Small electric boats and their influence on the grid

Charging of electric boats will influence the grid. This article is based on a report from Samraiz Khan, research assistant with UiT in Narvik, summer 2019.

Introduction

Norway has 53,199 km long coastline which include islands and fjords as well. which is 126% longer the USA. Country has long tradition of utilizing the rich maritime environment, consisting major activities in commercial shipping, fishing and leisure boats. Because of high incomes due to evenly distributed wealth in the country people can afford to invest in recreational commodities and making investment in boats justifiable. Weather has the greater impact on sales and boating season is not more then five months.  Sales of leisure boats grew significantly from 2001 and peaked in 2007–08. At its peak, Norway was the second largest European market for boats with outboard engines, which is remarkable because only 5 million people inhabit Norway. 25% of Norwegians have access to one or more boats. Before 15 years it was 13%. And most people had some experience before buying the boat. Round about 800,000 small and medium leisure boats are owned by Norwegians as small boats are not needed to be registered so exact estimate cannot be done. The demand of motorboats is in between 12,000 to 15,000 units. Aluminium hulls are also growing in popularity, statistics describe that boats are becoming more expensive and sale from 2001 to 2007 has gone up by 370% and number of boats are up by 240%. Norway is a net importer of leisure boats; dealers, resellers and individual buyers import six boats for every boat that is exported. The total value of the Norwegian leisure boat fleet is around USD 10 billion, according to insurance companies. A 2013 survey on leisure boat use in Norway revealed that 46% of the population used a leisure boat that year. The nature experience was reported to be the most important reason to hit the water (28.9%), followed by relaxation (23.4%), fishing (19.8%), and social interaction (16.6%). Speed and sports only accounted for 3.6%, suggesting that Norwegian boat owners appreciate the slower and quieter side of boating life.

Electric boats

Electric boats are not a new term in the world of electrical engineering. September 1838, witness a first documented launching of an electric boat. It could go at 2.5 km/h by using zinc batteries that had 320 pairs of plates with more than 180 kg. Outboard motor designs that followed later enabled active actions on the commercial production of electric boats. By 1888, Magnus Volk, Immisch & Co.’s fleet of six boats has been deployed along the Thames. Large and heavy DC motors followed in 1905. However, in 1920, efficient internal combustion engines made the popularity of electric boats sharply declines. In the latter decades of the 20th century, Commercial electric boats recorded a precise recovery as The Tûranor Planet Solar is currently the largest solar-powered boat in the world at 31 meters. Electric boats continue to provide a clean and quiet method to traverse the planet’s waterways. Electric boats will be even more critical in the coming years.

Some issues to discuss are the actual costs and cost perceptions, risks, technological conservatism, unfamiliarity, and lack of knowledge.

Table 1 – List of battery-electric ships, charged mainly from shore power [1]

YearNameCountryBattery energy [MWh]Charge power [MW]Charger typeNotes/Ref
2015MF AmpereNorway11.2Cavotech plug
Stemmann pantograph
Car/passenger ferry
2017MF Tycho BraheDenmark/Sweden4.1611Robot plugHH ferry route
2017MF AuroraDenmark/Sweden4.1611Robot plugHH ferry route
2017ElektraFinland1Gravity plufgSimilar to Ampere
2017China2.4Cargo ship

Advantages of electric boats

  • Easier autonomous navigation
  • Quiet operation which gives tours by not disturbing marine life
  • Better acceleration
  • Energy independence by harvesting sun, waves, tide, and wind
  • Lower up-front cost for small vessels and potentially lowest cost of ownership most vessels
  • Environmental benefits: reducing deaths & sickness of humans and wildlife from local air and water pollution.

Things to consider when buying an electric boat

Basic efficiency

  • Inside ignition engine is broadly thought to be about 21% effective.
  • Generally, 80% of the vitality delivered is warmed and is extinguished in smoke.
  • An electric engine can accomplish almost 95% productivity.
  • 95% of the vitality in the battery is transformed into usable movement vitality
  • That is as a rule around multiple times more productive than an interior ignition motor.
  • Electrons are less expensive to disseminate than molecules.
  • Separating, handling, and conveying non-renewable energy sources is expensive and
  • Capacity and recharging of electrons are generally shoddy and proficient.
  • An inward ignition motor and transmission have about 2,000 moving parts:
  • Motor
  • Suppressor and Exhaust
  • Battery Bank
  • Cooling water
  • Shaft, orientation, seals, swagger, and propulsion
  • Starter battery
  • An electric framework can have, probably, around 20 moving parts.
  • Engine
  • Cooling water
  • Shaft, orientation, seals, swagger, and prop
  • Batteries

Annual costs compared to diesel

In the first place, to survey how much strength is required to drive the vessel at ten mph, let us discover the speed-to-length proportion for Dasher, at ten mph, with the body’s waterline length evaluated at 28 ft. (SLR = 10 mph/√28 ft.) . This yields a speed-to-length proportion of 1.89.

To accomplish that speed, we’ll need the correct weight-to-control balance. Utilizing that 1.89 speed-to-length proportions, we know from estimations that for this SLR of 1.89, there must be 167 lbs of the pontoon for each unit of strength. Dasher weighs around 6,500 lbs and that 167 lbs for every hp equivalent 39 hp to drive the pontoon at ten mph.

Here is the fast equation for evaluating fuel utilization: Gallons Per Hour = (Specific fuel utilization x HP)/Fuel exact weight.

For Dasher GPH = (.4 lb/hp x 39 hp)/7.12 lb/gallon = 2.19 gph.

Along these lines, at ten mph, driving 1000 miles will take 100 hrs. At that term, we devour 100 hrs x 2.19 gph = 219 gallons. Accepting diesel fuel costs $3.00 per gallon x 219 gallons.

Diesel’s primary concern: $657 for every 1000 miles.

All-Electric Propulsion

We know from over that 39 hp is expected to drive Dasher at 10 mph. From that, we convert control into kilowatts by isolating by a factor of 1.34. Along these lines, 39 hp/1.34 = 29.1 Kilowatts. Alright, call it 30 Kw for simplicity. Much the same as in diesel control, to run 1000 miles at 10 mph, we need 100 hrs. That way to convey the power required, we need 30 Kw x 100 hrs or 3,000 Kilowatt hours, or Kwh.

The normal expense of electric conveyance broadly is $0.12 per Kwh. Furthermore, disregarding numerous subtleties in misfortune/gains in proficiency and different issues we’re dodging for this representation, we see that $0.12/Kwh x 3,000 Kwh

All-Electric’s primary concern: $360 for each 1,000 miles.

Figure 1 – Overview of electric boat components

Electric boats and their future in Norway

A seagoing nation, Norway has the world’s eighth largest maritime fleet. Norway has built fist electric ferry in the world and first electric fish farm vessel.  And first electric container ship will come home in 2020 as well. All public ferries has low or zero-emission technology since 2015  And, by 2050, the country aims to produce zero greenhouse gas emissions from all its shortsea shipping and sea transport.

Electricity grid

The electric grid is a system of synchronized power suppliers and shoppers that are associated with transmission and circulation lines and worked by at least one control focuses. One person talks about the power “framework,” they’re alluding to the transmission framework for power [2].

Figure 2 – Schematic of electricity grid

What you have in your home is a single-phase power. The rate of wavering for the sine wave is 50 cycles for each second. Oscillating power like this is by, and large alluded to as AC or exchanging current. The option, in contrast to AC, is DC or direct current. Batteries produce DC: A constant flow of electrons streams in a single bearing just, from the negative side to the positive side terminal of the battery.

Large electrical generators in use today happen to produce AC, so transformation to DC would include an additional progression. Transformers must have rotating current to work, and we will see that the power conveyance framework relies upon transformers.

How could electric boats influence the grid?

The market of electric boats is boosting and expected to exceed by 20 billion usd in 2027 worldwide. There are about 100 manufactures of electric boats and motors worldwide. In Norway GMV Grovfjord Mek. Verksted AS, Marex, Saga Boats, Nidelv etc are the players which are producing electric boats and trying to meet the rising demands. With the rising number and demands of electric boats the charging infrastructure is also growing which is often helped by government. But how will the shift of electric boats impact their grid? Are the grids prepared to accommodate this extra load?  What will happen to peak demands? These are some question which are needed to clear[3]:

  • The last mile’ problem
  • The Peak Demand Problem
  • Managed Charging
  • Contributing into the Grid
  • Long-term Threats – Congestion and Exceeded Capacity

The last mile problem

In Norway the increased number of electric boat’s number, puts constraints on current grid capacity. This constraint can slow the slow down the implementation of electric boat technology. At local level in small cities and towns, grid capacity cannot accommodate the boats where numbers of electric boats are high. Local grids are not designed to inhale the sudden and huge spike in power demand.

If I talk about electric fish farm vessel by GMV, it requires 350KWh of energy to be recharged with the charging power of 2x87KW. Comparing this energy with the energy required to charge a normal electrical vehicle which travel 40 km daily (requires 6-8 kWh), then it is 40 times more than the energy required to charge an electrical car.

Residential power transformers are the most effective and vulnerable elements of the system that connect businesses and houses to grid. A typical residential transformer are built to operate between 10 to 100 kVA of load. If we charge our single GMV boat with this transformer, it will consume 87.5 kVA for 4 hours. With multiple boats charging at the same time (this phenomena is called clustering), can damage and cause outage from overloading the transformer. A single overloaded transformer can affect the power quality negatively in other feeders.  As we know that transformers do not have any built in system to send signals about their conditions or health to utilities and power companies, they do not have any way to know about overloading of transformer.

So how this scenario is influencing the grid? Higher number of boats charging at the same time on the same transformer can grow factor called transformer’s loss of life by very high rate. To overcome this problem, high power rated transformers are needed to be installed that is an expensive process. Another way to make things work is, different kind of systems can be introduce to get the information of new boats coming into that area when someone buy new one.

The peak demand problem

What happen when all boats and electric cars are recharging at the same time at evening, when all other houses are also consuming full power while cooking dinner, heating, lighting etc.? In this case, overloading the transformer in not a new thing. Peak hours leads to overloading the transformer, and local transformers cannot stand with this high-power demand.

How could this situation influence the grid, and can it be prevented? Power companies can handle this situation by price. What if companies start giving discounted or lower prices to electric boats and electric cars during the time when power demand is low, or when the production of  renewable energy is high? Boat battery will be charged until morning without effecting the system. Electric boats should come with smart charging where owner plugin the boat and charging starts on the preset time. This scheduling called valley filling where electric boats or electric cars recharge on non-peak demand times. By this way, companies can save lot of money and reduce the load on system. However, valley filling is not the ultimate solution. It has some problems as well. In areas where these kinds of incentives are introduced, will all owners set their timers to start charging when off-peak rates will come to affect producing a new peak demand in power consumption? Charging at night is not necessarily a good solution, because transformers usually cool down at night. Minimizing the cooling time of transformers can produce blackout, as copper windings of transformers will be burned by sustained excess current.

Managed charging

As I discussed in section “The peak demand problem”, power companies can encourage consumers to recharge their boats when surplus renewable energy is present in the system by reducing the price. This can be achieved by managed charging.

This is also known as smart charging and can be done by sending a signal to boat, owner or charger to model the decision of owner to when to charge the boat by a proper system and communication. Right now, this technology in testing process but near to completion. In America, about 69% utilities are considering implementing this system (small electric power alliance 2017 survey data).

How it will work? By a mobile phone app, boat owner will be informed a day ahead about the prices of energy for the whole day. This will not only reduce cost for boats owners, but also minimize the load on peak hours, maximize the consumption of renewable energy and reduce dependence on fossil fuel-powered plants.

Contribution to the grid

Plugin boat typically means consuming energy from the grid, but what if electric boats start discharging? In this way, boat will act as a battery and send power into grid. This phenomenon was first introduced for electric cars and named as vehicle to grid (V2G), but we can use tis for boats as well and can name it boat to grid (B2G).

This way, boat owners can make money as well as charging the batteries on low price through criteria “managed charging” as discussed earlier in this report. Energy and power can be sold to the power grid in high price periods when needed.

Electric boats can contribute in grid stability when sudden disturbance accurse like sudden changes in load, generator tripping or bus fault.

Long term threats congestion and exceeded capacity

Shifting the electric boats load to off peak hours can slow the rate of increasing peak demand and minimize the impact of electric boat adoption. As number of electric boats are increasing, it will eventually increase the peak demand further, which can compromise the reliability of grid. Poor transmission and generation will result blackout. The grid has to manage the sufficient power to charge the boats in congested days. Under current limitations if grid is capable of maintaining the power then it will serve as the limiting factor for the adoption of electric boats. Congestion’s costs are already peaking in transmission lines and will increase more when number of electric boats will increase with the time.

Conclusion

There are unique challenge, but also opportunities for grids because of electric boats. As technology is shifting from fuel to electricity, more production is needed in the energy sector.

The grid can handle the huge production of electricity, but problems at local area will come up. Cluster charging, when lot of electric boats will recharge their batteries at the same time in the same area, posing risks to local system. By building infrastructures to manage local load and static pricing is not the long-term solution and will be less effective in future. Unpredictable load behaviours because electric boats charging will become more complex and difficult to handle and manage.

Smart charging technologies and dynamic price apps are more suitable then others and avoid the production of infrastructures.

References

[1] Wikipedia contributors. (2019, April 22). Electric boat. In Wikipedia, The Free Encyclopedia.    from https://en.wikipedia.org/w/index.php?title=Electric_boat&oldid=893654095

[2] Saurabh Nayar,  M-Tech, Power System@ BIT Mesra from https://www.quora.com/What-is-the-difference-between-a-grid-and-a-substation

[3] E. Schmidt, “The impact of growing electric vehicle adoption on electric utility grids,” [Online]. Available: https://www.fleetcarma.com/impact-growing-electric-vehicle-adoption-electric-utility-grids

Figure 1: https://www.altestore.com/howto/renewable-energy-system-in-your-rv-or-boat-a69/

Figure 2: https://www.electricaltechnology.org/2013/05/comparison-between-ac-and-dc.html

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