it has already been designed in places that are very convenient to use, and well spread enough to meet the current need. An offshore island is great to use simply because there is not enough land on the Singapore mainland. Based on calculation, at least one square kilometre space is required to provide enough energy generation. Building inside Singapore mainland will significantly increase the cost in land purchasing. 
3. Feasibility: we consider our design feasible in the different aspects, including feasible cost, technologically feasible, and practically feasible. Cost feasible will be analysed below in the cost section. we consider the design to be technologically feasible because solar panel electricity generation technology has been mature enough to provide both an acceptable cost and stable large-scale working station. Practically feasible is one of our largest concerns; therefore we took care of details such as the spreading of charging station, the cost and energy required is calculated.
4. Efficiency: as we mentioned in the design criteria, for our design, not using solar energy that effectively is not the major problem, since sunlight is coming to the earth anywhere. The major concern is that whether we used the land efficiently. By building solar panel on existing petrol stations, we used the land originally not used; by using an offshore island, we minimised the effect on the already very crowded mainland. Adopting a combination of techniques, we maximise our efficiency.
5. Cost: we believe that the return of investing in solar energy system is attractive and therefore enough funding will be available. It can be calculated (in fourth page, energy model cost analysis) that the overall, solar system per 1m2(including installation) costs around £870, which can generate approx. 330 kWh every year. Suppose charging electrical car costs roughly the same with fuel car (which is around £10 per 100km), implementing solar energy system returns about £110 per year. This is a 12.6% return on investment (ROI), which is 50 times the annual deposit interest rate in Singapore.

Before deciding on the final decision, we also considered another possible plan, which is based on removable battery, we build one or several large solar energy station, change the battery every time it run out of power, and charge them collective in the large station. Finally we gave up on this plan mainly because we consider it to be impractical. There are many kinds of batteries out there, and it is very hard to persuade car company to produce all of their electrical car to be battery removable. Also because more batteries will need to be produced for the replacement, it is not as sustainable and cost effective as our final plan. I will provide a decision matrix in the bottom to show the analysis.