ENERGY TRANSITIONS FOR MAURITIUS, FROM NOW TO 2050 : An overview – Part 2 – Heat and Electricity Generation

We find it very common for people and even experts to address only electricity generation when referring to energy transitions, whilst being oblivious to heat and especially transport energy. It is a lopsided approach to energy transition.

Heat Generation

Energy is used to heat water or other fluids and for cooking purposes in domestic, commercial and industrial settings. In Mauritius, space heating of buildings is unnecessary and space cooling is done via electricity. The sources of heat energy can be liquid petroleum gas (LPG), electricity and coal from non-renewable sources. Renewable heat energy comes from solar, bagasse, fuel wood and charcoal. Currently, only about 22% of the heat energy consumed is renewable and all of it is biomass. There are no estimates for the amount of solar energy used for heating purposes in Mauritius. Maybe it is time for Statistics Mauritius to make such calculations and amend its otherwise excellent publications. Solar water heating is a well-established technology that is well disseminated here for domestic purposes but there is probably scope for further use. In some industries solar water heating is used and most probably that can be extended significantly too. For cooking purposes, solar cooking technologies can be used and could displace to some extent the use of LPG. The use of biomass can be sustainable and renewable if the resource is carefully managed. In brief, for Mauritius it is certainly possible to increase the proportion of renewable energy for heat generation. However, it is difficult to estimate how much of it can be shifted to renewable energies. It is thus reasonable to expect LPG to remain important for that sector.

Electricity Generation

Much has been said over the years concerning transition to renewable energies for electricity generation. For Mauritius, our renewable options include solar photovoltaic, wind (onshore and offshore), biomass, hydropower, and wave and sea current energy. Geothermal may be too expensive. The main barriers for penetration of renewable energies are prices and intermittency. Costs of renewable energy equipment have tumbled down over the years and price differentials between renewable electricity and non-renewable electricity have narrowed down significantly. We do expect price differentials to become a fairly minor issue now in investment decisions.

The other barrier is intermittency of renewable sources like solar and wind. There are broadly speaking two ways of tackling this issue which are actually complementary. Firstly, excess renewable electricity can be stored in industrial battery parks and re-injected in the grid on demand. These facilities already exist across the world. Initially costs were high, but once more prices have gone down. Other technologies can be used: for instance hydro-pump storage. It is an old and proven technology, first used in Switzerland at the beginning of the 20th century to store excess electricity generated from hydro-power stations driven by melting glaciers in summer. Very briefly, excess electricity is used to pump water in storage tanks or lakes in altitude and when required this water is used to drive turbines to generate electricity.

Another way to tackle intermittency is to couple renewable electricity with natural gas electricity generation. Natural gas turbines can generate electric power in a very flexible manner, on demand. This flexibility can be used to accommodate the inherent variations in renewable energies. In the equation we should not forget demand side management. It is certainly possible to mitigate demand via some common sense and the use of energy efficient lights and appliances. Current efforts in that direction must continue.

The different modes of electrical power storage with natural gas turbines and demand side management can certainly resolve intermittency of renewable energies thus enabling transition. Certainly, the introduction of natural gas in Mauritius will require careful study. The Central Electricity Board (CEB) had initiated such studies which appear not to have been made public.

Currently, only 23% of electrical power comes from renewable sources, of this 75% comes from bagasse, 18% from hydropower and about 7% from solar, wind and landfill gas. It might be possible to modestly increase power from bagasse or hydro, but it is clear that large increase in solar and wind power or from other renewable sources shall be needed. Alas, solar and wind generated only 29 GWh out of the 2996 GWh produced in the whole country in 2015. Barely 1% of electrical power demand. Should Mauritius embark on a transition to renewable energies for electricity, how fast could this transition take place?

To answer this question we have made a straightforward mathematical model of power demand versus renewable electricity supply increases from 2015 onwards. We then calculated the proportion of our electricity demand that could come from renewable sources by 2035 and 2050. We have assumed a 3% yearly increase in power demand.

Percentage of electricity demand met by renewable energies
 
Year
2035
2050
10% annual increase in RE
17%
18%
20% annual increase in RE
34%
200%

From the above, it is clear that even with an annual increase of 20% in renewable electricity, by 2035 the country shall still have to rely considerably on fossil fuels for 66% of its power demand! A mere 3% yearly increase in power demand can absorb all increases in renewable electricity running at 10% annually. The importance of demand side management is clearly established. Furthermore, we can provisionally conclude that our dependency on fossil fuels will remain more or less unabated at least until 2035.

The question that arises now is what type of fossil fuels should we principally rely on for electricity generation? Should we rely on coal, heavy fuel oil or natural gas? We believe that the country should introduce natural gas and phase out coal and heavy fuel oil as it will reduce pollution significantly given that the burning of natural gas generates very little residues, ashes or noxious fumes and releases only carbon dioxide and water vapour.

Furthermore, worldwide, sources of natural gas are still abundant and plentiful, any peaks in natural gas production are still several decades into the future. The transportation of natural gas is via pipelines or specialized transport ships that do not rely on oil. It is interesting to note that over the past decade large resources of natural gas have been discovered in Mozambique and Tanzania. Both countries should begin export fairly soon. Natural gas sourced in the region will boost trade significantly for it will open up new business opportunities between Mauritius and those countries.

To conclude Part 2, we can say that although an energy transition for electricity is feasible the time required can easily run into decades.  In Part 3 we shall tackle the vexing issue of energy transition and transport.