Geothermal Electricity Generation, Challenges, Opportunities and Recommendations

Abstract

Geothermal energy has a potential for several applications including geo-exchange, direct thermal application and power generation. Whereas the untapped capacity is over 100 GW globally, its growth realizes only 3-4% growth per year while the global share of electricity generation is less than 1%. Limitations of geothermal energy include scarcity of exploitable sites, remote locations often far from load centers and undesirable gaseous emissions. Project development faces challenges of poor funding, technology and long gestation periods of between 5 and 10 years for conventional power plants. Smooth implementation of geothermal project requires, social acceptance, through minimization of environmental effect, avoidance of adverse effects on the people and giving direct benefits to local communities. It is through both subsurface and power plant technologies that environmental challenges of geothermal power plants are addressed. Research and development into new, efficient and costeffective technologies will enhance safety and environmental integrity with respect to geothermal energy and electricity development. A geothermal power plant project generally goes through exploration or prefeasibility stage, drilling or feasibility stage and development stage which involves development of production wells, reinjection wells, steam gathering system and power plant construction and commissioning. The last phase is power plant operation and maintenance before the plant is finally retired upon end of the generation contract or license. These phases of the cycle before generation all combined take relatively long and there is need to improve. The use of Wellhead power plants currently provide a quick access to geothermal electricity ahead of full development of a conventional power plant hence enabling quicker access to geothermal electricity. Drilling which is a critical process in geothermal resource exploration and development is expensive, and therefore development of geophysical methods to resolve this problem is highly desirable as it could significantly reduce the cost of geothermal energy development hence advanced technology in drilling and upfront activities will reduce costs and risks in development. Better technology in upfront activities will significantly reduce the high risks and costs while power plant conversion technologies and better reservoir management and engineering will increase output, resource availability and efficiency of resource exploitation. Geothermal energy resources are significant and if the technical, financial, environmental, social and logistical challenges are addressed, it can be a major player in global energy and electricity market as renewable, safe and cheap resources. Research and development of technology and solutions to current challenges should be enhanced. The study concluded that technical barriers, high financial costs and long gestation periods prevent faster development of geothermal electricity.

Central versus wellhead power plants in geothermal grid electricity generation

“…Therefore, geothermal energy stored in the earth's crust alone has the capacity to supply the entire energy needs of the world at the current rate of consumption [19]. As a reliable energy source, geothermal power plants have a system reliability of more than 95% with a load factor greater than 95% for most power plants [5].…”

“…According to [22], about 1.8 GWe capacity growth was realized over the period 2005 to 2010, which translates to just 20% growth in 5 years, representing an average of about 350 MW more capacity per year or just 4% growth in geothermal electricity generation capacity globally. Between 2000 and 2005 a slower increment of about 200 MW/year was realized globally [5,22]. Ref.…”

“…Ref. [5] observed that whereas the global undeveloped geothermal electricity capacity was over 100 GW, its growth was low and on average it had been between 1 and 5% on a year-to-year basis for the last two decades [5] with globally shared total electricity generation being less than 1%.…”

“…The result of this delay places financial pressure on the project, often making it financially unattractive not just to financiers, but to investors as well because they usually have alternative projects to consider [4]. Geothermal energy for electricity generation has several benefits over other sources of energy [5]. These benefits include low cost energy, low emissions, a high power plant capacity factor and low land requirements, among others [4].…”

“…With significant potential, geothermal energy has a very important role in the energy transition [6]. There has been considerable interest in geothermal electricity due to increasing concerns over greenhouse gas emissions and global warming [5]. Global electricity generation processes cumulatively account for over 40% of combined global energy demand and remain a good indicator of a country's economic progress and performance [7].…”