2016/2017 Botswana Energy Update – Part 1 by Mike Mooiman and Karen Giffard

Although I completed my in-country research in Botswana a little over a year ago, I continue my interest and research on Botswana energy matters, keeping in touch with the local energy news and activities of my colleagues working there. However, there is no substitute for being on the ground to fully understand the nuances of the local energy scene so I have drawn on the friendship, experience, and knowledge of Karen Giffard to assist me with my research. Karen lives in Botswana and is an electrical engineer, as well as the co-owner of So Solar, a solar company based in Phakalane, and she is now the very capable co-author of these updates.

We recognize that some of the information we have been able to collect is—as a result of availability and slow reporting—not as current at we would like, but we still feel the collection, analysis, and ready availability of this information, which draws from many sources, is a useful contribution.

In this first post, we take a look at the big picture – overall energy supply and use in Botswana. In an earlier post, information for Botswana’s 2012 energy supply and use was presented in the form of a Sankey flow diagram: below we present an updated version using 2015 data from the International Energy Agency (IEA).

There is a lot of data in this diagram, so let’s work from left to right to get a sense of some of the larger flows. On the left, we have the energy sources for Botswana. There are only four types: local biofuel (wood), imported electricity, locally mined coal, and imported oil products. For 2015, the total energy supply available in Botswana from these sources was 120 138 terajoules (TJ), originating as shown in the pie chart below.

Over one-third of Botswana’s energy supply is in the form of oil products, such as petrol and diesel. The green flows in the Sankey diagram show that these are mainly used in transportation and industry. A small amount was used to generate electricity from the diesel-fired power plants located in Orapa and Matshelagabedi. The small flow to non-energy applications is used largely as lubricants, oils, and greases for industry and transportation. 

As shown by the thick black Sankey flows, Botswana produces and uses a good amount of coal. Most coal is used for the generation of electricity. It is striking to note that only 23% of energy in coal ends up as electricity: the remaining 77% is lost as waste heat. Owing to the increased in-country production of electricity and the coal mining that supports it, coal is now responsible for over 40% of Botswana’s energy supply.

Biofuel (largely wood) is still very important in Botswana: the brown biofuel flows show that all wood is used in household applications, most likely for cooking and heating in the rural and poorer areas.

Electricity supply and use are shown in red. Compared with the 2012 data, which showed that imported electricity was responsible for 12% of Botswana’s energy supply, the amount of imported electricity has decreased markedly and comprised only 5% in 2015. A lot more electricity is being generated locally due to the improved operability of the Morupule B power plant. The bulk of this electricity is used by industry, followed by households, and the commercial and public sectors.

The overall usage of energy by the main categories, as shown on the right of the Sankey chart, is summarized in the pie chart below. The bulk of energy use (41%) is in transportation, followed by households, and then industry, where it is used largely in mining applications.

Botswana’s total energy supply for 2015 was 120 138 TJ, while energy consumption was 81 020 TJ. The large difference between supply and consumption is accounted for by the following reasons:

• More coal was mined than was actually used. Some 12% of mined coal was exported and some ends up in stockpiles to be used in the future.
• Electricity generation in coal-fired power plants is very inefficient. Only about 23% of the energy in coal ends up as electricity. The rest is lost as waste heat.
• Transmission and distribution of electricity to end users results in line losses of up to 15%.
• There are small differences due to statistical variations, own use, and storage of petrol and diesel at various locations.

When we compared the 2012 and 2015 data and Sankey diagrams, we noted the following major differences:

• The amount of electricity generated from locally mined coal has increased markedly, resulting in an increase in coal production;
• There has been an impressive decrease in imported electricity.

For comparative purposes, we have prepared the charts below using IEA data showing the history of energy supply and consumption.

Since 2000, overall energy supply has grown by a compounded rate of 3.2% per year, driven largely by increases in imported oil products (petrol and diesel) and coal mining. Biomass use has been steady. Imported electricity increased and peaked in 2012 and, as noted above, has seen a recent decrease.

Since 2000, energy use has grown by a compounded rate of 2.1% per year, driven largely by increased use in transportation and smaller increases in household and industrial use.

In this post, we have focused on providing a “big picture” view of energy supply and consumption in Botswana. In Part 2, we will turn our attention to specific aspects of the energy situation in Botswana.

In the meantime, remember to turn off the lights when you leave the room. 

Mike Mooiman and Karen Giffard

mooimanm@franklinpierce.edu

karen@sosolar.co.bw

Grid-Connected Solar Energy Projects in Botswana

Dumelang*. In my previous post, I took a good hard look at why there is so little photovoltaic (PV) solar power generation in Botswana and shared with you some of the complexities involved in implementing large-scale solar here. Botswana does have an impressive solar resource, but its exploitation requires a great number of tradeoffs. As a result, there are a limited number of larger-scale solar systems in the country. In this post, I focus on the grid-connected operations. These are systems that feed power back into the grid or that use the electrical grid as a backup, i.e., the grid makes up for any shortfalls in energy generation by the PV unit. I will look at off-grid systems in my next post.

There are presently three large grid-connected systems in Botswana: a single large-scale 1300 kW solar farm in Phakalane to the north of Gaborone; a recently constructed, but not yet operational, 20 kW EU-funded University of Botswana research system installed in Mokolodi village, just south of Gaborone; and a 34 kW system, owned by Scales Associates and located in the Broadhurst area of Gaborone near the Western Bypass. There are a number of other small-scale installations with similar configurations, i.e. grid connected but just using the grid as backup,  that have been installed on residences in Gaborone and surroundings. This post takes a close look at the first two of these grid-connected projects.

   

The Phakalane 1300 kW Solar Power Plant

On the southern outskirts of Phakalane, some 15 km north of the capital, near an industrial area and partially surrounded by undeveloped land, sits the 1300 kW project (see Google Earth view below). The facility is located on 2 hectares and is surrounded by a sturdy fence supplemented with electric fencing and rolls of razor wire and there is a guard permanently on duty at the gate. An informative signboard provides information about the project and a diagram shows the main components.

The project was completed in 2012 and electricity generation started in August that same year. The projected was largely funded by P80 million  from the Japanese government and some contributions from Botswana Power Corporation (BPC) and the Government of Botswana. The total cost of the project was approximately P106 million (approx. US$13.4 million). Even at the time that the facility was built, these project costs were on the high side. Using an average 2012 exchange rate of P7.90/US$, the cost comes to $10.30/watt (W). Average costs for solar projects in other parts of the world were of the order of $3/W at this time. (In 2013 and 2014, utility-scale PV projects in neighboring South Africa were being installed for ~$3/W.)  Now, normally the first major project in any country is an expensive one because everything is new and more ground work has to be undertaken, but a price greater than three times international averages seems exceptional. This most likely contributes to the prevailing perception in Botswana that solar PV is expensive.

The system contains 5920 panels, each with a 220-W DC rating, which gives 1 300 000 W or 1300 kW overall rating. The panels are wired in strings of 16 panels connected in series to provide a peak voltage of 470 V DC. These strings are then combined in parallel with other similar strings and fed into combiner boxes and then into inverters. The electrical output of solar panels is always direct current (DC), but what we transmit over power lines and use in our homes is alternating current (AC), so the function of the inverters is to convert DC to AC. These inverters output 380 V AC, which is then ramped up to 11 000 V through a transformer so that it can be fed directly into the BPC power grid.

I am always impressed that an array of solar panels, each with an output of ~30 V DC can be combined, inverted, and transformed into a grid-compatible AC voltage of 11 000 V. For electric power engineers this is old hat, but I am always impressed. I have visited numerous power plants and am used to seeing large machines thundering away, devouring large quantities of fuel, and spitting out large volumes of waste heat, pollutants, and carbon dioxide to produce electricity. It is a therefore a pleasure to see a field of solar panels, each quietly converting sunlight to electricity and then using technology to configure wiring, inverters, and transformers so that the electricity can be boosted to a form that can be transmitted over the grid and used to power homes in other parts of the country.

In the energy field, one needs to be sure to understand what is meant by the rating of a power plant. Most power plants, say the 600 MW coal-fired operation at Moropule B, refer to their output of AC electricity. In this case, it is easy to calculate how much energy a power plant would generate over a certain time period. For example, if all the generators at Moropule B were running at their rated output, uninterrupted for 24 hours, the output would be:

600 MW x 24 hours = 14 400 MWh = 14 400 000 kWh (1000 kWh = 1MWh)

However, with solar PV operations, the rating is most often given as the combined DC output capacity of the panels under the standard irradiation condition of 1000 W/m² at 25^oC – the conditions known as one peak sun (see an earlier post for an explanation of irradiation and the peak sun hour concept). Although the amount of sunlight in Botswana is high relative to other parts of the world, the irradiation levels are only close to one peak sun at around noontime. A solar panel will therefore only produce its rated output for a short while around midday; the rest of the time, the irradiation is lower and the output is commensurately lower. The figure below shows recent irradiation levels for Gaborone, as measured by a weather station on the roof of the Faculty of Engineering and Technology building at the University of Botswana.

Because irradiation conditions change during the day, we determine the energy that can be potentially harvested in a 24-hour period by calculating the area under the irradiance curve—the yellow area in the figure above. This measure of energy is termed insolation; it is measured in kilowatt hours per square meter (kWh/m²). Another measure of insolation is to calculate how many hours of peak sun (with a fixed irradiance of 1000 W/m²) will deliver the same energy as the sum of the varying (irradiation x time) values over a day. The number of hours of peak sun per day is a particularly useful measure and is extensively used in the solar energy field to determine the daily output of electricity from solar panels. A typical insolation value for the Gaborone area is 6.09 peak sun hours. 

Cloud cover significantly affects the performance of solar panels: the figure below shows the contrast between a day with no cloud cover, February 1,  a day with lots of intermittent cloud cover, February 7 and Jan 14, which was overcast for the whole day: even with just passing clouds, the drop off in irradiation levels is significant.

In addition to a limited number of hours of peak sun per day and cloud cover, there are losses through the electrical system: in the wiring; in the conversion of DC to AC in the inverters; and through the transformers. Losses in PV systems are typically of the order of 20 to 30%.

There are also performance losses due to temperature. Intuitively, one would expect hot sunny days to be ideal for solar power generation, but one aspect of PV technology not often appreciated is that electricity output of PV panels actually decreases as the temperature increases by approximately 0.5%/ ^oC. Solar panels are rated for a temperature of 25^oC. Panels operating in the Gaborone area, where the temperature on a summer’s day can be 35^oC, can expect a 5% decrease in performance. Furthermore, when the clouds roll over the skies during the rainy season, we can also expect a big decrease in electricity production.

The European Commission’s Institute for Energy and Transport (IET)  has developed a great online calculation tool for estimating average losses and outputs for PV systems. One enters the geographic location, the rated power of the installation, and panel orientation and some very useful information on average irradiation, system losses, and PV output are generated. Alongside is the information I generated for the Phakalane location using this calculator.

As can be seen, the average losses were calculated to be 27%, the average daily peak hours were 6.49, and the average output was determined to be 6150 kWh/day, which totals 2240 MWh AC per year. With average systems losses of 27%, the output AC rating of the plant would be 819 kW.

During a recent (January 2016) tour of the plant, I was able to gather some information about its operation. It started up in August 2012 and since then has operated with only four months of downtime (June 2014, July 2014, Dec 2015, and Jan 2016), so the plant has operated for 36 months or 3 years. During this time, the plant has generated a total of 5286 MWh of electricity.

According to the IET calculator, the total electricity output over this time period should have been 3 years x 2240 MWh/yr = 6720 MWh, which means the plant has generated 79% of its expected output. The differences are due to: 1) lower solar irradiation levels during this period – data from the monitoring equipment at the Phakalane plant indicated average monthly irradiation levels of 161 kWh/m² – rather than the 197 kWh/m² used in the calculator; 2) the effects of cement dust from a nearby brick plant coating the panels and reducing their efficiency; and 3) a higher-than-estimated temperature effect on the panels. It always astounds me how hot solar panels get when they are exposed to sunlight: surface temperatures of solar modules can rise to greater than 70^oC – much higher than ambient temperatures. At 70^oC and with −0.5 %/^oC performance losses, decreases in performance can reach as much as 23% at certain times during the day.

Another useful calculation is to determine the capacity factor, which is a measure of the proportion of its maximum output that a power plant actually delivers over a year. A capacity factor of 100% assumes that a power plant runs for 24 hours a day, 365 days a year. Coal-fired power plants have capacity factors of about 60%, nuclear plants 90%, wind plants about 35%, and solar PV plants are usually of the order of 26%. If we assume that the Phakalane plant has an output of 819 kW (assuming 27% system losses), we can calculate that over three years of operation:

Capacity Factor = 5 285 860 kWh / (3 yr x 365 d/yr x 24 h/d x 819 kW) = 24.6 %

This is in line with that expected for solar PV operations.

The Phakalane project is a well-designed operation and, like other PV plants, requires relatively little in the way of maintenance and operating costs. Costs include some electrical component maintenance, security services, cutting back of vegetation and weeds so that panels don’t get shaded, and the occasional washing of the panels. Unfortunately, it is located near a cement and brick factory and, as a result, there is a carryover of fine cement dust that settles on and coats the panels, especially those closer to the factory: a fair amount of effort is required to remove the encrusted coating on these panels.

The single biggest challenge for the Phakalane plant is vandalism and panel theft. There was recently intrusion at the site and large amounts of grounding cables were stolen for their copper value. Six panels were also stolen, despite the installation of special anti-theft fasteners on the panel attachments. As noted previously, the facility has been down since December 2015 and during my tour in mid-January I noted that repairs were underway. Hopefully the plant will be operational again before long.

As solar installations proliferate, panel theft is becoming a growing problem worldwide. Many installations are located in remote areas with limited security, so it is often easy for thieves to access the area and take their time to unbolt and load up the panels. Added to this, solar panel installations have large amounts of grounding wires, making them an inviting target for thieves who are looking to steal copper wire that can be sold to unscrupulous scrap dealers.

University of Botswana’s Mokolodi Village Project

To the south of Gaborone, and bordering the Mokolodi Game Reserve, is the small village of Mokolodi, which is home to about 600 people. This is a relatively new village by Botswanan standards and is surrounded by large properties and some high-end housing developments. Right in the heart of this village, the Clean Energy Research Centre at the University of Botswana has built, using money from an EU grant channeled through the African Union, a small, but in the history of solar power in Botswana—an important solar PV installation.

This will be the first of its type in Botswana to feed electricity produced in excess of that used onsite into the local low-voltage grid at 400 V. Phakalane is also a grid-scale project, but it is designed to feed all of its produced electricity into the high-voltage section of the national grid, whereas Mokolodi is designed first for local energy use and then for directing excess energy into the grid. It is important to appreciate that feeding excess solar power onto a grid is not a cutting-edge concept: in fact, it is the basis for most smaller solar projects installed in the US and Europe during the past decade or so. These systems are designed to generate electricity during the day to power the home or business; any excess generated is fed back into the grid and electricity is drawn back from the grid during the night hours as needed. Most of these systems are not designed with battery storage, so they are not self-contained off-grid systems: the grid is their backup system and they are very dependent on the grid to compensate for electricity needs at nighttime or for shortfalls during cloudy days.Another important aspect of these types of systems is that they are not a buffer against the effects of load shedding or other grid interruptions: when the grid goes down, they are designed to switch off immediately. This is to avoid little islands of solar electricity generation feeding electricity into a dormant grid and that could pose an electrical safety hazard for any electrical line workers who might be repairing lines in the area.

The Mokolodi system has a rating of 20 kW and, because it is an experimental system, consists of the following components:

• A 5 kW system on the village clinic to provide daytime power for the clinic and to feed excess electricity into the grid;
•  A 2 kW system on the home of the village Chief to provide daytime power and to feed excess electricity into the grid during the day;
•  A 10 kW system at the Kgotla (meeting place), designed to power the Kgotla and some Village Development Committee owned homes during the day, with any excess fed into the grid;
• A 3 kW experimental system that consists of three different types of silicon-based panels that their performance can be compared and contrasted;
•  A small weather station to measure the solar irradiation, temperatures, and wind speed.

One of the more interesting aspects of this project is the direct comparison of the performance of the three types of panels (1 kW of monocrystalline silicon panels, 1 kW of polycrystalline panels, and 1 kW of amorphous silicon panels) under the energetic and harsh Botswana sunlight. UB researchers will be able to monitor their performances over the short and long term to determine which would be best for the high irradiation conditions here. The photographs below show some views of the Mokolodi project. 

13 kW University of Botswana Solar Installation at Mokolodi Kgotla

Once the project is up and running, the UB team is hopeful that the project will provide the following benefits:

•  There are presently several non-electrified homes not connected to the grid. These homes will receive “free” solar power from the grid during the day; at night, they will draw power from the grid and pay normal BPC rates.
• This is a demonstration installation for similar low-voltage grid-connected projects. It will allow BPC and the UB team to gather information and experience and open the way for the installation of similar systems throughout Botswana.
• The generation of any extra power will be feed into the grid at no cost to BPC and, in a very small way, reduce the amount of coal that needs to be burnt.
• It will be a valuable research tool for UB and its students and will allow the in-depth investigation of small-scale solar systems and their variability, their impact on the grid, and the performance of different panel types.

The UB team at the Clean Energy Research Centre will also be investigating the socioeconomic benefits to communities of free solar energy during the day and purchased electricity at night. The project is close to completion and hopefully will be commissioned in the near future. As the project moves forward and starts generating research results, I hope to share some details in a future blog.

This post has taken an in depth look at two important grid-connected PV systems in Botswana and in the next, I will be discussing the far more numerous off-grid systems that are scattered throughout the country. In the meantime, look out for solar projects and remember to turn off the lights when you leave the room.

Tsamayang Sentle**

Mike Mooiman

mooimanm@franklinpierce.edu

Click here to be notified of new Energy in Botswana blogposts.

(*Greetings in Setswana)

(**Go well or Goodbye in Setswana)

Under Pressure – Botswana’s Coal Energy Resources

Dumelang*. As I have been reading the local press, internet articles and other literature, I was surprised at the number of coal-based projects that have been proposed for Botswana over the years. I was having trouble keeping them all straight so I decided to collect, summarize, and tabulate these coal projects. At the same time, I wanted to take a hard look at coal as an energy resource.

It is generally believed that Botswana has significant coal resources and it is clear, based on the existing, planned, and proposed projects listed in the table in the Coal Projects in Botswana tab on this blog, that coal will continue to be an important resource for Botswana well into the future. These projects range from the new coal-fired generators at Morupule, the refurbishment of the Morupule A operation, new coal-fired operations, coal-bed methane, coal-to-liquid projects, and new mining operations.

A number of years ago there was a flurry of project proposals to start up new coal mines and to build new power plants on-site or close to these collieries to feed electricity into the Southern African Power Pool. However, since the construction and partial commissioning of the large Kusile (4800 MW) and Medupi (4800 MW) coal-fired projects in South Africa, in combination with load shedding, efficiency drives, and renewable energy projects, there appears to be less call for smaller independent coal-fired power plants. Few, if any, of these smaller projects have gained traction.

The list of coal projects proposed for Botswana is long. (See the Coal Projects in Botswana tab on this blog.) Most of the projects are at varying stages of preliminary assessment—some are still under review, some have completed detailed feasibility studies, and some are just proposals—but most are currently on hold because of the large capital investments required and low coal prices. Moreover, many of the projects have been suspended because they are export-market driven and require the establishment of railroad infrastructure to Namibia or Mozambique to deliver coal to the international markets.

Coal is a troublesome energy resource. It is cheap and readily available. One tonne of coal, which costs about $50 on the world market, contains 24 000 MJ of energy—or approximately four times that of a $50 barrel of oil. Despite its high energy content, coal needs to be converted into another energy form to be useful: this could be as electricity or, in the case of the Sasol operations in South Africa, into liquid hydrocarbon fuels.

The ready availability and high energy content of coal is offset by the high levels of pollution associated with its use. Coal consists largely of carbon, as well as varying amounts of hydrogen, oxygen, nitrogen, and sulfur. Coal used for electricity generation normally has a carbon content greater than 75% and also contains compounds of aluminum, calcium, and silicon that form ash when the coal is combusted. Coal is also contaminated with deleterious metals, such as cadmium, mercury, selenium, lead, and others. The key problem associated with coal is that, on burning, it releases these nasty elements, as well as fine particulate matter, sulfur dioxide, nitrogen oxides, and carbon dioxide: these all end up in the off-gases and are released into the environment. Some coal plants incorporate expensive particulate-capture and gas-scrubbing units to reduce the emissions, but considerable quantities of these pollutants are still released into the atmosphere. In terms of greenhouse gases and increasing levels of carbon dioxide in the atmosphere, coal is particularly bad and coal-fired electricity is the largest contributor to man-made carbon dioxide emissions.

Coal or fly ash is another problematic byproduct of coal combustion. This consists largely of a fine, non-combustible silica and calcium oxide residue and can contain appreciable amounts of deleterious elements like cadmium, chromium, and others. The ash is stored on-site at power plants or is disposed of in landfills. In some cases, it can be used as a component of Portland cement.

It is all these nasty byproducts (deleterious metals, coal ash, carbon dioxide, fine particulates, and sulfur dioxide) that are behind the widely accepted assertion that coal is a dirty fuel…And this does not even begin to consider the issues associated with coal mining—which is a dangerous, difficult, and complex operation that has significant environmental impacts. Mined coal cannot just be used as is: it needs to be treated through various mineral-processing operations to upgrade its quality and reduce the portion of non-coal components. This beneficiation requires water and also produces a significant quantity of byproducts – known as middlings and discards. These byproducts can represent up to 50% of the mined ore and are typically accumulated on site at the colliery and stored indefinitely. Moreover, the sulfur in this mining waste reacts with air and water to form sulfuric acid which leads to acidic runoff, known as acid mine drainage, which, if not controlled, can contaminate local water supplies.

In a future post, I will take a look at “clean coal” and the many options available to mitigate the harmful effects of coal combustion. Each of these approaches has pros and cons, but in every case there is a significant economic penalty to be paid. As a result, promoting coal projects with state-of-the-art clean coal and pollution control installations requires enormous political will, stringent regulations, and the willingness to take on increased capital and operating costs—which will ultimately result in higher electricity costs. This is a price that many less developed countries are simply not in a position to pay.

When I cover coal as an energy source with my MBA students in the Energy and Sustainability track at Franklin Pierce University, I have them consider the entire value and utilization chain associated with coal, along with its inputs and outputs, so that they can appreciate the complexity and implications of the coal-fired electricity business. A summary of this value chain is reproduced below. As can be seen, the coal-fired electricity business is complicated, with several energy, water, and labor inputs and numerous outputs that have significant impacts on the environment. All of these energy and water inputs and the polluting and harmful outputs need to weighed against the benefits of useful electricity generation—without which our modern lives would not be possible.

Despite these drawbacks, coal will continue to be a very important fuel for a very long time all around the world. Some countries are moving away from coal and closing down aging coal plants, but these countries possess alternative sources of energy, such as those of natural gas and nuclear reactors, and, in some cases, renewable energy from solar and wind. These alternatives are not options for less developed countries like India, China, and much of Africa at present: coal will continue to be a very important part of the energy supply in these countries, regardless of the long-term environmental impacts. Ideally, one would like all coal-related projects to carefully evaluate the long-term environmental impacts of coal mining and coal burning against the immediate benefits of electricity production, but, unfortunately, this is (for various reasons) not always done.

Exploiting the coal resources in Botswana is a challenging endeavor. Mining is straightforward, but, once mined, the coal becomes a stranded resource. It is difficult to export due to the lack of direct rail links to the port of Walvis Bay in Namibia or to Mozambique via Zimbabwe, and there is limited rail traffic to Richards Bay in South Africa. Moreover, exporters of Botswana coal have to compete against large established coal mines in South Africa that have better access to transportation and export networks. There have been several proposals to build rail links to Namibia or Mozambique, but, owing to the cost of these rail links and low prices for coal, there has been little progress of these beyond the discussion stage.

The world is presently awash in coal: demand in countries such as the US and China is down; there is an excess of supply from coal-exporting countries like the United States, Australia, and Indonesia; so coal prices are depressed. The figure below shows spikes in coal prices in 2008 and 2011, which drove a lot of the interest in coal mining and coal-based projects. Since then, however, prices have fallen off considerably and are currently the lowest they have been in the last 10 years.

Source: InfoMine**

The exploitation of coal resources in Botswana is further complicated by the present water crisis in the country. As shown in the value chain above, coal mining and electricity generation require a great deal of water: any coal-related projects need to ensure a steady supply of water in the face of challenging shortages in the country.

Overall, coal exploitation in Botswana can be viewed as being under pressure from five directions, as shown in the figure below: 1) capital investment, 2) coal prices, 3) water resources, 4) environmental impact and increasingly stringent legislation, and 5) lack of transport infrastructure. Pressure can be relieved, to a degree, by exploiting these resources internally, such as by building more in-country power plants and perhaps even coal-to-liquid operations. Even so, such projects need large capital investments, large water requirements, and will still have significant environmental impacts. The successful exploitation of coal in Botswana will require dealing with all of these factors.

In my next blog, I will take a closer look at coal projects that do not involve the generation of electricity, particularly those involving coal-bed methane and coal-to-liquid production. Until next time, remember to turn the lights out when you leave the room so that less coal has to be burnt.

Tsamayang Sentle***

Mike Mooiman

mooimanm@franklinpierce.edu

Click here to be notified of new Energy in Botswana blogposts.

(*Greetings in Setswana)

(**Coal pricing is complicated: it depends on source and destination locations, quality, ransportation, and a host of other factors, so I have just used the North American Central Appalachian price (CAPP) as a proxy for international coal prices.)

(***Go well or Goodbye in Setswana)

The Big Picture – Energy Supply and Consumption in Botswana

Dumelang.* The best way to approach most country- or statewide energy considerations is to understand the big energy flow picture. To do so, we use Sankey, or flow, diagrams which are often used in the energy industry, an example of which is shown below. In these diagrams the magnitude of the flow of energy is indicated by the width of the arrow. These diagrams were first used in the energy field by an Irish engineer and captain in the British army, Matthew Henry Phineas Riall Sankey, in 1898, to illustrate energy flows in steam engines. The modern version below neatly shows how input energy into a steam engine, in the red flows, is lost to smoke, friction, and heat loss via the steam condensor. Useful energy as forward motion of the steam engine, a small recirculating flow of energy that comes from the recirculated condensed water and a small amount going to the alternators are shown as the blue flows.

The great thing about Sankey diagrams is that they are not restricted to energy flows. They can be applied to quantities of many types. For example, material and cost flows are often depicted. One of the most famous of these flow diagrams is that prepared by the French engineer, George Charles Minard, in 1869, and shown below. This illustrates the fate of Napoleon's army in 1812 – 1813 as they progressed through their disastrous Russian invasion. The width of the lines shows the fate of the invading army. Napoleon crossed into Russian with 422,000 men and, through attrition, minor skirmishes, and some great battles, he entered a largely abandoned Moscow with about 100,000 men under his command. He then turned back to return to France: on the way back, starvation, battles, and incessant harassment by guerilla forces decimated his army to 10,000 survivors. The harsh winter also took its toll on his men - the line graph below the flow diagram shows the decreasing temperatures encountered on the army's return from Moscow. The diminishing width of the flow is a skillful, albeit harrowing, representation of what was happening to the army in the field, the prisoners that were taken, and the lives that were lost. 

  

But I digress… Let's return to energy flows. I have prepared the following Sankey diagram for energy flows in Botswana, based on 2012 data from the International Energy Agency (IEA). The IEA have prepared Sankey diagrams for most countries in the world (including Botswana), and, although this is a wonderful source of data, their flow diagrams are two-part figures showing a complicated spaghetti of flows. I have taken their data and distilled it down to the more easily understood diagram shown below.

Although I am highly impressed with the data that the IEA has collected for most of the world’s countries, we need to be cautious about some of the numbers. In my previous post, I pointed out some discrepancies regarding biofuel usage. I am, as yet, not in a position to verify all the Botswana-related data that the IEA has collected, but I hope to do so over the next year.

There is a lot of data incorporated into this diagram, so let’s work from left to right to get a sense of some of the larger flows. On the left, we have the energy sources for Botswana. There are only four types: local biofuel (wood), imported electricity, locally mined coal, and imported oil products. For 2012, the total energy supply available in Botswana was 109,165 terajoules (TJ), as shown in the pie chart below.

Almost one half of Botswana’s energy supply is in the form of oil products, such as petrol and diesel. The green flows in the Sankey diagram show that these are mainly used in transportation and industry. The small flow to non-energy applications show use largely as lubricants, oils and greases, for industry and transportation.  Biofuel, largely wood, is still very important in Botswana: the brown biofuel flows show that all wood is used in household applications, most likely for cooking and heating in the rural and poorer areas.

As shown by the black Sankey flows, Botswana produces a good amount of coal. Much of this was stockpiled in 2012, but a fair quantity was used by industry and about 11% was used for electricity generation at Botswana’s only coal-fired station, Morupule, which is near the town of Palapye. However, Botswana does not generate sufficient electricity for its own needs. If we refer to the center of the Sankey chart and we follow the red flows, we can see that, in 2012, Botswana only produced a small portion, 7%, of its domestic energy needs. The bulk of its electricity was imported from the Southern African Power Pool grid and came from Mozambique and South Africa. The bulk of this electricity is used by industry, followed by households, and the commercial and public sector.

In my last post I noted that energy consumption for 2012 was 86,206 TJ. The large difference between the 109,165 TJ of supply and the 86,206 TJ of consumptions accounted for by several reasons:

• More coal was mined than was actually used. The difference ends up in stockpiles to be used in the future.
• Electricity generation in coal-fired power plants is very inefficient. Only about 23% of the energy in coal ends up as electricity.  
• Transmission and distribution of electricity to end users results in line losses of the order of 8 to 10%.
• There are small differences due to statistical variations, own use, and storage of petrol and diesel at various locations.

The overall usages of energy by the main categories, as shown on the right of the Sankey chart and the pie chart below are split as follows: transportation uses just over one-third, followed by households, and then industrial use.

So here you have the overall energy picture for the country of Botswana, at least for 2012.  It will interesting to see over the next year or so, as I collect current data, how much this picture will change.

Until next time, feel free to comment on my post and remember to turn off the lights when you leave the room.

Tsamayang Sentle**

Mike Mooiman

mooimanm@franklinpierce.edu

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(*Greetings in Setswana)

(**Go well or Goodbye in Setswana)