Green Economy in a Blue World-Full Report

substantially lower than this figure and will depend on technical developments in wave- energy devices. Sims et al., (2007) estimate a global technical potential of 500 000 MW for wave energy, assuming that offshore wave- energy devices have an efficiency of 40 per cent and are only installed near coastlines. 1.5 Algae-based biofuels Algae-based biofuels can be regarded as a promising route to the production of future liquid transportation fuels. The typical production process benefits from the following advantages: a wide variety of input sources like combustion gas, seawater, brackish and waste water; suitability to many land and water types; availability of different production methods; likelihood of achieving good productivity levels when compared to most conventional (land- based) biomass feed stocks; and production of high grade oils that can be converted to fossil- fuel substitutes (IEA, 2011). Aside from the algal oil production and upgrading costs, which are currently high, the most significant limiting factors affecting algal biofuels are those imposed by the need for climatically favourable locations with suitable land, water and CO 2 resources. potential sustainable production volumes of algae biofuels worldwide are difficult to obtain at present. However algae biofuels are unlikely to displace a large fraction of current petroleum fossil-fuel usage (IEA, 2011). The economic viability of algae biofuels is still tentative. Currently there are little or no commercial-scale examples producing algae-based biofuels. The major challenges which have been identified are high initial capital input costs for algae cultivation and processing systems (higher than agriculture), and the low value of co-products to compensate higher production costs. 2 Challenges and opportunities 2.1 Marine-based renewable energy: driving forces, pressures, state, impact, response In order to understand the current context and challenges in the marine-based renewable energy sector, a DPSIR framework can be used to understand the links between driving forces, pressures, state, impact and responses. In short, it can be said that environmental and economic impacts associated with current fossil-fuel energy systems are driving changes that are encouraging development in renewable energy options. Within the general renewable energy context, marine-based renewable energy systems are increasingly being promoted due Meaningful estimates of the

in a Blue World

Forecast capacity of marine renewable energy types

8

Gigawatt

7

6

5

4

3

2

1

0

Types of marine renewable energy systems: 2019 2018 2017 2016 2015 2014 2013 2012 2020

Tidal barrage Tidal current Wave energy

Osmotic energy Ocean termal energy To be specified

Source: Frauenhofer Institute for Wind Energy and Energy Systems, 2011. Note: calculations are based on a selection of countries

to problems associated with predictability of land-based options and problems around social acceptance. In this way, the increase in demand for marine-based renewable energy can also be considered a driving force in itself for changes in the marine environment, potentially leading to conflicts with other users and the need for proactive seascape planning. Given these links, a double DPSIR framework is presented below. 2.2 The economic case for the marine- based renewable energy sector This section highlights the respective economic cases of selected marine-based renewable energies. Given the nascent stage of most options and the lack of commercial deployment experience, commercial cost and price data is not available, hence the exact economic potential for most marine-energy technologies is difficult to assess in absolute terms. As an alternative, total expected energy generation potential and price competitive capacity compared to fossil-fuel based energy is

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