Geothermal Renewable Energy in Vietnam: A Current Status Overview and Proposing Solutions for Development45242

Geothermal Renewable Energy in Vietnam: A Current Status Overview and Proposing Solutions for Development Van Hiep Hoang 1,* , Van Tich Vu 1 , Trong Thang Tran 2 , Xuan Anh Pham 3 , Tha

Geothermal Renewable Energy in Vietnam: A

Current Status Overview and Proposing Solutions for Development

Van Hiep Hoang (1),(*) , Van Tich Vu (1) , Trong Thang Tran (2) , Xuan Anh Pham (3) , Thanh Tung Phan (1)

(1) VNU University of Science, Vietnam National University, Hanoi, Vietnam

(2) Vietnam Institute of Geosciences and Mineral Resources, Hanoi, Vietnam

(3) Vietnam Oil and Gas Group (Petrovietnam), Hanoi, Vietnam

* Correspondence: hiephv@hus.edu.vn

Abstract: Climate change and energy are two of the biggest challenges in the world and Vietnam

today To resolve the mentioned above problem, especially the energy shortage, studying renewable energy systems is becoming necessary This paper investigates the current status of renewable geothermal energy in Vietnam This study focuses on determining the heat source based on geo-thermometric calculations of K+ - Na+ cations from thermal water in the most 18 potential geothermal sources (in the northern part of Vietnam) in combination with the assessment of groundwater potential by the hydrogeological survey With the deep temperatures of reservoirs are varied from

136oC to 170oC, these geothermal resources can be developed for electricity generation of the capacities from 4.2 MWe to 17.4 MWe Total electric generation capacity from 18 geothermal prospects is estimated to be about 170 MWe Furthermore, the comparison of the policy towards

renewable energy and people’s feedback is illustrated

Keywords: geothermal energy, renewable energy, Natural resources, Vietnam, development

barriers

1 Introduction

Geothermal energy - clean and renewable energy comes from the natural heat of the Earth, primarily due to the decay of the naturally radioactive isotopes of uranium, thorium, and potassium (sometimes caused by geological processes or geological phenomenon) On average, the temperature of the Earth increases with depth, about 25oC - 30oC/km above the surface ambient temperature, and the temperature of the earth at 10 km would be over

300°C In the bottom of the continental crust, it is proved that temperatures are to range from 200oC to 1000oC, and the heat is transferred towards the surface mostly by conduction

In some areas, the heat flows more easily to the surface, due among others, to intrusion of molten magma from depth, to high surface heat flow due to a thin crust, or to the ascent of groundwater that has been heated

Generally, geothermal resources gained above 150oC are produced on electric power generation, the resources have temperature below 150oC are usually used directly in heating and cooling Temperatures from 5oC to 30oC can be used for heat pumps purpose provided both heating and cooling

The thermal energy is the immense amount in the world, but only a fraction of it can

be utilized in areas where geological conditions permit a carrier (such as water), to ‘transfer’ the heat from deep hot zones to or near the surface, thus creating geothermal resources Geothermal production wells are commonly more than 2 km deep, but rarely much more

than 3 km, and most geothermal exploration targets focus on the area where the resource temperature is higher than the average of 300oC, where drilling is shallower and less costly (Vo 1987) Geothermal resources are usually classified in various categories (dry vapor or hot water) depending on the mean annual ambient temperature which they could provide

Geothermal being a renewable resource does not emit any greenhouse gas emission and particularly the binary technology which is most suitable for geothermal power development in Vietnam is one of the most environmentally benign energy production technologies Further geothermal power provides baseload electricity at 90 % or above load factor and thus adds to the stability of the electricity grid

Renewable energy in Vietnam has been officially studied for several decades, with significant research on assessment of geothermal energy potential being funded by the state budget

The study from 1983 by the Geological Department produced a map of national hot water resources, with their respective geothermal potential, allowing the identification and prioritization of the regions which warrant further investigation The study from 1993 by RIGMR was also supported by international organizations (from New Zealand, Italy, and the USA) and identified 6 locations of geothermal potential (Bang, Tu Bong, Hoi Van, Danh Thanh, Mo Duc, Nghia Thang)

In 1995, ORMAT, along with PECC1, conducted pre-feasibility studies to select 6 locations for geothermal power plants in the Central region The total capacity was 112.7

MW, consisting of 3 power plants and with a capacity of 55.2 MW planned for the first stage However, due to several difficulties, the research was not continued

The study in 2004 by RIGMR concluded that the geothermal energy potential in Vietnam was 340 MW, but that the price of electricity generated was not competitive compared to other sources of energy

Because of all these factors, many countries despite having modest geothermal resources like Vietnam strive in harnessing this highly valuable and sustainable source of energy

In this paper, group authors going to show an overview observation about the characteristics of geothermal resources in Vietnam, especially in the Northern part of our country Furthermore, we also propose some solutions for potential geothermal power development and management

2 Methodology

2.1 Study potential geothermal sources (in the Northern part of Vietnam)

Active fault zones commonly have great effects on fluid transportation in geothermal reservoirs in the northern part of Vietnam During fault movement, all the pores and small fractures that meet with the fault plane become interconnected so that the inner

high permeability This is evidenced, for example by networks of mineral veins in deeply eroded fault zones in geothermal fields Inactive faults, however, may have low permeability and even act as flow barriers In geothermal reservoirs, the orientation of fault zones in relation to the current stress field and their internal structure needs to be known as accurately as possible One reason is that the activity of the fault zone depends on its angle

to the principal stress directions Another reason is that the outer part of a fault zone, the deformation zone, comprises numerous fractures of various sizes

Here we present field examples of faults, and associated joints in geothermal fields, and potential host rocks for geothermal reservoirs, respectively We studied several localities of different stratigraphy, lithology and tectonic settings: fault zones in outcrops from some basins

Geothermal activity in some basins has long been associated with transport and deposition of sediments, hot mineral springs appearance, making the zone become an important setting for investigating thermal processes Most studies have focused on fluid chemistry, the applicability of geothermal fluid (Cao 2004, Tran et al 2016) Epithermal deposits nonetheless form in zones of high permeability in relatively shallow parts of geothermal systems, along steeply dipping faults, fractures that were clear channels of strongly focused hydrothermal fluid flow (Nguyen et al 2005)

2.2 Analysis of the inquiry result on barriers

There are nineteen questionnaires given out to the respondents Among nineteen respondents, eleven ones are working on geology and the best ones are working in energy sectors So, the group can relatively divide the respondents into two groups: geology and non-geology In eleven respondents of the geology group, there are two engineers working for the companies of mining exploration, six researchers working at the research institutes and 3 researchers and teachers at the university Of the eleven geological respondents, there are three people hardly know about geothermal but eight people who have had time to do the research related to geothermal from 1 to 20 years Out of eight people with two people who have ever worked with geothermal development in Vietnam Among eight respondents of the non-geology group, there are four respondents working for the institute

of renewable energy and other four respondents working for the renewable power company All non-geology respondents are not experienced in geothermal research as well

as development

The respondents have expertise in geology or energy and have known more or less about geothermal or geothermal energy development so their answers are acceptable

The answers to the barriers are classified into categories, so the total percentage of individual barriers in a group is assumed to be a barrier percentage for that category The answers of 19 respondents were aggregated by means of the mean and considered as the result of the survey

3 Results

3.1 Current status of Geothermal energy potential in Vietnam

According to the result of surveying a total of 269 water sources covered all the regions of Vietnam carried out by RIGMR in 2005 (Table 1), there are 140 warm spring (52.1

%) and 84 hot spring (31.2%), 41 very hot (15.2 %) and 4 are extremely hot (1.5 %) The geothermal resources have been distributed following the geographic areas in Vietnam territory (Nguyen et al 2006)

The distribution of hot springs as follows: 39.8 % in the northern part, 39.5 % in the central part and 19.7 % in the southern part of Vietnam

Table 1: Hot springs classification according to the temperatures and potential areas (Nguyen et al

2006)

Temperature

grades

temp grades

%

plain

North- central

South-central

South

Warm

(30-40 °C)

Moderate

(41-60 °C)

Very hot

(61-100 °C)

So hot

(>100 °C)

Summated by

area

The geothermal utilization in Vietnam has been studied and applied in the year of '80s of the end of the last century for agricultural heating (tea, coconut-palm, manioc…) in

My Lam (Tuyen Quang province) and Hoi Van (Binh Dinh province) geothermal fields with the satisfactory result

However, they are the first pilots in the geothermal utilization and are carried out in

a difficult situation of economy and techniques in Vietnam, so there is still much limitation Besides, there are some research and applied projects of geothermal resources in order to maintain the crayfish throughout the winter

Up to now, almost all geothermal sources in Vietnam today are only used for direct utilization such as spa, bathing, hot water swimming pools, tourism such as: in My Lam, Quang Hanh, Binh Chau, Hoi Van geothermal resources etc and recently people in Quynh Phu and Hung Ha districts of Thai Binh province have used hot water for warming the fish breeding ponds and warming the chickens and pigs farm in the winter

According to the authors' prediction (topographic conditions, economic development potential, investment capacities), geothermal energy in Vietnam can develop

for Geothermal power plan (GPP) direction which will be presented in the next section (in the Northern part of Vietnam)

3.2 The most potential geothermal sources in the Northern part of Vietnam

Although only the reservoir temperature data is computed by the geothermometers through geochemical surveys for geothermal fields Parameters of geothermal reservoirs are estimated relatively based on geological maps, tectonic structures, and international references The thickness of each reservoir is estimated to be 2 m and the reservoir areas are 2.5 km2 Applying the computing methods for the potential of geothermal energy (Metcalfe 1986) Among 100 geothermal resources, there are 18 ones that can be directly applied to energy applications and can be also developed for electric generation (Figure 1 and Figure 2) The surface temperature and flow rate of geothermal water in the hot spring are used to calculate the natural thermal power that is waste heat if is not applied to human uses The results show that it is 8,960 tons of waste heat annually (Table 2) With the deep temperatures of reservoirs are varied from 136oC to 170oC, these geothermal resources can

be developed for electricity generation of the capacities from 4.2 MWe to 17.4 MWe The total electric generation capacity from 18 geothermal prospects is estimated to be about 170 MWe (Figure 2)

Figure 1 Location map of geothermal manifestation Numbers in the green cycle symbolizes the sources: 1- Pe Luong, 2-Na Hai, 3- Uva, 4-Pa Thom, 5-Pa Bat, 6-Pac Ma, 7-La Si, 8-Sin Chai, 9-Nam Cai, 10-Lang Sang, 11-Nam Pam, 12-Lung Po, 13-Bo Duot, 14-Quang Ngan, 15-Quang Nguyen,

16-My Lam, 17-Nam Ron, 18-Kim Da (Tran et al 2016) This map was modified from the Geological

map of Vietnam Scale 1/1.000.000 (Tran 1973)

Figure 2 Location map of potential geothermal sources related to the surface geothermal field (Numbers in the green cycle symbolize the sources refer to Figure 1) (Tran et al 2016) This map was modified from the Geological map of Vietnam Scale 1/1.000.000 (Tran 1973)

Table 2 Characteristics of potential geothermal sources in the Northern part of Vietnam (Tran 2014)

T(*)

Deep

T

Flow rate

Waste heat

Achievement temperature with

30 o C

- output T

Criterion energy with

30 o C - output

T

Geothermal energy potential for exploration

Electric generation capacity estimation

Sang

Pam

Ngan

Nguyen

Ron

Water 2019, 11, x; doi: FOR PEER REVIEW www.mdpi.com/journal/water

T(*): Temperature (Degrees Celsius-C)

Direct uses of geothermal energy have been applied in Vietnam where geothermal resources exist (Figure 2) The direct uses take the form of rudimentary traditional systems where communities living in the Northern part of Vietnam have used geothermal energy for various uses These various uses can help local inhabitants in tourism development like bathing, drying of crops, condensation of the steam to harvest potable water and boiling of eggs, to complex systems like district heating, greenhouse heating, and refrigeration In the Northern part of Vietnam, traditional systems are evidenced at Uva, My Lam, Thanh Thuy, Kim Quang Ngan where the local community has been tapping the steam for bathing, spas, ecotourism development

A large number of mountain areas in the Northern part of Vietnam include geothermal areas, usually with close links to volcanic activity Annual visitor numbers are considerable, but consist mainly of domestic travelers who visit the geothermal centers on their ‘hot spring pilgrimage’ Many Vietnamese ‘collect’ onsen and travel extensively to discover and experience as many hot springs in their country as possible

With the calculated temperature in the Northern part of Vietnam, the exploitation of regional energy for power generation purposes, we should use the Binary Cycle technology

to ensure the exploitation of energy from these sources The heat has a low source temperature, but at the same time protects the environment by not discharging hot water

3.2 The inquiry result on barriers

3.2.1 Geothermal power plan (GPP)

According to our survey results, both groups (geology and non-geology) agreed that policy and technique issues are the two biggest categories of the barrier For the non-geology group, the biggest category of the barrier is technical issues while for the geology group the biggest one is the policy issues In policy issues, the two groups agreed that national energy policy is the most important, then to the lack of incentives and the lack of investment in research and development Similarly, the technical category of barriers that stand up, the two groups agreed that the biggest barriers are lack of information or experience (general), then the data exploration technology, integration or interpretation (Table 3 and Figure 3)

While the geology group responded that the financial issues are major barriers accounted for 21%, the non-geology group responded that they are only accounted for 14% For the legal issues, the geology group’s response is the smallest barrier (13%) but the non-geology group’s response is not the smallest barrier (15%)

In general, both groups’ responses are not so different and can serve together by taking the average values Table 2 shows the order of the categories of barriers that stand for geothermal development are technical problems (25%), policy issues (24%), social issues (20), financial issues (18%) and finally to the legal issues (13%)

From the survey results may be temporarily assessed that the biggest category of barriers that stand with the development of geothermal energy in Vietnam is still technical issues in which the lack of information and experience are the most dominant factor (Table

3 and Figure 4) This is understandable because there has never been any geothermal resource exploration as well as any geothermal power generation in Vietnam so that can allow people to get complete information on the geothermal source and geothermal power plants The policy issues are the 2nd important factor hindering the development of geothermal power In more particular, national energy policy and economic incentives are the most important The 3rd biggest category of barriers that stand on social issues with special emphasis on the lack of specialists The fourth biggest category of barriers is financial and the category of legal barriers is evaluated as the smallest

In terms of barriers, here we see the barrier to exploration costs being the biggest (11.5%) The second biggest barriers are the lack of experts (9.8%) and the incentive policy (9.7%) to geothermal development

From a total of 28 barriers that stand investigated, there are 15 barriers that stand noteworthy because of a much higher percentage than any of the rest barriers that stand almost negligible Some barriers stand very low, to 0%, suggest that interviewees may not

be aware of it The change in the barrier rate from 0% to 11.5% indicates a fairly uniform assessment without focusing on certain barriers This further confirms that there is no geothermal power plant in Vietnam so it is impossible to have a clearer assessment of the certain barriers (Table 3 and Figure 4)

Table 3 Degrees of barriers hindering the geothermal power generation development in Vietnam